UUO.ME[S,DOC]1 - www.SailDart.org

perm filename UUO.ME[S,DOC]1 blob sn#094745 filedate 1974-03-29 generic text, type C, neo UTF8

COMMENT ⊗ VALID 00263 PAGES
C REC PAGE DESCRIPTION
C00001 00001
C00036 00002
C00038 00003
C00040 00004 CONTENTS i
C00044 00005 CONTENTS ii
C00048 00006 CONTENTS iii
C00052 00007 1. Introduction Introduction 1
C00056 00008 1.1 UUOs (Un-Used Operation codes) Introduction 2
C00061 00009 1.2 Extended UUOs Introduction 3
C00064 00010 1.3 CALLs and CALLIs Introduction 4
C00068 00011 1.4 UUO Trapping and User-Defined UUOs Introduction 5
C00072 00012 1.6 Understanding this Manual Introduction 6
C00074 00013 2. General I/O General I/O 7
C00078 00014 2.1 User I/O Channels General I/O 8
C00083 00015 2.2 Data Modes General I/O 9
C00088 00016 2.2 Data Modes General I/O 10
C00092 00017 2.3 Dump Mode Command Lists General I/O 11
C00097 00018 2.4 Buffer Rings General I/O 12
C00101 00019 2.5 Buffers General I/O 13
C00106 00020 2.6 Device I/O Status Word General I/O 14
C00111 00021 2.6 Device I/O Status Word General I/O 15
C00116 00022 2.7 Files General I/O 16
C00120 00023 2.7 Files General I/O 17
C00125 00024 2.7 Files General I/O 18
C00129 00025 2.8 Initializing a Device General I/O 19
C00133 00026 2.8 Initializing a Device General I/O 20
C00137 00027 2.9 Setting Up Buffer Rings General I/O 21
C00141 00028 2.9 Setting Up Buffer Rings General I/O 22
C00144 00029 2.9 Setting Up Buffer Rings General I/O 23
C00147 00030 2.10 Opening Files General I/O 24
C00152 00031 2.10 Opening Files General I/O 25
C00156 00032 2.10 Opening Files General I/O 26
C00161 00033 2.10 Opening Files General I/O 27
C00166 00034 2.10 Opening Files General I/O 28
C00167 00035 2.10 Opening Files General I/O 29
C00170 00036 2.11 Transferring Data General I/O 30
C00174 00037 2.11 Transferring Data General I/O 31
C00178 00038 2.11 Transferring Data General I/O 32
C00181 00039 2.12 Terminating I/O General I/O 33
C00185 00040 2.12 Terminating I/O General I/O 34
C00190 00041 2.13 Random Access to Files General I/O 35
C00194 00042 2.13 Random Access to Files General I/O 36
C00197 00043 2.14 I/O Status Testing and Setting General I/O 37
C00201 00044 2.14 I/O Status Testing and Setting General I/O 38
C00206 00045 2.14 I/O Status Testing and Setting General I/O 39
C00209 00046 2.14 I/O Status Testing and Setting General I/O 40
C00213 00047 3. TTY I/O TTY I/O 41
C00217 00048 3.1 TTY Echoing and LF Insertion TTY I/O 42
C00222 00049 3.3 TTYUUO TTY I/O 43
C00224 00050 3.3 TTYUUO TTY I/O 44
C00227 00051 3.3 TTYUUO TTY I/O 45
C00231 00052 3.3 TTYUUO TTY I/O 46
C00235 00053 3.3 TTYUUO TTY I/O 47
C00240 00054 3.3 TTYUUO TTY I/O 48
C00244 00055 3.3 TTYUUO TTY I/O 49
C00247 00056 3.3 TTYUUO TTY I/O 50
C00251 00057 3.3 TTYUUO TTY I/O 51
C00254 00058 3.4 Miscellaneous TTY UUOs TTY I/O 52
C00258 00059 3.4 Miscellaneous TTY UUOs TTY I/O 53
C00261 00060 3.4 Miscellaneous TTY UUOs TTY I/O 54
C00265 00061 3.5 Pseudo-Teletypes TTY I/O 55
C00270 00062 3.5 Pseudo-Teletypes TTY I/O 56
C00274 00063 3.5 Pseudo-Teletypes TTY I/O 57
C00277 00064 3.5 Pseudo-Teletypes TTY I/O 58
C00280 00065 3.5 Pseudo-Teletypes TTY I/O 59
C00284 00066 3.5 Pseudo-Teletypes TTY I/O 60
C00287 00067 3.5 Pseudo-Teletypes TTY I/O 61
C00291 00068 3.5 Pseudo-Teletypes TTY I/O 62
C00294 00069 3.5 Pseudo-Teletypes TTY I/O 63
C00299 00070 3.5 Pseudo-Teletypes TTY I/O 64
C00303 00071 4. Display Output Display Output 65
C00307 00072 4.1 III Displays Display Output 66
C00311 00073 4.2 Data Disc Displays Display Output 67
C00315 00074 4.3 Page Printer Manipulation Display Output 68
C00318 00075 4.3 Page Printer Manipulation Display Output 69
C00321 00076 4.3 Page Printer Manipulation Display Output 70
C00324 00077 4.3 Page Printer Manipulation Display Output 71
C00328 00078 4.3 Page Printer Manipulation Display Output 72
C00332 00079 4.4 Running Display Programs Display Output 73
C00336 00080 4.4 Running Display Programs Display Output 74
C00339 00081 4.4 Running Display Programs Display Output 75
C00342 00082 4.4 Running Display Programs Display Output 76
C00345 00083 4.5 Extra Data Disc Channels Display Output 77
C00349 00084 4.5 Extra Data Disc Channels Display Output 78
C00353 00085 4.6 The Video Switch Display Output 79
C00355 00086 4.6 The Video Switch Display Output 80
C00360 00087 4.6 The Video Switch Display Output 81
C00363 00088 4.7 The Audio Switch Display Output 82
C00367 00089 4.7 The Audio Switch Display Output 83
C00370 00090 4.7 The Audio Switch Display Output 84
C00375 00091 4.7 The Audio Switch Display Output 85
C00379 00092 4.7 The Audio Switch Display Output 86
C00382 00093 5. Upper Segments Upper Segments 87
C00387 00094 5.1 Making and Killing Segments Upper Segments 88
C00392 00095 5.1 Making and Killing Segments Upper Segments 89
C00396 00096 5.1 Making and Killing Segments Upper Segments 90
C00400 00097 5.1 Making and Killing Segments Upper Segments 91
C00403 00098 5.2 Getting/Setting Segment Status Upper Segments 92
C00407 00099 5.2 Getting/Setting Segment Status Upper Segments 93
C00411 00100 5.2 Getting/Setting Segment Status Upper Segments 94
C00412 00101 6. Information Information 95
C00415 00102 6.1 Dates and Times Information 96
C00418 00103 6.1 Dates and Times Information 97
C00421 00104 6.2 Job Information Information 98
C00423 00105 6.2 Job Information Information 99
C00427 00106 6.2 Job Information Information 100
C00430 00107 6.3 Looking at the Monitor Information 101
C00434 00108 6.3 Looking at the Monitor Information 102
C00438 00109 6.3 Looking at the Monitor Information 103
C00442 00110 6.3 Looking at the Monitor Information 104
C00447 00111 6.3 Looking at the Monitor Information 105
C00450 00112 7. Mail System Mail System 106
C00453 00113 7.1 Sending Mail Mail System 107
C00457 00114 7.2 Receiving Mail Mail System 108
C00460 00115 7.3 Peeking at Mailboxes Mail System 109
C00463 00116 8. Spacewar Mode Spacewar Mode 110
C00468 00117 8. Spacewar Mode Spacewar Mode 111
C00473 00118 8. Spacewar Mode Spacewar Mode 112
C00477 00119 8.1 Spacewar UUOs Spacewar Mode 113
C00482 00120 8.1 Spacewar UUOs Spacewar Mode 114
C00483 00121 9. User Interrupts User Interrupts 115
C00488 00122 9. User Interrupts User Interrupts 116
C00492 00123 9. User Interrupts User Interrupts 117
C00497 00124 9. User Interrupts User Interrupts 118
C00501 00125 9. User Interrupts User Interrupts 119
C00506 00126 9. User Interrupts User Interrupts 120
C00510 00127 9.1 New Style Interrupts User Interrupts 121
C00514 00128 9.1 New Style Interrupts User Interrupts 122
C00519 00129 9.1 New Style Interrupts User Interrupts 123
C00522 00130 9.1 New Style Interrupts User Interrupts 124
C00526 00131 9.1 New Style Interrupts User Interrupts 125
C00529 00132 9.1 New Style Interrupts User Interrupts 126
C00532 00133 9.1 New Style Interrupts User Interrupts 127
C00535 00134 9.1 New Style Interrupts User Interrupts 128
C00538 00135 9.1 New Style Interrupts User Interrupts 129
C00541 00136 9.1 New Style Interrupts User Interrupts 130
C00544 00137 9.2 Old Style Interrupts User Interrupts 131
C00548 00138 9.2 Old Style Interrupts User Interrupts 132
C00550 00139 10. Fast Bands Fast Bands 133
C00555 00140 10.1 Getting and Releasing Fast Bands Fast Bands 134
C00559 00141 10.1 Getting and Releasing Fast Bands Fast Bands 135
C00562 00142 10.2 Reading and Writing Fast Bands Fast Bands 136
C00566 00143 10.3 Miscellaneous Fast Band UUOs Fast Bands 137
C00568 00144 11. Misc. UUOs Misc. UUOs 138
C00572 00145 11. Misc. UUOs Misc. UUOs 139
C00576 00146 11. Misc. UUOs Misc. UUOs 140
C00580 00147 11. Misc. UUOs Misc. UUOs 141
C00585 00148 11. Misc. UUOs Misc. UUOs 142
C00589 00149 11. Misc. UUOs Misc. UUOs 143
C00593 00150 11. Misc. UUOs Misc. UUOs 144
C00597 00151 11. Misc. UUOs Misc. UUOs 145
C00602 00152 11. Misc. UUOs Misc. UUOs 146
C00606 00153 11. Misc. UUOs Misc. UUOs 147
C00610 00154 11. Misc. UUOs Misc. UUOs 148
C00614 00155 11. Misc. UUOs Misc. UUOs 149
C00617 00156 12. Obsolete UUOs Obsolete UUOs 150
C00620 00157 12.1 Old UUOs Obsolete UUOs 151
C00623 00158 12.1 Old UUOs Obsolete UUOs 152
C00626 00159 12.1 Old UUOs Obsolete UUOs 153
C00629 00160 12.3 Useless UUOs Obsolete UUOs 154
C00630 00161 13. I/O Devices I/O Devices 155
C00634 00162 13.1 The Disk I/O Devices 156
C00638 00163 13.1 The Disk I/O Devices 157
C00643 00164 13.1 The Disk I/O Devices 158
C00645 00165 13.1 The Disk I/O Devices 159
C00648 00166 13.1 The Disk I/O Devices 160
C00652 00167 13.1 The Disk I/O Devices 161
C00654 00168 13.2 Terminals I/O Devices 162
C00655 00169 13.2 Terminals I/O Devices 163
C00660 00170 13.2 Terminals I/O Devices 164
C00661 00171 13.3 The Line Printer I/O Devices 165
C00665 00172 13.3 The Line Printer I/O Devices 166
C00667 00173 13.4 The XGP I/O Devices 167
C00671 00174 13.4 The XGP I/O Devices 168
C00676 00175 13.4 The XGP I/O Devices 169
C00681 00176 13.4 The XGP I/O Devices 170
C00685 00177 13.4 The XGP I/O Devices 171
C00690 00178 13.4 The XGP I/O Devices 172
C00693 00179 13.4 The XGP I/O Devices 173
C00696 00180 13.4 The XGP I/O Devices 174
C00699 00181 13.4 The XGP I/O Devices 175
C00702 00182 13.4 The XGP I/O Devices 176
C00706 00183 13.4 The XGP I/O Devices 177
C00709 00184 13.4 The XGP I/O Devices 178
C00711 00185 13.5 Dectapes I/O Devices 179
C00715 00186 13.5 Dectapes I/O Devices 180
C00719 00187 13.5 Dectapes I/O Devices 181
C00720 00188 13.6 Magnetic Tapes I/O Devices 182
C00724 00189 13.6 Magnetic Tapes I/O Devices 183
C00725 00190 13.6 Magnetic Tapes I/O Devices 184
C00728 00191 13.6 Magnetic Tapes I/O Devices 185
C00729 00192 13.7 Paper Tape Punch/Plotter I/O Devices 186
C00734 00193 13.7 Paper Tape Punch/Plotter I/O Devices 187
C00735 00194 13.8 Paper Tape Reader I/O Devices 188
C00738 00195 13.9 User Disk Pack I/O Devices 189
C00742 00196 13.9 User Disk Pack I/O Devices 190
C00745 00197 13.9 User Disk Pack I/O Devices 191
C00746 00198 13.10 AD/DA Converter I/O Devices 192
C00750 00199 13.10 AD/DA Converter I/O Devices 193
C00755 00200 13.10 AD/DA Converter I/O Devices 194
C00757 00201 13.11 TV Cameras I/O Devices 195
C00762 00202 13.11 TV Cameras I/O Devices 196
C00767 00203 13.11 TV Cameras I/O Devices 197
C00772 00204 13.11 TV Cameras I/O Devices 198
C00775 00205 13.12 The IMP I/O Devices 199
C00780 00206 13.12 The IMP I/O Devices 200
C00785 00207 13.12 The IMP I/O Devices 201
C00790 00208 13.12 The IMP I/O Devices 202
C00794 00209 13.12 The IMP I/O Devices 203
C00798 00210 13.12 The IMP I/O Devices 204
C00802 00211 13.12 The IMP I/O Devices 205
C00805 00212 13.12 The IMP I/O Devices 206
C00808 00213 13.12 The IMP I/O Devices 207
C00811 00214 13.12 The IMP I/O Devices 208
C00815 00215 13.12 The IMP I/O Devices 209
C00819 00216 14. Examples Examples 210
C00822 00217 14.1 Example of General I/O Examples 211
C00826 00218 14.1 Example of General I/O Examples 212
C00829 00219 14.2 Example of Display Programming Examples 213
C00833 00220 14.2 Example of Display Programming Examples 214
C00836 00221 14.2 Example of Display Programming Examples 215
C00839 00222 14.3 Example of Using Interrupts Examples 216
C00843 00223 Appendix 1 III Display Processor 217
C00847 00224 Appendix 1 III Display Processor 218
C00851 00225 Appendix 1 III Display Processor 219
C00855 00226 Appendix 1 III Display Processor 220
C00858 00227 Appendix 1 III Display Processor 221
C00861 00228 Appendix 1 III Display Processor 222
C00865 00229 Appendix 1 III Display Processor 223
C00867 00230 Appendix 2 Data Disc Display System 224
C00871 00231 Appendix 2 Data Disc Display System 225
C00875 00232 Appendix 2 Data Disc Display System 226
C00879 00233 Appendix 2 Data Disc Display System 227
C00884 00234 Appendix 2 Data Disc Display System 228
C00888 00235 Appendix 2 Data Disc Display System 229
C00893 00236 Appendix 2 Data Disc Display System 230
C00897 00237 Appendix 3 PDP-10 Information 231
C00901 00238 Appendix 3 PDP-10 Information 232
C00905 00239 Appendix 3 PDP-10 Information 233
C00909 00240 Appendix 3 PDP-10 Information 234
C00913 00241 Appendix 4 Job Data Area 235
C00917 00242 Appendix 4 Job Data Area 236
C00922 00243 Appendix 4 Job Data Area 237
C00927 00244 Appendix 4 Job Data Area 238
C00931 00245 Appendix 5 Monitor Pointers 239
C00935 00246 Appendix 5 Monitor Pointers 240
C00940 00247 Appendix 5 Monitor Pointers 241
C00945 00248 Appendix 5 Monitor Pointers 242
C00950 00249 Appendix 5 Monitor Pointers 243
C00955 00250 Appendix 5 Monitor Pointers 244
C00959 00251 Appendix 6 DDBs 245
C00963 00252 Appendix 6 DDBs 246
C00966 00253 Appendix 7 Stanford Character Set 247
C00970 00254 Appendix 8 UUOs by Number 248
C00976 00255 Appendix 8 UUOs by Number 249
C00980 00256 INDEX 250
C00985 00257 INDEX 251
C00990 00258 INDEX 252
C00996 00259 INDEX 253
C01001 00260 INDEX 254
C01006 00261 INDEX 255
C01012 00262 INDEX 256
C01018 00263 INDEX 257
C01021 ENDMK
C⊗;

STANFORD ARTIFICIAL INTELLIGENCE LABORATORY December 1973
OPERATING NOTE 55.3

U U O M A N U A L

Martin Frost

ABSTRACT

This document describes the UUOs (monitor calls) available to users
of the Stanford Artificial Intelligence Laboratory timesharing
system. Additional general information relevant to the use of the
UUOs is contained in the introductory section, and some useful tables
are included in the appendices. This manual supersedes SAILON 55.2
by Andy Moorer (MONITOR MANUAL, CHAPTER II).

This work was supported by the Advanced Research Projects Agency of
the Office of the Secretary of Defense under contract
DAHC15-73-C-0435.

ACKNOWLEDGEMENTS

The author wishes to thank the following people who contributed
significantly to this manual: Ralph Gorin for Section 13.4 on the
XGP, Ted Panofsky for Appendix 1 and Appendix 2 on the III and Data
Disc display systems (both appendices taken from Panofsky's FACILITY
MANUAL, SAILON 56), and Andy Moorer for Section 13.12 on the IMP.
Further thanks go to Brian Harvey for saving me the trouble of
writing the new MONITOR COMMAND MANUAL (SAILON 54.3) and for working
with me in getting our two manuals PUBed; to Dick Helliwell and Fred
Wright, whose contributions to the system helped make this manual
necessary; and finally to Larry Tesler for his PUB program and its
many new features without which this manual could not have been
printed so well on the XGP.
CONTENTS i

T A B L E O F C O N T E N T S

SECTION PAGE

1 INTRODUCTION 1

1.1 UUOs (Un-Used Operation codes) . . . . . . 1
1.2 Extended UUOs . . . . . . . . . . . . 2
1.3 CALLs and CALLIs . . . . . . . . . . . 3
1.4 UUO Trapping and User-Defined UUOs . . . . . 4
1.5 DEC vs. Stanford UUOs . . . . . . . . . 5
1.6 Understanding this Manual . . . . . . . . 5

2 GENERAL INPUT/OUTPUT 7

2.1 User I/O Channels . . . . . . . . . . . 8
2.2 Data Modes . . . . . . . . . . . . . 8
2.3 Dump Mode Command Lists . . . . . . . . .10
2.4 Buffer Rings . . . . . . . . . . . .11
2.5 Buffers . . . . . . . . . . . . .12
2.6 Device I/O Status Word . . . . . . . . .14
2.7 Files . . . . . . . . . . . . .16
2.8 Initializing a Device . . . . . . . . .18
2.9 Setting Up Buffer Rings . . . . . . . . .21
2.10 Opening Files . . . . . . . . . . . .23
2.11 Transferring Data . . . . . . . . . . .30
2.12 Terminating I/O . . . . . . . . . . .32
2.13 Random Access to Files . . . . . . . . .34
2.14 I/O Status Testing and Setting . . . . . .36

3 TTY INPUT/OUTPUT 41

3.1 TTY Echoing and LF Insertion . . . . . . .41
3.2 Codes Returned for Characters Typed . . . . .42
3.3 TTYUUO . . . . . . . . . . . . .43
3.4 Miscellaneous TTY UUOs . . . . . . . . .52
3.5 Pseudo-Teletypes . . . . . . . . . . .54

4 DISPLAY OUTPUT 65

4.1 III Displays . . . . . . . . . . . .65
4.2 Data Disc Displays . . . . . . . . . .66
4.3 Page Printer Manipulation . . . . . . . .67
CONTENTS ii

4.4 Running Display Programs . . . . . . . .72
4.5 Extra Data Disc Channels . . . . . . . .76
4.6 The Video Switch . . . . . . . . . . .78
4.7 The Audio Switch . . . . . . . . . . .81

5 UPPER SEGMENTS 87

5.1 Making and Killing Segments . . . . . . .88
5.2 Getting/Setting Segment Status . . . . . .91

6 GETTING/SETTING INFORMATION 95

6.1 Dates and Times . . . . . . . . . . .95
6.2 Job Information . . . . . . . . . . .97
6.3 Looking at the Monitor . . . . . . . . 100

7 INTER-JOB MAIL SYSTEM 106

7.1 Sending Mail . . . . . . . . . . . 106
7.2 Receiving Mail . . . . . . . . . . . 108
7.3 Peeking at Mailboxes . . . . . . . . . 108

8 SPACEWAR MODE 110

8.1 Spacewar UUOs . . . . . . . . . . . 112

9 USER INTERRUPTS 115

9.1 New Style Interrupts . . . . . . . . . 120
9.2 Old Style Interrupts . . . . . . . . . 130

10 LIBRASCOPE FAST BAND STORAGE 133

10.1 Getting and Releasing Fast Bands . . . . . 134
10.2 Reading and Writing Fast Bands . . . . . 135
10.3 Miscellaneous Fast Band UUOs . . . . . . 136

11 MISCELLANEOUS UUOS 138

12 OBSOLETE OR OTHERWISE USELESS UUOS 150
CONTENTS iii

12.1 Old UUOs . . . . . . . . . . . . 150
12.2 Privileged UUOs . . . . . . . . . . 153
12.3 Useless UUOs . . . . . . . . . . . 153

13 INDIVIDUAL DEVICE DESCRIPTIONS 155

13.1 The Disk . . . . . . . . . . . . 155
13.2 Terminals . . . . . . . . . . . . 162
13.3 The Line Printer . . . . . . . . . . 165
13.4 The XGP . . . . . . . . . . . . 167
13.5 Dectapes . . . . . . . . . . . . 179
13.6 Magnetic Tapes . . . . . . . . . . . 182
13.7 Paper Tape Punch/Plotter . . . . . . . 186
13.8 Paper Tape Reader . . . . . . . . . . 188
13.9 User Disk Pack . . . . . . . . . . . 189
13.10 AD/DA Converter . . . . . . . . . . 192
13.11 TV Cameras . . . . . . . . . . . . 195
13.12 The IMP . . . . . . . . . . . . 199

14 EXAMPLES 210

14.1 Example of General I/O . . . . . . . . 210
14.2 Example of Display Programming . . . . . 212
14.3 Example of Using Interrupts . . . . . . 215

A P P E N D I C E S

1 III DISPLAY PROCESSOR 217

2 DATA DISC DISPLAY SYSTEM 224

3 GENERAL INFORMATION ABOUT THE PDP-10 231

4 JOB DATA AREA 235

5 LOCATIONS OF USEFUL POINTERS IN THE MONITOR 239

6 DEVICE DATA BLOCKS (DDBS) 245

7 STANFORD CHARACTER SET 247

8 UUOS BY NUMBER 248
1. Introduction Introduction 1

SECTION 1

INTRODUCTION

This document describes the UUOs (monitor calls) available to users
of the Stanford Artificial Intelligence Laboratory timesharing
system. Additional general information relevant to the use of UUOs
is contained in this introductory section, and some useful tables are
included in the appendices. This manual supersedes SAILON 55.2 by
Andy Moorer (MONITOR MANUAL, CHAPTER II).

The reader is assumed to know the PDP-10 instruction set and format,
data types and assembly languages. However, the aspects of these
subjects that are relevant to this manual are explained in Appendix
3. The user who is new to the PDP-10 should read that appendix
before going any further. The experienced user may skip to Section
1.6, UNDERSTANDING THIS MANUAL.

1.1 UUOs (Un-Used Operation codes)

UUOs are monitor calls which make use of instruction codes that would
otherwise be unused or illegal. The opcodes from 000 to 077 are not
used by any machine instruction, and opcodes from 700 to 777 are
input/output machine instructions, which are normally illegal in user
programs. All these opcodes trap to the monitor, which can then take
whatever action it deems appropriate. Taking advantage of this
situation, the system designates some of these opcodes to be monitor
calls for certain common functions such as I/O. Thus whenever a UUO
is encountered in the instruction stream, the monitor is called to
execute the function corresponding to the particular UUO. When the
function has been executed, control returns to the user program.
Some UUOs may take skip returns; that is, control does not always
return at the instruction immediately following the UUO, but
sometimes at one of the next instructions after that one. The
individual writeups explain when a UUO skips; unless otherwise
described, a UUO's return is always at the instruction immediately
following the UUO.

Some UUOs take arguments or return values in memory cells. In such
cases the cells can be accumulators (ACs), but a block of such cells
must not extend beyond the last accumulator (octal 17) because words
20 through 37 in a user's core image are used by the system for
special temporary storage of sets of ACs. (Words 40 through 137 are
1.1 UUOs (Un-Used Operation codes) Introduction 2

used by the system to store information about the job. This part of
a core image is referred to as the Job Data Area; the data stored
here is described in Appendix 4.)

Note also that some UUOs have unused argument fields. Such a field
should be made zero so that if at some later time it becomes used for
a new feature, an old program using that UUO will still work.

Some of the opcodes not defined by the system are available to the
user for defining his own special purpose UUOs. The method for
defining these UUOs is explained in Section 1.4. The categories of
opcodes that are used for UUOs are:

000 always illegal,
001:037 user-definable UUOs,
040:077 system-defined regular UUOs,
700:777 system-defined IOT UUOs.

The IOT UUOS are available only when the program is NOT in IOT-USER
mode; in IOT-USER mode these opcodes are machine I/O instructions
instead. A user program will not be in IOT-USER mode unless it has
done something special to get into that mode. For a complete
explanation of IOT-USER mode, see Appendix 3.

Finally, a special feature allows the user to have normal
system-defined UUOs trap to a given location in the user program
instead of being executed by the system. For details of this
feature, see the UUOSIM UUO on page 145.

1.2 Extended UUOs

In order to define more UUOs than there are opcodes available, two
primary methods are employed that allow a single opcode to represent
many different UUO functions. The first of these methods is to use
the value of the accumulator (AC) field in the instruction to specify
one of 20 (octal) possible UUOs for a given opcode. Thus, for
example, the OUTSTR UUO (which types out an ASCIZ string on the
terminal) is invoked by specifying the opcode 051 and the AC field 3.
There are currently six opcodes that use the value of the AC field in
this manner. Each of these opcodes has a generic mnemonic which,
together with a specific value for the AC field, can be used to
indicate a specific UUO. In addition, each combination of generic
mnemonic and specific AC field has a specific mnemonic which also can
be used to indicate the UUO. Opcode 051 has the generic mnemonic
TTYUUO, and TTYUUO with an AC field of 3 has the specific mnemonic
OUTSTR. Thus the following three lines of code are equivalent. (ADR
1.2 Extended UUOs Introduction 3

is an argument of this UUO; it specifies the address of the ASCIZ
string to be typed out.)

OUTSTR ADR
TTYUUO 3,ADR
051140,,ADR

Note, however, that not all of the mnemonics are known by all of the
assemblers or all of the debuggers. FAIL, however, gets its UUO
mnemonic definitions directly from the system and thus is always up
to date, even just after a new UUO has been added.

1.3 CALLs and CALLIs

The second method of defining many UUOs with the same opcode has two
versions. In one of these, the address field of the UUO points to a
word which contains the sixbit name of the UUO function desired. In
the other version, the address field of the UUO is itself the number
of the function desired. The opcode in the first case is 040 and its
mnemonic is CALL; the opcode in the second case is 047 and its
mnemonic is CALLI (for CALL Immediate).

CALL [OP=040]
--------------------------------------------------
CALL AC,[SIXBIT /<name>/]

CALLI [OP=047]
--------------------------------------------------
CALLI AC,<number>

Exactly the same UUO functions are available through these two
methods. Thus, the following two lines of code are functionally
equivalent; each will cause execution of the EXIT UUO.

CALLI 12
CALL [SIXBIT /EXIT/]

Since there are these two versions of calling the same UUOs, the
following fact should be noted. When you use a CALL instead of a
CALLI, not only do you need an extra word in which to store the name
of the CALL function, but also (and more importantly) you force the
system to look up the function name in a table in order to find out
1.3 CALLs and CALLIs Introduction 4

the function number. This means that using CALLs instead of CALLIs
creates a substantial amount of extra work that could be completely
avoided. In addition, it is easier to use CALLIs instead of CALLs
because, in FAIL and MACRO, if you use the name of a CALL as an
opcode, the appropriate CALLI will be generated. (In MACRO, only the
DEC CALLIs are predefined.) For example, the following two lines
will produce the same machine code.

CALLI 12
EXIT

Thus the CALL UUO is essentially obsolete; it is mentioned here
mainly for completeness sake. Please use CALLIs!

1.4 UUO Trapping and User-Defined UUOs

The method employed by the PDP-10 to trap to the monitor when an
unused opcode is encountered is the following:

1. The effective address calculation for the instruction is
carried out as usual with the address field, index field and
indirect bit in the instruction and in any words referenced
indirectly by the instruction.
2. Bits 0 to 12 (opcode and AC field) of the instruction are
deposited in bits 0 to 12 of user or monitor location 40
(depending on whether the opcode represents a user or a
monitor UUO). The calculated effective address from 1 above
is deposited into bits 18 to 35 (address field) of the same
location 40. Bits 13 to 17 (index field and indirect bit)
of this location are cleared.
3. The instruction at location 41 (user or monitor as above) is
then executed (as if from an XCT instruction). This
location usually contains a JSR instruction to jump to a
subroutine to interpret the UUO. The JSR saves the program
counter (which points to the instruction immediately
following the UUO) for returning to the program containing
the UUO.

Thus, for a user to define his own UUOs (selected from opcodes 001 to
037), he need only deposit a JSR or similar instruction in user
location 41 to jump to the subroutine that will interpret his user
UUOs. The instruction in location 41 should be one that saves the
program counter for returning. For instance it could be a PUSHJ if
you have a stack.

Note: Because the effective address calculation has already been
1.4 UUO Trapping and User-Defined UUOs Introduction 5

completed by the time a UUO's function is executed, what the monitor
(or a user's UUO code) sees in the address field of a UUO is this
effective address. In the UUO writeups in this manual, the two
expressions THE EFFECTIVE ADDRESS OF THE UUO and THE ADDRESS FIELD OF
THE UUO mean the same thing, namely, this final value of the
effective address calculation.

(In the Stanford system, UUOs trapping into the monitor actually go
to absolute 140 and 141 rather than 40 and 41 although user UUOs do
trap to user 40 and 41.)

1.5 DEC vs. Stanford UUOs

UUOs with opcodes 040 through 077 and CALLIs with numbers 0 through
44 are essentially standard DEC UUOs modified for use at Stanford.
(Some have been modified completely out of existence.) The
exceptions are the TTYUUOs (opcode 051) with AC fields 14 through 17
and the SPCWAR UUO (opcode 043), which are special Stanford UUOs.
All of the IOT UUOs (opcodes over 700) and all CALLIs with numbers
from 400000 up are also special Stanford UUOs.

1.6 Understanding this Manual

In each of the sections that follow, a collection of related UUOs is
explained along with the system concepts involved. Preceding the
writeup for each UUO are 1) a line containing the UUO's mnemonics and
numerical codes and 2) a sample usage (calling procedure) to which
the writeup will often refer. For numerical codes, the abbreviation
OP stands for the operation code field, AC for the accumulator field
and ADR for the effective address of the UUO. For CALL/CALLI UUOs,
the numerics will be those of the CALLI.

The phrases AC LEFT and AC RIGHT mean, respectively, THE LEFT HALF OF
AC and THE RIGHT HALF OF AC.

Wherever there is a data block of length N used or set up by a UUO,
the words of the block will be referred to as WORD 0 through WORD N-1
or sometimes (usually with short blocks) as THE FIRST WORD through
THE NTH WORD. Please note the difference between these two
terminologies.

A range of bits or words will often be referenced by an expression of
the form "X:Y", where X and Y are numbers. This represents all
1.6 Understanding this Manual Introduction 6

values from X through Y. For example, "bits 18:26" means bits 18
through 26.

All numbers will be in OCTAL except for the following, which will be
in DECIMAL: bit numbers (e.g., "bit 35"), byte sizes (e.g., "12-bit
bytes"), times (e.g., "30 seconds"), and numbers preceded by an
equals sign (e.g., "=15").

References to particular bits or groups of bits will usually be made
both by the bit numbers and by the octal value resulting from 1's in
the specified bit positions. For example:

...if bit 0 (400000,,0 bit) is on...
...and bits 18:26 (0,,777000 bits)...

The octal value will be in half-word format, as shown above.
2. General I/O General I/O 7

SECTION 2

GENERAL INPUT/OUTPUT

The purpose of input/output (I/O) is to transfer data between the
computer's memory and an external device such as a tape, a disk, a
printer, etc. The UUOs are set up to allow I/O with a fair amount of
flexibility and device independence. I/O here is done on a very low
level and involves three basic phases: initialization of the device,
transfer of the data, and releasing of the device. Another phase,
file selection, is necessary for the disk and other directory
devices.

There are other simpler forms of I/O for certain devices (including
terminals); I/O for those devices is explained in later sections.

The basic phases of I/O can be seen in the corresponding UUOs, so I
will give an example sequence of the UUOs used in I/O. Since much of
the I/O done by programs uses the disk, I will include the file
selection phase in the example below. Note that this example is not
a complete program; it contains only some excerpts involving the use
of UUOs. This is intended to introduce you to various I/O concepts
which will be explained in great detail in the remainder of this
section.

INIT 1,10 ;This initializes the disk (DSK) on channel 1 in
SIXBIT /DSK/ ; mode 10 and specifies an output buffer header at
OBUF,,0 ; location OBUF. Upon an error in the execution
HALT . ; of this UUO, the program will HALT.

ENTER 1,FILE ;This opens the file specified at location FILE for
HALT . ; output on channel 1; this will HALT on any error.

OUTPUT 1, ;This is used to write out data on channel 1.

CLOSE 1, ;This closes the file open on channel 1.

RELEAS 1, ;This releases the device on channel 1.

In general I/O, the methods for doing output are very similar to
those for doing input. Consequently, the following discussion will
describe the basics of input; minor differences for doing output will
usually be mentioned in parenthetical remarks. Any significant
differences will be called to your attention.
2.1 User I/O Channels General I/O 8

2.1 User I/O Channels

A program is allowed to use up to 20 I/O devices at the same time.
In order to keep straight which device an I/O UUO is meant for, each
device in use is assigned a CHANNEL NUMBER. The channel number,
which can be any number between 0 and 17 inclusive, is specified by
the user when he initializes the device. Subsequent operations
involving that device refer only to the channel number and not to the
name of the device. The channel number is chosen by the user and has
significance only to the program in which it is assigned.
Furthermore, when a device is released, the channel number is
disassociated from it; so if the device is to be used again, it must
be initialized again with a new (possibly the same) channel number.

A single I/O channel may not be used for both input and output at the
same time, except on the disk in the special Read-Alter (RA) mode,
which is explained on page 27.

2.2 Data Modes

When you are doing I/O, you must select the data mode to be used.
The mode indicates how the data is to be transferred: primarily,
whether the data transfers are to be buffered and, if so, whether the
data is made up of characters or of full words.

In buffered mode, the system transfers data between the device and
some buffers in your core area. A transfer of this type is initiated
for input by the INPUT UUO and for output by the OUTPUT UUO. To get
data from a buffer on input or to put data into a buffer for output,
you simply do ILDBs (input) or IDPBs (output) with a byte pointer
that is set up by the system. The data is thus handled a byte at a
time, with the bytes being either characters (7 bits each) or full
words (36 bits each); the mode determines the byte size. When a
buffer is used up, you give an INPUT UUO to get another buffer of
data (or an OUTPUT UUO to write out a buffer of data). The buffers
you use are set up by the system in the form of buffer rings. Buffer
rings will be described in detail in Section 2.4, but now back to
data modes.

The alternative to buffered mode is dump mode. To read (write) in
dump mode, you tell the system where in your core image you want the
data to go (come from) and how many words are to be transferred.
This is done with dump mode command lists, which will be explained in
Section 2.3.
2.2 Data Modes General I/O 9

The basic data modes are listed in the following table and described
below. (There are many special modes for specific devices; these
modes are described in Section 13, which deals with device-dependent
features.)

MODE NAME TYPE OF TRANSFERS

0 ASCII Buffered characters (7-bit byte pointer)
1 ASCII LINE Buffered characters (7-bit byte pointer)
10 IMAGE Buffered words (36-bit byte pointer)
13 IMAGE BINARY Buffered words (36-bit byte pointer)
14 BINARY Buffered words (36-bit byte pointer)
16 DUMP RECORD Unbuffered
17 DUMP Unbuffered

ASCII mode (mode 0) is used for inputting (outputting) text. You get
(put) one ascii character at a time from (into) your buffer by using
the byte pointer. (Note: For TTY input in ASCII mode, an INPUT UUO
will not return until your TTY buffer is full (holding =95
characters) or ↑Z (control-meta-linefeed on the displays) is typed.
However, TTY I/O is usually done with the special UUOs described in
Section 3.)

ASCII LINE mode (1) is the same as ASCII mode except for TTY input.
There it means that an INPUT UUO will return when an activation
character is typed or when the buffer is full, whichever comes first.
(Normally the activation characters are carriage return, linefeed,
altmode and control characters.)

IMAGE mode (10) is similar to ASCII mode except that the bytes are 36
bits instead of 7. When you do an ILDB (IDPB) you get (put) a whole
word from (into) the buffer. You can read text files in this mode,
in which case you will get 5 characters at a time.

IMAGE BINARY (13) and BINARY (14) modes are the same as IMAGE mode
except for the paper tape reader and punch and the XGP. See Section
13.4 for the use of mode 13 with the XGP, and see Section 13.7 and
Section 13.8 for the meanings of these modes with paper tape I/O.

DUMP mode (17) is used to do I/O without buffering. With each INPUT
or OUTPUT UUO, you must give the address of a dump mode command list,
which specifies how many words are to be transferred and where in
your core image they are to come from or go. The INPUT or OUTPUT UUO
does not return until the transfer is complete. Dump mode command
lists are explained below.

DUMP RECORD mode (16) is the same as DUMP mode for most devices.
However, with output on magnetic tapes in DUMP RECORD mode, the data
from each dump mode command is written on the tape in 200 word
2.2 Data Modes General I/O 10

records, whereas in DUMP mode the data from each command is written
in one large record.

2.3 Dump Mode Command Lists

The effective address of an INPUT or OUTPUT UUO in dump mode (16 or
17) must be the address of a dump mode command list. This list
consists of up to 100 dump mode commands, each of which takes one
word. The end of the list is indicated by a zero word after the last
command.

In the left half of a dump mode command word is the negative of the
number of words to be transferred, and in the right half is the
address of the word BEFORE the first word in your core image to which
(from which) the data is to go (come).

(This is the standard dump mode command format. Some devices like
the TV cameras and the AD converter take non-standard dump mode
commands. See the individual device descriptions in Section 13.)

In the assembly languages, there is a pseudo-op called IOWD that
generates dump mode commands. The line
IOWD N,LOC
generates a word with -N in the left half and LOC-1 in the right
half. As a dump mode command, this will cause N words to be
transferred to (from) the block consisting of locations LOC through
LOC+N-1.

Each dump mode command in a list causes a separate I/O transfer to
take place. In particular, with record devices (like the disk,
dectapes and magnetic tapes) each command is executed from the
beginning of a record. For example the command list

IOWD 100,A
IOWD 100,B
0

will read 100 words from one record and then 100 words from the next
record, IGNORING ALL BUT THE FIRST 100 WORDS OF EACH RECORD.

Consecutive commands in a list are usually fetched from consecutive
words. However, if the LEFT half of a dump mode command word is
zero, then that word is taken NOT as a command, but as a POINTER to
the next command word, which is then fetched from the location
specified by the RIGHT half of that word. (Of course, if the right
half is zero also, then that word marks the end of the command list.)
2.3 Dump Mode Command Lists General I/O 11

For example, the two command lists given below (beginning at LIST1
and LIST2, respectively) are equivalent.

The only difference is that in the second example, the commands are
in two different places instead of being directly in line. Either of
these lists would cause 200 words to be transferred to (from) LOC1
and then 200 words to (from) LOC2.

2.4 Buffer Rings

When you are doing input (output) in one of the buffered modes, a
ring of buffers is set up by the system for storage of data in your
core image. This allows you to empty (fill) one buffer while the
device is filling (emptying) another buffer independently.

A buffer ring consists of some number of buffers with each one
containing a pointer to the next. The last buffer contains a pointer
to the first; hence it is a ring. The user can specify the number of
buffers in a ring with the INBUF and OUTBUF UUOs (see Section 2.9),
or he can accept the system default number of buffers, which is two.
The current buffer in a ring is referenced through a three word block
called the BUFFER HEADER. When you initialize a device in buffered
mode, you give the address of a three word block where the buffer
header is. The system will initialize the header when it sets up the
buffer ring.

The buffer header contains 1) a bit indicating whether the buffer has
ever been used, 2) a pointer to the buffer the user is currently
emptying (filling), 3) the byte pointer that is used for loading
(storing) data from (into) the current buffer, and 4) a count of the
number of bytes left in the current buffer. Normally only the byte
pointer and the byte count are needed by the user. The byte pointer
is in the second word of the header and the byte count in the third.
The first word contains the use indicator in the sign bit (400000,,0
bit) (which is set to 1 when the buffers are created and cleared to
zero when the first INPUT or OUTPUT UUO is given) and the buffer
pointer in the right half. For input, the byte count is the number
of bytes of data left in the buffer; for output it is the number of
bytes not yet filled with data by the user. The byte pointer is set
2.4 Buffer Rings General I/O 12

up so that you can get (put) the next byte by doing an ILDB (IDPB).
When you initialize a device in buffered mode, the system clears the
buffer header and then sets up the size field of the byte pointer.
If you so desire, you may then change the byte size to any size you
want, and the system will do the right things. (The system actually
uses the byte size in the byte pointer to calculate the byte count.)
Finally, whenever you do an INPUT or OUTPUT UUO, the system updates
the entire buffer header before returning control to you.

2.5 Buffers

The first three words of each buffer are used by the system and
contain no data. The first word contains the device I/O status word
(explained in Section 2.6) for the device at the time the buffer
was transferred. The left half of the second word has the size of
the buffer not counting the first two words, that is, the number of
data words in the buffer plus one. The right half of the second word
holds the address of the next buffer in the ring (which may be the
same buffer). All pointers to buffers, both in the buffer header and
from one buffer to the next, point not to the first word of the
buffer but to the second word, where the pointer to the next buffer
is. The sign bit (400000,,0 bit) of the second word in a buffer is
set to 1 by the system when the buffer is full of data and cleared to
0 when it is empty.

The right half of the third word holds a count of the number of words
of data actually contained in the buffer. The left half of this word
is reserved for bookkeeping use by the system. On output the word
count is computed from the byte pointer in the buffer header unless
the IOWC bit in the device status word (see Section 2.6) is on, in
which case the value in the third word of the buffer is taken as the
count. That means you must specifically place the word count there
yourself. Many devices (including the disk) will not take a word
count larger than their standard buffer size. There are at least two
devices that will accept buffers of any size: terminals and magnetic
tapes. For other devices, consult the individual device writeup in
Section 13.

The illustration on the next page shows the structure of a buffer
ring with two buffers.
2.5 Buffers General I/O 13

DIAGRAM OF A 2-BUFFER RING

BUFFER HEADER

-------------------------------------- \
|s| | buffer pointer |→→→→→→→→→→↓
-------------------------------------- / ↓
| byte pointer | ↓
-------------------------------------- ↓
| byte count | ↓
-------------------------------------- ↓
↓
↓
↓←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←
↓ FIRST BUFFER ↑
↓ ↑
↓ -------------------------------------- ↑
↓ | I/O status bits | ↑
↓ \ -------------------------------------- \ ↑
→→→→→→→→|s| data size + 1 | buffer pointer |→→→→→→→→→→↓ ↑
/ -------------------------------------- / ↓ ↑
| bookkeeping | data word count | ↓ ↑
-------------------------------------- ↓ ↑
| | ↓ ↑
| | ↓ ↑
| data | ↓ ↑
| | ↓ ↑
| | ↓ ↑
-------------------------------------- ↓ ↑
↓ ↑
↓ ↑
↓←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←←← ↑
↓ SECOND BUFFER ↑
↓ ↑
↓ -------------------------------------- ↑
↓ | I/O status bits | ↑
↓ \ -------------------------------------- \ ↑
→→→→→→→→|s| data size + 1 | buffer pointer |→→→→→→→→→→→→→→→→→→↑
/ -------------------------------------- /
| bookkeeping | data word count |
--------------------------------------
| |
| |
| data |
| |
| |
--------------------------------------
2.6 Device I/O Status Word General I/O 14

2.6 Device I/O Status Word

For each device on the system there is a word called the device I/O
status word. The left half of this word is used internally by the
system and the right half is used to communicate with the user. The
right half word is set up when the user initializes the device.
Thereafter, certain bits may be set by the system to tell the user of
conditions that have arisen (such as end of file). These bits can be
tested or changed by the user with the STATZ, STATO, GETSTS and
SETSTS UUOs (see Section 2.14). The following table gives the
meanings of the bits in the right half of the device status word.

BITS OCTAL NAME MEANINGS OF 1'S IN DEVICE
STATUS WORD

18 0,,400000 IOIMPM Improper mode. This can mean
many things. If you attempt
to write on a write-locked
dectape or UDP, you get this
error bit. If you initialize
a device in a mode that is not
legal for that device, you
will get either this error bit
or a system error message.

19 0,,200000 IODERR Device detected error.

20 0,,100000 IODTER Device detected error. This
bit and the IODERR bit
generally mean that the device
has detected an undesirable,
if not catastrophic,
condition.

21 0,,40000 IOBKTL Dectape block number out of
bounds. This bit comes on if
you reference a non-existent
block on a dectape.

22 0,,20000 IODEND End of file. This bit comes
on only with input; it means
there is no more data to be
read in because you have
reached the end of the file.
On teletypes and
pseudo-teletypes, end of file
is indicated by typing
control-Z (↑Z); on Data Disc
2.6 Device I/O Status Word General I/O 15

and III displays, end of file
is indicated by typing
control-meta-linefeed.

23 0,,10000 IOACT Device is active.

24:29 0,,7700 Reserved for device-dependent
features.

30 0,,40 IOCON Synchronize buffered I/O. An
attempt is made to make
buffered I/O synchronous when
this bit is on. That is,
exactly one buffer is
transmitted for every INPUT
UUO and at most one buffer for
each OUTPUT UUO. The best way
to insure synchronous I/O,
however, is to have exactly
one buffer in your ring, or
better yet, to use dump mode.

31 0,,20 IOWC Inhibit system computation of
output word count. The system
is inhibited from computing
the word count that goes in
the third word of each buffer.
Normally, when you do an
OUTPUT UUO in buffered mode,
the system uses the byte
pointer in the buffer header
to compute the number of words
of data in the buffer. This
computed word count is then
deposited in the third word of
the buffer. If the IOWC bit
is on, the word count
computation is inhibited and
whatever is in the third word
of the buffer is taken as
gospel for the word count.

32:35 0,,17 Data mode.
2.7 Files General I/O 16

2.7 Files

Data on certain devices is stored in the form of files. To access
data on one of these devices, you must specify the filename in
addition to the device name. Devices that are file structured are
called directory devices; the disk and dectapes are such devices.

Every file has a name of one to six characters and an optional
extension of one to three characters. On the disk each file is
associated with some project-programmer name (PPN). A
project-programmer name consists of a project code and a programmer
code, each of which is one to three characters. All of the files for
a particular project-programmer name are referred to collectively as
that PPN's disk area.

File names, file name extensions and project-programmer names are
stored in SIXBIT representation. File names are left-justified in
one whole word; file name extensions are left-justified in the left
half of a word. If a filename has no extension, the extension half
word is zero. A zero file name is not permitted. Project-programmer
names are stored in one word with the project code in the left half
and the programmer code in the right half, each half being
right-justified. For an example of all this, the file RAD.Y[A,BC]
would be represented by the following octal values and corresponding
assembly language lines of code (the date word is included to make
this four-word block into a sample block for the LOOKUP UUO):

OCTAL ASSEMBLY LANGUAGE

file name: 624144000000 SIXBIT /RAD/
extension: 710000000000 SIXBIT /Y/
date word: 000000000000 0
PPN: 000041004243 SIXBIT / A BC/

where 62 is the octal value for "R" in sixbit, 41 is the octal value
for "A" in sixbit, etc.

Disk File Protection System

Each file on the disk has a nine-bit protection key that indicates
who may do what to the file. A one in the first bit (400 bit)
position means that the file dumping program DART (that provides file
backup on magnetic tape) should never dump this file. A one in the
second bit (200 bit) means that COPY should not delete this file
without getting special confirmation; this prevents accidental
2.7 Files General I/O 17

deletion of a file with the monitor DELETE command. The remaining
seven bits (177 bits) are broken into three groups: the third bit
(100 bit) tells what the owner of the file may do to the file, the
middle three bits (070 bits) tell what a PPN consisting of the
owner's programmer code and a different project code may do with the
file, and the last three bits (007 bits) tell what anyone else may
do. Corresponding bits in these last two groups mean the same thing
but for the two different classes of users. The sole bit in the
first group means the same as the third bit in each of the other
groups but applies to the owner of the file.

In each group, a one in the first bit position (the 4 bit) means that
the users corresponding to that group are not permitted to change the
file's protection key. This is called PROTECTION PROTECTION. A user
is always permitted to change the protection keys of his own files.
A one in the second bit position (the 2 bit) means that the
corresponding users may not read the file. This is called READ
PROTECTION, and, again, a user may always read his own files. A one
in the third bit position (the 1 bit) means that the corresponding
users may not write, alter or delete the file. This is called WRITE
PROTECTION.

Here is a summary of the nine protection bits.

BITS OCTAL MEANING

0 400 Dump never (DART only).
1 200 Delete protect (COPY only).
2 100 Write protection for the file's owner.
3:5 070 Protection, read, and write protection for
PPNs consisting of the owner's programmer
code and some other project code.
6:8 007 Protection, read, and write protection for
others.

Disk Project-Programmer Names

When you reference a file on the disk, you must specify the
project-programmer name of the file's owner. If the file is your
own, this can be done by indicating a PPN word of zero. Sometimes,
however, you would like a program to act as if it were logged in
under a different PPN. This can be accomplished with respect to file
references through the use of Disk PPNs and the DSKPPN UUO. Each job
has associated with it a Disk Project-Programmer Name (the Disk PPN)
that is used whenever the PPN word for a disk file specification
contains zero. Your Disk PPN is set to your real PPN when you log in
2.7 Files General I/O 18

and can be changed with the monitor ALIAS command; it can also be
changed or retrieved with the DSKPPN UUO. Thus if you specify a file
with a zero PPN, the project-programmer name of your Disk PPN will be
assumed for the file. This method does not, however, allow you
violate any protection keys for the files you reference. These
protection keys are applied to your real (logged in) PPN to see if
you are permitted the kind of access you are requesting for the file.

DSKPPN [OP=047, ADR=400071] CALLI 400071
--------------------------------------------------
MOVE AC,[<code>]
DSKPPN AC,

Code Meaning

0 Return own Disk PPN in AC.
-1 Reset own Disk PPN to logged in PPN.
0,,n Return the Disk PPN of job n.
<proj>,,0 Set own Disk PPN to: <proj>,,<logged in prog. name>.
<proj>,,<prog> Set own Disk PPN to that in AC.

The DSKPPN UUO is used to change or retrieve your Disk
Project-Programmer Name or to retrieve the Disk PPN of someone else.
The action taken by this UUO is determined by the code in AC. If AC
contains zero, your current Disk PPN is returned in AC. If AC
contains -1, your Disk PPN is reset to your logged in PPN. If AC
contains a job number, the Disk PPN for that job is returned; if the
job is not logged in, zero is returned. If the right half of AC
contains zero and the left half is non-zero, then the PROJECT part of
your Disk PPN is set to the project specified by AC left and the
PROGRAMMER part is set to the programmer code under which you are
logged in. If both halves of AC are non-zero and AC doesn't contain
-1, then your Disk PPN is set to the PPN specified by the whole AC.
No error checking is done to make sure AC holds a legal or existing
PPN.

2.8 Initializing a Device

There are two UUOs available to initialize a device: the INIT UUO and
the OPEN UUO. Either of these UUOs can be used; the only difference
between them is the format for passing parameters to the system.

Each of these UUOs tells the system what device you want to use, what
2.8 Initializing a Device General I/O 19

mode you want to use it in, where your buffer headers are, if any,
and what channel number you want to associate with the device. If
the device is a non-sharable device (such as the line printer, a
terminal, a dectape or a magnetic tape) which is not available now,
the system will normally type out a message asking if you will wait
for it. However, the following bits in the data mode half word which
you specify when you attempt to initialize the device can be used to
indicate special action to be taken.

BITS OCTAL MEANINGS OF 1'S IN THE INITIAL DATA MODE

26 0,,1000 Wait automatically until the device is
available.

27 0,,400 Take error return automatically if the
device is busy. This bit takes
precedence over bit 26.

If you want to have your program wait automatically without your
being asked, you should have bit 26 (the 1000 bit) on in the data
mode half word. If you would like to get the error return
automatically when a device is busy, you should have bit 27 (the 400
bit) on in the data mode. The automatic error return bit takes
precedence over the automatic wait bit. Note that these two bits (26
and 27) are among those reserved for device-dependent features.
Thus, if you have either of these bits on when you initialize a
device, you should use the SETSTS UUO (explained in Section 2.14) to
turn them off after you get the device unless you want the particular
features they represent for that device. See the device writeups in
Section 13 for the meanings of these bits for the individual devices.

A device can be referred to by either its PHYSICAL name or its
LOGICAL name. The physical name of a device is the permanent name
given that device by the system. A logical device name is a
temporary name that can be specified with the monitor ASSIGN command.
Device names (physical or logical) are stored left-justified in
sixbit representation. For example, the device DTA1 is represented
by the octal number 446441210000, which can be set up by the SIXBIT
pseudo-op in the assembly languages, i.e., SIXBIT /DTA1/. If a given
device name is both a physical name (of one device) and a logical
name (of another device), the logical name takes precedence.
2.8 Initializing a Device General I/O 20

INIT [OP=041]
--------------------------------------------------
INIT <channel number>,<data mode>
<physical or logical device name in sixbit>
OBUF,,IBUF
<error return>

The INIT UUO initializes the named device on the channel indicated by
the AC field and in the data mode specified by the address field of
the instruction. OBUF should be the address for your output buffer
header or zero if none. IBUF should be the the address for your
input buffer header or zero if none. If you are not going to do any
buffered output on this channel, OBUF can be zero. If you are not
going to do any buffered input on this channel, IBUF can be zero.

The data mode half word is used to set the right half of the device
I/O status word for this device. The IOACT bit, however, is masked
out when this is done. (The device status word is explained in
Section 2.6.)

When you initialize a device, any device open on the channel
specified is released before the new device is initialized. (See the
RELEAS UUO in Section 2.12.)

If there is no device with the name you give, the error return
(double skip) is taken. If this UUO is successful, the triple skip
return is taken.

OPEN [OP=050]
--------------------------------------------------
OPEN <channel number>,ADR
<error return>

ADR: <data mode>
<device name in sixbit>
OBUF,,IBUF

The OPEN UUO does exactly the same thing as the INIT UUO above. The
difference is that the information passed to the system by OPEN does
not have to appear in line with the instruction stream. The location
of this information is specified by the effective address of the UUO.
Hence OPEN can be used by reentrant programs that change the data
referenced by the UUO.

The left half of the data mode word is ignored.
2.9 Setting Up Buffer Rings General I/O 21

2.9 Setting Up Buffer Rings

For buffered I/O, a buffer ring must be set up in your core area.
Unless you issue an explicit buffer-creating UUO (described below),
or make the buffer ring yourself (very carefully!), the system will
set up a buffer ring for you when you first give an INPUT or OUTPUT
UUO. That is, if a device open in buffered mode has no associated
input (output) buffer ring when the first INPUT (OUTPUT) UUO is
given, the system will set up a two-buffer ring before carrying out
the normal function of the UUO. To do buffered input (output), you
must have given the address of the input (output) buffer header when
you initialized the device.

Whenever the system sets up a buffer ring for you, it places the ring
at the address contained in JOBFF in your job data area (see Appendix
4). You may cause your buffers to be set up anywhere in your core
image by temporarily changing JOBFF to point to the place where you
want the buffers to be. If there is not enough room between JOBFF
and JOBREL for the number of buffers you request, your core image is
automatically expanded to make room. After the ring is set up, JOBFF
is left pointing to the first word beyond the ring and your buffer
header is made to point to the first buffer in the ring.

The following UUOs cause a buffer ring to be set up, and they permit
specification of a non-standard number of buffers and non-standard
sizes.

INBUF [OP=064]
--------------------------------------------------
INBUF <channel number>,<number of buffers>

The INBUF UUO causes an input buffer ring to be set up in your core
area and to be associated with the specified channel. The effective
address of this UUO is interpreted as the number of buffers the ring
is to have. If the effective address is zero, two buffers are set up
(the same number of buffers you would get if you did not give this
UUO at all).
2.9 Setting Up Buffer Rings General I/O 22

OUTBUF [OP=065]
--------------------------------------------------
OUTBUF <channel number>,<number of buffers>

The OUTBUF UUO causes a ring of output buffers to be set up exactly
as INBUF does for input buffers.

UINBF [OP=704]
--------------------------------------------------
UINBF <channel number>,ADR

ADR: <number of buffers>
<number of words of data in each buffer> + 1

The UINBF UUO causes an input buffer ring to be set up in your core
area and to be associated with the specified channel. The effective
address points to a two word block. The first word of this block
contains the number of buffers to be in the ring (zero means two),
and the second word contains a number which is one greater than the
number of words of data in each buffer.

Some devices (including the disk) do not accept nonstandard buffer
sizes. Devices that will accept nonstandard sizes include terminals
and magnetic tapes. For other devices see the individual device
descriptions in Section 13.

UOUTBF [OP=705]
--------------------------------------------------
UOUTBF <channel number>,ADR

ADR: <number of buffers>
<number of words of data in each buffer> + 1

The UOUTBF UUO causes a ring of output buffers to be set up exactly
as UINBF does for input buffers.
2.9 Setting Up Buffer Rings General I/O 23

BUFLEN [OP=047, ADR=400042] CALLI 400042
--------------------------------------------------
MOVE AC,[<device name in sixbit, or channel number>]
BUFLEN AC,

The BUFLEN UUO tells you the standard buffer size for the device
specified by the contents of AC. AC should contain either the name
(logical or physical) of the device or the number of the channel on
which it is open. The buffer size, which is returned in AC, is one
greater than the length of the data portion of a buffer that would be
set up if you did an INIT and then an INBUF or OUTBUF for the
particular device. This is the number you would need to use to set
up a standard size buffer with a UINBF or a UOUTBF UUO. The total
number of words each buffer would take up is two greater than this
number (see Section 2.5). If there is no such device, zero is
returned in AC.

2.10 Opening Files

After initialization of a directory device, a particular file on the
device must be opened (i.e., selected) before any I/O can take place.
Opening of a file for input is done with the LOOKUP UUO; opening of a
file for output is done with the ENTER UUO. The RENAME UUO is
available for changing a file's name or specifications (date written,
protection, etc.) after the file has been opened. RENAME is also
used to delete files.

If you initialize a directory device and attempt to transfer data
with an INPUT (OUTPUT) UUO without having done a LOOKUP (ENTER), the
system will type out a message and require you to type in a filename
so that a LOOKUP (ENTER) can be done before the data is transferred.

For non-directory devices, the UUOs LOOKUP, ENTER and RENAME are
no-ops; they always take the success (skip) return.
2.10 Opening Files General I/O 24

LOOKUP [OP=076]
--------------------------------------------------
LOOKUP <channel number>,ADR
<error return>

ADR: <file name in sixbit>
<file name extension in sixbit>
<this word is ignored>
<project-programmer name in sixbit>

The LOOKUP UUO opens for input the file specified by the four-word
block pointed to by the effective address of the UUO. The first word
of the block should contain the sixbit name of the file to be read;
the second word should contain the sixbit file name extension in the
left half. If the device is the disk, the fourth word of the block
should contain the project-programmer name for the file or zero; zero
will cause your current Disk PPN to be assumed for the file (see page
17). The right half of the file extension word is ignored as is the
whole word following the extension word. For dectapes the
project-programmer name is also ignored.

If the LOOKUP is successful, the skip return is taken and some
information about the file is returned. If the file does not exist
or if some other error condition arises, then the error return (no
skip) is taken and, if the device is the disk, an error code is
returned in the right half of ADR+1 (the rest of the block is
unchanged). The error codes for LOOKUP, ENTER and RENAME are
explained in a table on page 29. No error codes are returned for
dectapes.

After a successful LOOKUP of a disk file, the following information
is returned in the LOOKUP block. The word at ADR+2 contains: the
file's protection in bits 0:8 (777000,,0 bits) the data mode in which
the file was written in bits 9:12 (740,,0 bits), the file's time
written in bits 13:23 (37,,770000 bits), and the file's date written
in bits 24:35 (0,,7777 bits). These values are stored in the
directory when the file is created and may be changed with the RENAME
UUO (see page 26). (The date written is in system date format which
is explained under the DATE UUO on page 95. The time written is in
minutes past midnight on the date given. The protection bits are
explained on page 16 and the data mode is explained in Section 2.2.)
The word at ADR+3 contains the negative swapped word count, that is,
the negative of the number of words in the file, with the left and
right halves exchanged. (The word count is returned in this strange
format to be compatible with DEC's format.) Finally, the right half
of the word at ADR+1 contains, in system date format, the "creation
date" of the file, which is a slightly less than well defined
quantity. The date written in ADR+2 is a much more significant date.
2.10 Opening Files General I/O 25

Here is a summary of the information in the block after a successful
LOOKUP on the disk.

ADR: <file name>
ADR+1: <file name extension>,,<"creation date">
ADR+2: <Bits 0-8 (777000,,0 bits): protection;
bits 9-12 (740,,0 bits): data mode;
bits 13-23 (37,,770000 bits): time written;
bits 24-35 (0,,7777 bits): date written>
ADR+3: <negative swapped word count>

WARNING! You may not do two consecutive successful LOOKUPs for the
disk with the same four-word block without restoring the
project-programmer name in the fourth word of the block after the
first LOOKUP! The negative swapped word count probably will not
represent the PPN you want!

After a successful LOOKUP on a dectape, the following information
will be found in the LOOKUP block:

ADR: <file name>
ADR+1: <extension>,,<number of first block of file>
ADR+2: <date file written>
ADR+3: <value from 4th word of ENTER block when file was created>

ENTER [OP=077]
--------------------------------------------------
ENTER <channel number>,ADR
<error return>

ADR: <file name in sixbit>
<file name extension in sixbit>,,<creation date>
<protection key in bits 0:8 (777000,,0 bits)>
<project-programmer name>

The ENTER UUO opens for output a new file with the specifications
given in the four-word block pointed to by the effective address of
the UUO as indicated above. For a disk file, the time and date
written are set to the current time and date when the ENTER is done,
and the file's protection is set from bits 0:8 of ADR+2. If the
device is a dectape, the words at ADR+2 and ADR+3 are copied into the
dectape's directory with the exception that if bits 24:35 (0,,7777
bits) of ADR+2 are zero, the current date is substituted for this
12-bit field before the word is written into the directory. For the
disk, if the PPN is zero, your current Disk PPN is assumed. If the
ENTER is successful, the skip return is taken and exactly the same
2.10 Opening Files General I/O 26

information is returned in the block as after a successful LOOKUP
(see above and note that for a new file the word count is zero). If
there already was a file with the given name, its creation date is
returned; otherwise the specified creation date (zero means today) is
returned. If the ENTER fails for any reason, then the no skip error
return is taken and, if the device is the disk, a code is returned in
the right half of ADR+1 (the rest of the block is unchanged). The
error codes for LOOKUP, ENTER and RENAME with the disk are explained
in a table on page 29. No error codes are returned for dectapes.

An ENTER can fail for a number of reasons. It will fail if the file
name is zero, if the PPN (or Disk PPN) is illegal, if the file
already exists and is write protected against you, if the file is
already open for output (by anyone), if the device is a dectape which
is already full, or if you have already done a LOOKUP on this channel
and the filename for the ENTER does not agree with that given in the
LOOKUP (see Read-Alter mode for the disk on page 27).

With a successful ENTER of a disk file, if the file specified already
exists, then that file will be replaced with the new file WHEN THE
NEW FILE IS CLOSED. Until that time, any attempt to read the
specified file will access the old file. After the new file is
closed, any attempt to read the specified file will get the new
version; the old version will stay around only long enough for anyone
still reading it to finish.

RENAME [OP=055]
--------------------------------------------------
RENAME <channel number>,ADR
<error return>

ADR: <new file name or zero for deletion>
<new file extension>,,<ignored>
<new protection key, mode, time and date last written>
<project-programmer name>

The RENAME UUO is used to change the name, extension, protection key,
mode, or time and date written, or a combination of these, for a
file, or to delete a file. This UUO MUST be given AFTER a successful
LOOKUP or ENTER has been done on this channel and MAY be given after
a CLOSE UUO (see Section 2.12) for this channel. After an ENTER, a
CLOSE is NECESSARY before RENAME! As with LOOKUP and ENTER, if the
project-programmer name is zero, your current Disk PPN is assumed.

If the file name specified is zero, and if the effective PPN matches
the PPN of the file open on this channel, then that file is marked
2.10 Opening Files General I/O 27

for deletion. This means that as soon as no one is reading the file,
it will go away. (After a file has been marked for deletion, anyone
attempting to start reading it will not find it.)

If the file name is not zero, then the name, extension and protection
key for the file open on this channel are all changed to those
specified in the four-word block. Also, if bits 9:35 at ADR+2 are
not all zero, then the mode and time/date written of the file are set
to those specified by these bits (9:12 are mode; 13:23 are time;
24:35 are date). Note that you cannot rename a file to a different
disk area (different PPN); if the effective PPN is different from the
file's original PPN, the file will be lost.

If the RENAME is successful, the skip return is taken. Otherwise,
the no-skip error return is taken and (for the disk) an error code is
returned in the right half of ADR+1, with the rest of the block left
unchanged. The meanings of the possible disk error codes for LOOKUP,
ENTER and RENAME are explained in a table on page 29.

Read-Alter Mode

There are two basic methods of updating data in a file. In the
first, the file is copied, with appropriate changes, into a new file
with the same name. This is accomplished by doing a LOOKUP of the
old file on one channel and an independent ENTER of the same filename
on a different channel. When the new version of the file is closed,
the old version will be deleted (after all read references to it are
finished). This method requires the whole file, however, to be read
in and written out again even if only a little of the data in the
file is to be changed. The second method allows you to open an
already existing disk file and to change data in it IN PLACE, without
rewriting the whole file. This method of file manipulation is known
as READ-ALTER (RA) mode. When you have a file open in this mode, you
may do (on the same channel) both input and output with the file. To
open a file in this mode, you do a LOOKUP of the file and then an
ENTER of the same file on the same channel. If both the LOOKUP and
the ENTER are successful, then the file will be open in RA mode. If
you give a different filename for the ENTER than you used with the
LOOKUP, the ENTER will fail with an error code of 6 (see table
below). In RA mode, at the moment any data is written out, that data
overwrites whatever was there before. So if the file does not get
closed thereafter, the new data will still have replaced the old data
in the file. Data can be written into selected parts of a file by
use of the random access UUOs USETI, USETO and UGETF (see Section
2.13). While a file is open in RA mode, anyone attempting to do
either a LOOKUP or an ENTER of that file will get the FILE BUSY error
2.10 Opening Files General I/O 28

return (code 3, see below). Also, an attempt to open a file in RA
mode (by doing an ENTER after a successful LOOKUP) will also fail
with the FILE BUSY error return if anyone else is reading or writing
the file.
2.10 Opening Files General I/O 29

Disk Error Codes for LOOKUP, ENTER and RENAME

CODE MEANING

0 NO SUCH FILE.
LOOKUP: File specified does not exist.
ENTER: Zero file name given.
RENAME: File LOOKUPed or ENTERed no longer exists.

1 ILLEGAL PPN. PPN specified has no UFD.

2 PROTECTION VIOLATION. File is protected from what you
tried to do.

3 FILE BUSY.
LOOKUP: File is currently open in Read-Alter mode.
ENTER: File is currently being written.
ENTER after LOOKUP: File is currently being read or written.
RENAME: File is currently being read.

4 FILE ALREADY EXISTS. (RENAME only)
RENAME: There is already a file with the new name given.

5 NO FILE OPEN. (RENAME only)
RENAME: No successful LOOKUP or ENTER has been done yet.

6 DIFFERENT FILENAME SPECIFIED. (ENTER only)
ENTER: The filename does not match that of a LOOKUP
already done on this channel (attempt to open
file in Read-Alter mode).

7 (This error code cannot occur.)

10 BAD RETRIEVAL. Some disk pointers have been garbaged
somewhere. This should not happen.

11 BAD RETRIEVAL. Slightly different version of above.

12 DISK IS FULL. (ENTER only)
ENTER: There is no more room on the disk.

Note: Errors 10, 11 and 12 will cause a system error message to be
typed out unless bit 28 (the 0,,200 bit) is on in the device status
word (see Section 2.6). When one of these error messages is typed
out, the program will be stopped; if you then type CONTINUE, the
error return will be taken with the appropriate error code given.
2.11 Transferring Data General I/O 30

2.11 Transferring Data

The following UUOs are used to transfer data between your core image
and a device, which must already have been initialized on some
channel (see Section 2.8). If you give one of these UUOs for a
device open in buffered mode with no buffer ring set up, a two-ring
buffer will be set up for you before the normal action of the UUO is
taken (see Section 2.9).

IN [OP=056]
--------------------------------------------------
IN <channel number>,ADR
<success return>
<error return>

The IN UUO causes some data to be read in to your core image from the
device open on the given channel. In buffered mode, at least one
buffer will be filled with input data and the buffer header will be
updated so that the byte pointer and byte count are correct for the
newly filled buffer. In dump mode, ADR is taken to be the address of
a dump mode command list (see Section 2.3), and the UUO will not
return until all the data indicated by the command list has been
transferred. In buffered mode, ADR is ignored.

If any error (including end of file) occurs, then the UUO skips.
Specifically, when the UUO is to return, if any of the error bits
IOBKTL, IODTER, IODERR, IOIMPM or IODEND (see Section 2.6) are on,
the skip return is taken. Otherwise, the direct return (no skip) is
taken.

In dump mode, if end of file occurs before the command list has been
satisfied, then IODEND will come on and the UUO will skip, but there
will be no way of telling how much data, if any, was read in before
end of file occurred. In buffered mode, there is always a byte count
that tells how much data has been read in.

On teletypes and pseudo-teletypes, end of file is indicated by typing
control-Z (↑Z); on Data Disc and III displays, end of file is
indicated by typing control-meta-linefeed.
2.11 Transferring Data General I/O 31

INPUT [OP=066]
--------------------------------------------------
INPUT <channel number>,ADR

The INPUT UUO does exactly the same thing as the IN UUO except that
no error checking is done and the UUO never skips.

OUT [OP=057]
--------------------------------------------------
OUT <channel number>,ADR
<success return>
<error return>

The OUT UUO causes some data to be written out from your core image
to the device open on the given channel. In buffered mode, the
buffer pointer, byte pointer and byte count in the buffer header are
set up for the next buffer that you may fill and the device is
started up to empty the buffer you just filled. The first OUT UUO
you give in buffered mode, however, does not cause any data to be
written out, only the buffer header to be set up with the buffer
pointer, byte pointer and byte count for the first buffer for you to
fill.

In dump mode ADR is taken as the address of a dump mode command list
(see Section 2.3) that indicates what data are to be written out; the
UUO does not return until the transfer is complete.

In buffered mode, if ADR is non-zero, this UUO does NOT write out
your current buffer but instead switches you to the new buffer ring
pointed to by ADR. (ADR should be the address of the second word of
a buffer in the ring.) Your buffer header and some internal system
data are adjusted so that you will next be filling the first buffer
in the new ring. The buffer ring you are switching to must be
completely set up with the buffer-to-buffer pointers and the buffer
sizes in the second word of each buffer. The purpose of this feature
is to let you switch among several output buffer rings if you so
desire. Note, however, that when you switch rings there is no
provision for forcing data still in buffers in the old ring to be
written out.

As with the IN UUO, if any of the error bits IOBKTL, IODTER, IODERR,
IOIMPM or IODEND (see Section 2.6) are on at completion of the UUO,
the UUO skips. Otherwise, the direct return (no skip) is taken.
2.11 Transferring Data General I/O 32

OUTPUT [OP=067]
--------------------------------------------------
OUTPUT <channel number>,ADR

The OUTPUT UUO does exactly the same thing as the OUT UUO except that
no error checking is done and the UUO never skips.

WAIT [OP=047, ADR=10] CALLI 10
--------------------------------------------------
WAIT <channel number>,

The WAIT UUO simply waits for all I/O on the channel indicated by the
AC field to finish. Normally, when a device is open in buffered
mode, the system does I/O with your buffers while your program is
running. This means that only the buffer pointed to by your buffer
header can be expected to be remain untouched by the system. After
giving this UUO, you can expect all of your buffers to be stable and
untouched by the system.

2.12 Terminating I/O

The following two UUOs are used to finish up I/O on a given channel.
The CLOSE UUO essentially undoes the effect of a LOOKUP or ENTER, and
the RELEAS UUO undoes the effect of an INIT or OPEN.

CLOSE [OP=070]
--------------------------------------------------
CLOSE <channel number>,<close-inhibit flags>

(<close-inhibit flags>:
1 (bit 35) inhibits closing output,
2 (bit 34) inhibits closing input.)

The CLOSE UUO is used to terminate I/O on the channel specified by by
AC field of the UUO. The effective address of the instruction
determines whether input or output or both or neither is closed. If
the low order bit (bit 35--the 0,,1 bit) of the effective address is
on, then the closing of output is inhibited. If bit 34 (0,,2 bit) of
the effective address is on, the closing of input is inhibited. The
remaining bits in the effective address are ignored.
2.12 Terminating I/O General I/O 33

On non-directory devices like terminals and paper tape, this UUO
forces out any data still in any output buffers. For magnetic tape,
closing output causes two end-of-file marks to be written on the tape
and causes the drive to backspace over one of them; this means that
there will be one end-of-file mark between each pair of files and two
end-of-file marks after the last file on the tape. The two
consecutive end-of-file marks denote what is called the logical (as
opposed to physical) end of tape.

On the disk and dectape, closing output forces out any data still in
any output buffers and then closes the file; closing input simply
closes the file. After a disk or dectape file is closed, no more
data may be transferred to or from it. However, a file may be
RENAMEd even after it is CLOSEd.

RELEAS [OP=071]
--------------------------------------------------
RELEAS <channel number>,<close-inhibit flags>

(<close-inhibit flags>:
1 (bit 35) inhibits closing output,
2 (bit 34) inhibits closing input.)

The RELEAS UUO does a CLOSE of the given channel with the given
<close-inhibit flags> specified by the effective address (see the
CLOSE UUO above) and then frees the channel number. Thus, after
giving this UUO, you must do another INIT or OPEN to do any more I/O
on this channel.

The RESET UUO (see page 139) simulates a RELEAS <channel>,3 for every
channel you have open. The normal EXIT UUO (that is, "EXIT 0,")
simulates a RELEAS <channel>,0 for every channel you have open (see
page 138).

REASSI [OP=047, ADR=21] CALLI 21
--------------------------------------------------
MOVE AC,[<job number>]
MOVE AC+1,[<device name in sixbit, or channel number>]
REASSI AC,

The REASSI UUO is used to turn over a device you are using to another
job. Accumulator AC should contain the number of the job to whom you
wish to give the device, and accumulator AC+1 should contain the
2.12 Terminating I/O General I/O 34

logical or physical name of the device or the channel on which it is
open. This UUO gives the same results as the following sequence:
1) you release the device with BOTH input and output inhibiting,
2) you deassign the device with the monitor DEASSIGN command, and
3) the job indicated assigns the device with the monitor ASSIGN
command.

If the job number you give is not that of a logged in job, then this
UUO will return with accumulator AC set to zero. If the device is
not assigned to your job, or if the device may not be reassigned at
this time, then the UUO will return with accumulator AC+1 set to zero
(which might be confusing if you specified channel zero in AC+1).

2.13 Random Access to Files

A disk or dectape file consists of a series of 200 word records.
Often, these records are read (or written) sequentially from the
beginning of the file to the end. But sometimes one wishes to read
or alter only selected parts of a file. Three random access UUOs are
provided to allow the user to do exactly that. To do random access
input or output, you must specify which record you want to reference
next. On the disk, the records of a file are numbered consecutively
from 1 to n, where the file is n records long. (HIDDEN records can
precede logical record 1 of a disk file. The hidden records have
non-positive logical record numbers. See the disk file record offset
feature on page 157.) On dectapes the records of a file are physical
blocks and are numbered differently; for a precise explanation of
dectape files, read Section 13.5.

For each disk file open, the system maintains a pointer to the record
that will be referenced by the next INPUT or OUTPUT UUO. For each
dectape file open, the system maintains two pointers, one for input
and one for output. The following three UUOs set these pointers to
specific values. If you try to set the record pointer for a disk
file to a value less than that of the first physical record in the
file, you get the first physical record instead. If you try to set
it to a record beyond the end of a disk file, you get the first
record after the last record in the file (and IODEND in the device
status word is turned on; see Section 2.6). If you try to set it to
a value greater than the number of the last physical block on a
dectape, IOBKTL will be turned on in the device status word; thus the
error return will be taken with the next IN or OUT UUO.
2.13 Random Access to Files General I/O 35

USETI [OP=074]
--------------------------------------------------
USETI <channel number>,<record number>

The USETI UUO prepares you to read from a file at a specific record.
You must have a file open for input on the channel indicated by the
AC field. The record pointer for the file (input block pointer for
dectape files) is set to the value in the address field of the
instruction and the status of any input buffers is set to unused.
The IODEND bit in the device status word is cleared unless you have
selected a record beyond the end of a disk file.

Note that the record number in a USETI for the disk is taken as a
signed 18-bit number in twos-complement notation; see the record
offset feature on page 157.

USETO [OP=075]
--------------------------------------------------
USETO <channel number>,<record number>

The USETO UUO prepares you for writing into a file at a specific
record. You must have a file open for output on the channel
indicated by the AC field. This UUO forces out the data in any
output buffers that have not yet been written and then sets the
record pointer for the file (output block pointer for dectape files)
to the value in the address field of the instruction. The status of
any output buffers is set to unused.

Note that the record number in a USETO for the disk is taken as a
signed 18-bit number in twos-complement notation; see the record
offset feature on page 157.

UGETF [OP=073]
--------------------------------------------------
UGETF <channel number>,ADR

The UGETF UUO prepares you to extend the file open on the given
channel. It forces out the data in any output buffers that have not
yet been written. Then, for the disk, the record pointer is set to
the number of the record after the last record of the file and IODEND
is turned on. For dectapes, the output block pointer is set to the
number of the next free block you may write on. In either case, the
2.13 Random Access to Files General I/O 36

number of the record (or block) so selected is returned in the word
pointed to by the effective address of the UUO. The status of any
input or output buffers is set to unused.

2.14 I/O Status Testing and Setting

There are various pieces of information one can find out about an I/O
device or about a logical I/O channel, namely: the I/O device status
bits (explained in detail in Section 2.6), the channel use bits
(explained below), the device characteristics (explained below), the
physical name of a device, and the number of people waiting to use a
given device. This section describes the UUOs used to get and/or set
these.

GETSTS [OP=062]
--------------------------------------------------
GETSTS <channel number>,ADR

The GETSTS UUO puts the I/O device status word for the device open on
the indicated channel into the word located at ADR. See Section 2.6.

SETSTS [OP=060]
--------------------------------------------------
SETSTS <channel number>,<status bits>

The SETSTS UUO waits for the device open on this channel to become
inactive and then sets the right half of the I/O device status word
for this device from the address field of the UUO. See Section 2.6.

STATZ [OP=063]
--------------------------------------------------
STATZ <channel number>,<status bits to be tested>
<return if any of the indicated bits are on>
<return if all indicated bits are off>

The STATZ UUO tests certain bits in the right half of the status word
for the device open on the indicated channel. The address field of
2.14 I/O Status Testing and Setting General I/O 37

the UUO should contain 1's in the bit positions to be tested. If all
of the tested bits are off (zero), then this UUO skips. If any of
them are on, the direct return is taken.

STATO [OP=061]
--------------------------------------------------
STATO <channel number>,<status bits to be tested>
<return if all indicated bits are off>
<return if any of the indicated bits are on>

The STATO UUO tests bits in the right half of the status word just
like STATZ does but skips if any of the tested bits are on and does
not skip if all of them are off.

CHNSTS [OP=716]
--------------------------------------------------
CHNSTS <channel number>,ADR

The CHNSTS UUO puts the use bits for the I/O channel indicated into
the word located at ADR. Here is a list of the meanings of these
bits.

BITS OCTAL NAME MEANINGS OF 1'S IN CHANNEL
USAGE WORD

18 0,,400000 INITB The channel has been
initialized with an INIT or an
OPEN and a RELEAS has not been
given yet.
19 0,,200000 IBUFB The INIT or OPEN which
initialized this channel
specified an input buffer
header address.
20 0,,100000 OBUFB The INIT or OPEN which
initialized this channel
specified an output buffer
header address.
21 0,,40000 LOOKB A LOOKUP (successful or not)
has been done on this channel.
22 0,,20000 ENTRB An ENTER (successful or not)
has been done on this channel.
23 0,,10000 INPB An INPUT or IN UUO has been
done on this channel.
2.14 I/O Status Testing and Setting General I/O 38

24 0,,4000 OUTPB An OUTPUT or OUT UUO has been
done on this channel.
25 0,,2000 ICLOSB The input side of this I/O
channel has been closed.
26 0,,1000 OCLOSB The output side of this I/O
channel has been closed.
27 0,,400 INBFB An input buffer ring has been
set up for this channel.
28 0,,200 OUTBFB An output buffer ring has been
set up for this channel.
29 0,,100 SYSDEV The device open on this
channel is SYS (i.e., disk
area [1,3]).

DEVCHR [OP=047, ADR=4] CALLI 4
--------------------------------------------------
MOVE AC,[<device name in sixbit, or channel number>]
DEVCHR AC,

The DEVCHR UUO returns the device characteristics word for the device
specified by the contents of AC. AC should contain either the name
(logical or physical) of the device or the number of the channel on
which it is open. The characteristics are returned in the AC. If
the device does not exist, a zero is returned. Here are the meanings
of the bits in the returned word.

BITS OCTAL MEANINGS OF 1'S IN DEVICE
CHARACTERISTICS WORD

0 400000,,0 Dectape with directory in core.
1 200000,,0 Disk.
2 100000,,0 User disk pack (UDP).
3 40000,,0 Line printer (LPT) or XGP. The LPT and
the XGP can be distinguished from each
other by checking bit 8 (long dispatch
table), which will be on for the XGP and
off for the LPT.
4 20000,,0 Terminal which is attached to a job.
5 10000,,0 Terminal which is in use.
6 4000,,0 TV camera.
7 2000,,0 The IMP.
8 1000,,0 Long dispatch table. This means that
the device will accept UUOs other than
INPUT and OUTPUT, such as MTAPE, USETO
and LOOKUP.
9 400,,0 Paper tape punch or plotter (which are
logically the same device).
2.14 I/O Status Testing and Setting General I/O 39

10 200,,0 Paper tape reader.
11 100,,0 Dectape.
12 40,,0 The device is available to the job that
gave the DEVCHR UUO.
13 20,,0 Magnetic tape.
14 10,,0 Terminal.
15 4,,0 Directory device. At Stanford, this
means the device is a dectape, the disk
or a UDP.
16 2,,0 Input device.
17 1,,0 Output device.
18 0,,400000 ASSIGNed device.
19 0,,200000 Some job has done an INIT or OPEN on
this device.
20:35 0,,177777 A one in bit 35-J means mode J is legal
for this device.

DEVUSE [OP=047, ADR=400051] CALLI 400051
--------------------------------------------------
MOVE AC,[<device name in sixbit, or channel number>]
DEVUSE AC,

The DEVUSE UUO can be used to find out what job, if any, is using a
device and how many jobs are waiting for that device. The AC should
contain the name (logical or physical) of the device or the channel
number on which it is open. If there is no such device, a zero is
returned in AC. Otherwise, the following information is returned in
AC:

BITS OCTAL VALUE

0 400000,,0 One if the device has been ASSIGNed by
monitor command.

1 200000,,0 One if a program has done an INIT or
OPEN on this device.

2 100000,,0 One if the device is a TTY attached to a
job.
2.14 I/O Status Testing and Setting General I/O 40

12:17 77,,0 Number of the job the device is being
used by, or zero if it is not in use.
If the device has been detached from the
system, then this field will contain
zero but bit 0 (ASSIGNed device, see
above) will be on.

18:35 0,,777777 The number of jobs (not including you)
in the queue waiting for the device.

PNAME [OP=047, ADR=400007] CALLI 400007
--------------------------------------------------
MOVE AC,[<device name in sixbit, or channel number>]
PNAME AC,
<error return for no such device>

The PNAME UUO returns the physical name of the device specified by
the contents of the AC. AC should contain either the device name
(logical or physical) or the number of the channel on which the
device is currently open. If the device exists, the skip return is
taken and the device's physical name is returned in AC. If there is
no such device, the direct (error) return is taken and the AC is
unchanged.

DEVNUM [OP=047, ADR=4000104] CALLI 4000104
--------------------------------------------------
MOVE AC,[<device name in sixbit, or channel number>]
DEVNUM AC,
<error return for no such device>

The DEVNUM UUO is used to find out the unit number of a particular
device. AC should contain either the logical or physical name of the
device or the number of the channel on which the device is open. If
there is a device with the name given or open on the channel given,
then its unit number is returned in AC and the skip return is taken.
If there is no such device, the direct (error) return is taken.

The unit number of a device specifies which of several logically
identical devices a specific device is. For instance, the unit
number of TTY41 is 41, the unit number of MTA1 is 1, etc.
3. TTY I/O TTY I/O 41

SECTION 3

TTY INPUT/OUTPUT

The terminal is one of the most important I/O devices for the user.
He controls his programs by typing in various commands, and the
programs type back certain things to keep him informed. This section
explains several UUOs that are provided to make terminal I/O control
flexible but simple. The word TTY is used in this manual to mean a
user terminal of any type, whether display, teletype or
pseudo-teletype.

3.1 TTY Echoing and LF Insertion

The system provides two services to terminals doing input. The first
is that characters typed in are normally sent back to the terminal in
order for the user to see what he has typed. This is called echoing
of input. The second action taken on input is that normally, when
the system receives a carriage return from a TTY line, it inserts a
linefeed after the carriage return. Thus the user does not have to
type a linefeed (hereafter abbreviated LF) after each carriage return
(hereafter abbreviated CR). The LF is put into the terminal's input
buffer just as if the user had typed it; it is also usually echoed to
the terminal.

These actions can be modified by the user to suit his particular
purposes. Echoing can be turned off in two different manners. The
first of these is intended for terminals that always print each
character typed. If the system were to echo characters to this kind
of terminal, each character would appear twice. This method of
turning echoing off causes all echoing to be suppressed except for
echoing of LFs inserted after CRs. Bit 15 (4,,0 bit) in the line
characteristics word (see the GETLIN UUO on page 45) indicates the
state of this type of echo suppression. This bit can be set and
cleared by the monitor commands TTY NO ECHO and TTY ECHO,
respectively.

The second type of echo suppression is designed to be used by
programs that, for whatever reasons, do not want typed-in characters
to appear on the terminal. This method turns off all echoing except
when TTY input is going to the monitor rather than to the program.
The state of this type of echo suppression is indicated by the NOECHO
bit (bit 28--the 0,,200 bit) in the TTY I/O status word (see Section
3.1 TTY Echoing and LF Insertion TTY I/O 42

2.6 and Section 2.14); when the NOECHO bit is on, echoing is
suppressed. This bit can be turned on or off only by UUO, currently
only by the CTLV UUO (see page 53), by the PTJOBX UUO (with the DOFF
and DON functions--see page 63) and by the INIT and SETSTS UUOs.
PTJOBX is the recommended UUO for this purpose. A RESET (see page
139) clears this bit, thus turning echoing back on. (A program can
also disable just the echoing of the CONTROL and META bits; see the
NOECHB bit in Section 13.2.)

Insertion of linefeeds after carriage returns is affected by three
factors: 1) whether TTY input is going to the monitor or to a user
program, 2) whether the terminal is a pseudo-teletype (see Section
3.5), a display or a teletype, and 3) the value of bit 16 (2,,0
bit) in the TTY line characteristics word (see the GETLIN UUO on page
45). LFs are always inserted after CRs on III and Data Disc
displays. For other TTYs in the normal case, LFs ARE inserted after
CRs. They are NOT inserted if both 1) bit 16 in the line
characteristics word is on and 2) either the terminal is a
pseudo-teletype or input is going to a user program. Note that
pseudo-teletypes (PTYs) are initialized with bit 16 on; thus LFs are
normally NOT inserted after CRs on PTYs. Bit 16 in the
characteristics word can be changed only by UUO, currently only by
the SETLIN UUO (see page 48) and the PTSETL UUO (see page 62).

3.2 Codes Returned for Characters Typed

When a character is read from a TTY, the 7-bit Stanford ascii code
for that character is returned in bits 29:35 (0,,177 bits) (see the
Stanford ascii character set in Appendix 7); in addition, characters
read from displays are returned with the CONTROL and META keys
represented as bits 28 (0,,200--CONTROL) and 27 (0,,400--META).
Furthermore, when control-Z is typed on a teletype and read by any of
the UUOs described below, the value returned is 612, which is the
code for control-meta-linefeed from displays. Thus the end-of-file
character always appears as the same code regardless of the type of
terminal on which it was typed. Note that when characters are being
read from a TTY by means of the INPUT or IN UUOs described in Section
2, only 7 bits are returned for each character (the CONTROL and META
keys on displays are lost), and the EOF characters (control-Z and
control-meta-linefeed) do not appear as characters at all--they
merely set the EOF bit in the TTY I/O status word.
3.3 TTYUUO TTY I/O 43

3.3 TTYUUO

The most important UUO is probably TTYUUO (known some places as
TTCALL). This is an extended UUO with many different functions.
With a couple of exceptions, which are noted, these functions all
operate on the terminal attached to the job giving this UUO.

TTYUUO [OP=051]
--------------------------------------------------
TTYUUO <function number>,ADR

TTYUUO uses the accumulator field of the instruction to determine the
particular function to be executed. Each of these functions is
described separately below.

INCHRW [OP=051, AC=0] TTYUUO 0,
--------------------------------------------------
INCHRW ADR

The INCHRW UUO waits for a character to be typed and then returns the
character right-justified in the word at ADR.

OUTCHR [OP=051, AC=1] TTYUUO 1,
--------------------------------------------------
OUTCHR ADR

ADR: <ascii character>

The OUTCHR UUO types out the single ascii character represented by
the right-most seven bits of the word at ADR.
3.3 TTYUUO TTY I/O 44

INCHRS [OP=051, AC=2] TTYUUO 2,
--------------------------------------------------
INCHRS ADR
<return if no character has been typed>
<success return>

The INCHRS UUO looks to see if a character has been typed. Then, if
so, the character is returned in the word at ADR and the skip return
is taken. If no character has been typed, the direct return is taken
and the word at ADR is not changed.

OUTSTR [OP=051, AC=3] TTYUUO 3,
--------------------------------------------------
OUTSTR ADR

ADR: <asciz string>

The OUTSTR UUO types out the ASCIZ string that starts at location
ADR. (An ASCIZ string is terminated by the first null (zero) byte.)

INCHWL [OP=051, AC=4] TTYUUO 4,
--------------------------------------------------
INCHWL ADR

The INCHWL UUO waits until an entire line (ended by carriage return,
linefeed, altmode or a control character) has been typed and then
returns a single character right-justified in ADR. This is called
LINE MODE and should be used instead of CHARACTER MODE (as in INCHRW)
whenever possible. In character mode you cannot always backspace
over mistyped characters because your program may already have eaten
them up; in line mode you can backup as far as the last activation
character.
3.3 TTYUUO TTY I/O 45

INCHSL [OP=051, AC=5] TTYUUO 5,
--------------------------------------------------
INCHSL ADR
<return if no entire line has been typed yet>
<success return>

The INCHSL UUO looks to see if an entire line has been typed, and if
so, returns one character right-justified in ADR and takes the skip
return. If an entire line has not yet been typed, the direct return
is taken and ADR is not changed.

GETLIN [OP=051, AC=6] TTYUUO 6,
--------------------------------------------------
GETLIN ADR

The GETLIN UUO can be used to find out what terminal a job is
attached to, if any, and what the characteristics are for any
terminal. If the original contents of ADR are less than zero, then
the characteristics for your own terminal are returned in ADR. If
ADR originally contains the number of a TTY line (a number between
zero and the maximum legal TTY line number), the characteristics of
that terminal are returned in ADR. If ADR originally contains a
number greater than the maximum legal TTY line number, then zero is
returned in ADR.

If a job requests the line characteristics for its own terminal, and
if that job is detached, that is, not attached to any terminal, then
a -1 (all bits on) will be returned as the line characteristics. You
should check for this condition before testing any of the particular
bits or you will be deceived by a detached job.

If the characteristics word is not -1, then the right half contains
the line number of the terminal and the left half contains the
characteristics of the terminal, as explained below.

NOTE: If the terminal is a pseudo-teletype (see Section 3.5)
controlled directly or indirectly (through a chain of
pseudo-teletypes) by a Data Disc or III display, then the Data Disc
bit (bit 4--the 20000,,0 bit) or the III bit (bit 0--the 400000,,0
bit) will be on in the characteristics for the pseudo-teletype.
3.3 TTYUUO TTY I/O 46

BITS OCTAL MEANINGS OF 1'S IN TTY LINE
CHARACTERISTICS WORD

0 400000,,0 The terminal is a III display.

1 200000,,0 The terminal is the PDP-10 console
teletype (CTY).

2 100000,,0 Carriage returns are made into multiple
carriage returns in order to allow the
teletype carriage to reach the left
margin before the next character reaches
the teletype. This bit can be set and
cleared with the monitor commands
TTY FILL and TTY NO FILL, respectively,
and with the SETLIN and PTSETL UUOs (see
below and page 62). Data Disc and III
displays are not affected by this bit.

4 20000,,0 The terminal is a Data Disc display.

5 10000,,0 The terminal is a model 37 teletype.

6 4000,,0 The terminal is a pseudo-teletype (see
Section 3.5).

7 2000,,0 The terminal is an IMLAC.

8 1000,,0 The terminal is a pseudo-teletype and is
controlled by a job connected to the
IMP. This means the PTY's job is being
run through the ARPA network. This bit
can be set and cleared with the SETLIN
and PTSETL UUOs.

9 400,,0 Pseudo-teletype input wait will be
terminated by TTY input also (see the
PTRD1W UUO on page 58). This is the
PTYWAKE bit; it can be set and cleared
with the SETLIN and PTSETL UUOs.

11 100,,0 The terminal is in special activation
mode. This means that line mode input
will be activated by the characters
whose bits are 1's in the special
activation table. This bit can be set
and cleared with the SETLIN and PTSETL
UUOs. A RESET (see page 139) clears
3.3 TTYUUO TTY I/O 47

this bit, as well as resetting your
special activation table to the standard
special activation table. See the
SETACT UUO on page 50.

12 40,,0 The last character typed was a rubout,
and a backslash will be typed out when a
character that is not a rubout is typed.

13 20,,0 The terminal is in full-character-set
mode. When this bit is off, lower case
letters are automatically changed to
upper case. This bit can be set and
cleared with the monitor commands
TTY FULL and TTY NO FULL, respectively,
and with the SETLIN and PTSETL UUOs. On
displays this bit can be set by [ESC] F
and cleared by [BRK] F.

14 10,,0 The terminal is assumed not to have a
hardware tabbing mechanism. When this
bit is on, tabs get converted into the
appropriate number of spaces. This bit
can be cleared and set by the monitor
commands TTY TAB and TTY NO TAB,
respectively, and with the SETLIN and
PTSETL UUOs. Data Disc and III displays
are not affected by this bit.

15 4,,0 Echoing of input characters is inhibited
except for linefeeds inserted by the
system after carriage returns. This
inhibition is provided primarily to
avoid double echoing on terminals that
always print each character typed. See
Section 3.1. This bit can be set and
cleared by the monitor commands TTY ECHO
and TTY NO ECHO, respectively, and with
the SETLIN and PTSETL UUOs. Data Disc
and III displays are not affected by
this bit.

16 2,,0 Linefeeds will not be inserted after
carriage returns, except in monitor
mode. This bit always determines
whether linefeeds are to be inserted
after carriage returns on a
pseudo-teletype (PTY), regardless of
whether the PTY is in monitor mode. See
3.3 TTYUUO TTY I/O 48

Section 3.1. On Data Disc and III
displays, this bit does not inhibit
insertion of LFs; it merely inhibits
echoing of inserted LFs. This bit can
be set and cleared with the SETLIN and
PTSETL UUOs. A RESET (see page 139)
clears this bit except on PTYs.

SETLIN [OP=051, AC=7] TTYUUO 7,
--------------------------------------------------
SETLIN ADR

ADR: <line characteristics bits which you want on>

The SETLIN UUO allows you to change certain bits in the line
characteristics for your terminal. You are allowed to change only
bits 2, 8, 9, 11, 13, 14, 15 and 16 (101536,,0 bits). These bits in
your line characteristics word are set to their values in the word at
ADR. All other bits in the word at ADR are ignored.

RESCAN [OP=051, AC=10] TTYUUO 10,
--------------------------------------------------
RESCAN ADR ; ADR is ignored if it is zero

ADR: <word for returned character count>

The RESCAN UUO attempts to back up your TTY input buffer pointer to
the beginning of the previous monitor command typed in. By using
this UUO, a program started up by a monitor command can re-read the
command line that started it. In fact, this UUO can be given over
and over to read the command line several times. If this UUO is
given with a non-zero effective address, then the number of
characters over which the pointer is backed up is returned in the
word pointed to by the effective address.

WARNING: If more than a buffer full of characters have been typed
since the beginning of the last monitor command, then the characters
you get after giving this UUO will NOT be from the command. The
pointer into the buffer will simply have been set to the value it had
at the beginning of the command; the command itself may have been
overwritten by other text typed in more recently, in which case you
will be reading garbage after giving this UUO.
3.3 TTYUUO TTY I/O 49

CLRBFI [OP=051, AC=11] TTYUUO 11,
--------------------------------------------------
CLRBFI

The CLRBFI UUO clears your TTY input buffer. This is used mainly to
throw away any characters the user has typed ahead when a fatal error
occurs.

CLRBFO [OP=051, AC=12] TTYUUO 12,
--------------------------------------------------
CLRBFO

The CLRBFO UUO clears your TTY output buffer.

INSKIP [OP=051, AC=13] TTYUUO 13,
--------------------------------------------------
INSKIP <flag>
<return if no characters have been typed>
<success return>

The INSKIP UUO tells you if the user has typed anything which you
have not yet read. If the low order bit of the address field <flag>
is on, then this UUO checks for a whole line having been typed;
otherwise it checks for anything having been typed. If something has
been typed, then this UUO skips; if not, the direct return is taken.

INWAIT [OP=051, AC=14] TTYUUO 14,
--------------------------------------------------
INWAIT ADR

The INWAIT UUO just waits until a full line has been typed in. Then
if the address ADR is non-zero, the number of characters in the last
line re-edited (III and Data Disc terminals only) with a control-CR
or with a PTLOAD UUO (see page 62) is returned in the word at ADR.
In other words, if you give a PTLOAD UUO and then do an INWAIT ADR,
you will get in location ADR the number of characters in the
re-edited line. If you are not at a III or Data Disc display, or if
you did not re-edit a line somehow, the number placed in ADR will be
meaningless.
3.3 TTYUUO TTY I/O 50

SETACT [OP=051, AC=15] TTYUUO 15,
--------------------------------------------------
SETACT [OLD,,NEW]

OLD: <4 word block to receive the current activation table>

NEW: <4 word block to provide a new activation table>

The SETACT UUO is used to retrieve and/or change the activation table
used in special activation mode. An activation table consists of 4
words, with one bit for each character and a couple of extra bits
thrown in for some special effects. The first three words plus the
high-order 20 bits of the fourth word (total of 128 bits) specify
which characters are activation characters (bit 0 of first word
represents ascii 0, bit 1 represents ascii 1, etc.). The activation
characters are defined to be those characters whose bits are 1 in the
activation table. The meanings of the low order bits of the fourth
word are given below:

BITS OCTAL MEANING OF 1'S AT END OF FOURTH WORD

35 0,,1 Suppress activation on characters with
control bits except for those characters
that would activate without any control
bits. See also bit 33 below.

34 0,,2 Disable control-carriage-return from
giving back the last line typed.

33 0,,4 Always activate on characters that have
both CONTROL and META on, regardless of
setting of bit 35 above.

This UUO takes the current activation table and places it in the four
words at OLD, then sets up the new activation table from the four
words at NEW. If either address OLD or NEW is zero, the
corresponding function of this UUO is omitted. Thus if OLD is zero,
the old activation table is not returned, and if NEW is zero, the
(old) activation table is not changed.

Your special activation table is initialized by the system so that
all characters except letters and digits cause activation (when you
are in special activation mode). The precise value of the initial
special activation table is shown below.

777777,,777777 ;Activate on octal 0:43
777700,,037600 ;Activate on octal 44:57 or 72:100
000000,,374000 ;Activate on octal 133:140
000007,,600000 ;Activate on octal 173:177
3.3 TTYUUO TTY I/O 51

TTREAD [OP=051, AC=16] TTYUUO 16,
--------------------------------------------------
TTREAD ADR

ADR: <line number>

The TTREAD UUO allows you to read the microswitch keyboard bits of
any display's keyboard. The effective address in this instruction
specifies a location which should contain the TTY line number of the
keyboard you wish to read. If the line number specified is illegal,
then your line number is used. Then if the line is not on the
keyboard scanner (that is, if the line is not a III or Data Disc
display line), then this UUO is a no-op.

The keyboard bits are returned in the right half of ADR. The line
number minus 20 is returned in the left half of ADR.

OUTFIV [OP=051, AC=17] TTYUUO 17,
--------------------------------------------------
OUTFIV ADR

ADR: <five-character ASCII string>

The OUTFIV UUO is designed for sending special commands to IMLACs.
The effective address should point to a word containing a
five-character ASCII string. Characters from the string are sent to
the terminal until either a null byte is encountered or the fifth
character in the string has been sent. If the low order bit (bit
35--the 0,,1 bit) of the ASCII word is on, a 177 character will be
appended to the front of the string sent to the terminal.

The special feature of this UUO is that it insures that the
characters (including the 177) will be sent to the terminal without
any intervening characters. This prevents commands sent to IMLACs
from getting mixed up with normal typeout.
3.4 Miscellaneous TTY UUOs TTY I/O 52

3.4 Miscellaneous TTY UUOs

TTYMES [OP=047, ADR=400047] CALLI 400047
--------------------------------------------------
MOVEI AC,ADR
TTYMES AC,
<error return>

ADR: <number or physical name of destination tty>
ppcccc,,MESS ;where ppcccc is a 6-digit octal number

MESS: ASCII /...message.../

The TTYMES UUO can be used to type out an ASCII string on any
terminal. Unlike the OUTSTR UUO, TTYMES allows the message to start
in any byte of a word. The end of the message is indicated by a null
(zero) byte or by exhaustion of an explicit character count.

Upon call, AC should contain the address of a two word block. The
first word of this block should contain either the name (physical or
logical) of the destination terminal, e.g., SIXBIT /TTY21/, or the
number of the destination terminal, e.g., 21. The second word of the
block should contain in its right half the address of the ASCII
message. The first six bits of the left half (pp in the sample call
above) indicate the position (within the first word) of the first
character of the message in normal byte pointer format; that is, pp
is the number of bits to the right of the first byte of the message.
If the position field contains zero, then 44 is assumed; that means
the first byte of the word at MESS is the first character in the
message. The remaining twelve bits of the left half (cccc above) may
contain either the number of characters in the message or zero. If
the count field contains zero, then the count is effectively set to
infinity. Characters are sent to the destination until either the
character count runs out or a null (zero) byte is encountered in the
message. Thus, if you don't wish to calculate the length of your
message, you can use a zero count and a null byte at the end of the
message (i.e., use an ASCIZ string).

If you try to send a message to a nonexistent terminal, you get the
error return. You also get the error return if the message can't be
sent right now (for instance, if the TTY's output is being held)
unless the terminal is your own, in which case this UUO waits until
it can send the message.
3.4 Miscellaneous TTY UUOs TTY I/O 53

SNEAKW [OP=047, ADR=400063] CALLI 400063
--------------------------------------------------
SNEAKW AC,

SNEAKS [OP=047, ADR=400064] CALLI 400064
--------------------------------------------------
SNEAKS AC,
<return if no char is waiting for you>
<success return>

The SNEAKW and SNEAKS UUOs look to see if any characters have been
typed that have not yet been read. If there is such a character, it
is returned in the AC. SNEAKW always returns a character, after
waiting until there is one if necessary. SNEAKS never waits; if
there is a character present, it is returned and the skip return is
taken. Otherwise, SNEAKS does not change the AC and takes the direct
return.

Note that SNEAKW does not wait for a whole line to be typed, only one
character. Also, neither of these UUOs actually reads in a
character.

ACTCHR [OP=047, ADR=400105] CALLI 400105
--------------------------------------------------
ACTCHR AC,

The ACTCHR UUO (III and Data Disc displays only) waits for a line to
be typed and then returns in AC the character (including control
bits) that activated the last line re-edited with a control-CR or
with a PTLOAD UUO (see page 62).

If you are not on a III or Data Disc display, this UUO returns 0
without waiting for a line to be typed.

CTLV [OP=047, ADR=400001] CALLI 400001
--------------------------------------------------
CTLV

The CTLV UUO inverts the state of echoing of TTY input by the system.
Normally every character you type is sent back to your terminal by
3.4 Miscellaneous TTY UUOs TTY I/O 54

the system so that you can see what you have typed. If you give this
UUO when echoing is turned on (normal state), echoing will cease; and
if you give this UUO when echoing is turned off, echoing will resume.
The system always echoes characters typed in when the terminal is in
monitor mode. See Section 3.1.

TTYIOS [OP=047, ADR=400014] CALLI 400014
--------------------------------------------------
MOVE AC,[<job number or sixbit device name>]
TTYIOS AC,

The TTYIOS UUO returns the I/O status word of the device indicated by
the contents of the AC. If AC contains a logical or physical device
name, that device's status word is returned. If AC contains a job
number, then the status word of the terminal belonging to that job is
returned; if that job has more than one TTY, then there is no telling
which one's status word will be returned. The I/O status word is
returned in the AC; if there is no such device, -1 is returned. The
meanings of some bits in the right half of the device status word are
explained in Section 2.6. Other bits for specific devices are
explained in the device writeups in Section 13.

GETLN [OP=047, ADR=34] CALLI 34
--------------------------------------------------
GETLN AC,

The GETLN UUO is used to find out the physical name of the terminal
attached to your job. The name (in sixbit) is returned in AC. If
the job is detached, zero is returned.

3.5 Pseudo-Teletypes

The pseudo-teletype (PTY) is a special system concept designed to
allow users to have control of more than one job at a time. A PTY is
like a physical terminal in almost all respects. However, a PTY is
controlled by the job which created it, and no other job can access
it. To TYPE CHARACTERS ON A PTY, the controlling job does character
output to the PTY; and to SEE THE CHARACTERS TYPED OUT ON A PTY, a
job does character input from the PTY. If you send a new PTY the
character "L" followed by a carriage return and linefeed, a job will
3.5 Pseudo-Teletypes TTY I/O 55

begin logging in on the PTY. You can run programs and communicate
with the monitor through a PTY just as you can through a physical
terminal, but PTYs are controlled by program rather than by keyboard.
Thus, a single job (attached to a terminal or even detached) can
control one or more PTYs and hence one or more other jobs, which
themselves can control other PTYs.

Just as each physical terminal has a unique line number, so does each
PTY. Currently the line numbers assigned to PTYs begin with 121 and
go upward. The PTYs have physical device names, just like other
terminals; for example, the physical name the PTY on line 121 is
SIXBIT /TTY121/. There is a maximum number of PTYs that the system
can support at any one time and this maximum is currently 24.

PTYs have line characteristics just as other terminals do (see the
GETLIN UUO on page 45). When a PTY is initialized (with the PTYGET
UUO), it is set up with the following bits on in the characteristics
word: 6--PTY, 10--(this bit is used by the system) and 16--linefeeds
are not inserted after carriage returns. You can of course change
certain bits in the characteristics word to suit your purposes. This
can be done for a PTY with the PTSETL UUO (see page 62) just as
SETLIN (see page 48) does it for other terminals.

When you output characters to a PTY, those characters will be echoed
by the monitor as usual and will thus appear in subsequent inputs
that you do from the PTY. You can turn off the automatic echoing by
the usual means for doing so with terminals; namely, you can turn on
bit 15 in the PTY's line characteristics, (this inhibits echoing so
that only linefeeds inserted after carriage returns get echoed), or
you can have the job that is running on the PTY do a CTLV UUO (see
page 53), which eliminates all echoing except while the PTY is in
monitor mode. You can get the same effect as doing a CTLV (to turn
echoing off) but more easily by using the PTJOBX UUO with the control
function DOFF. This will always turn echoing off, whereas CTLV
inverts the state of echoing, turning it off when it is on and on
when it is off. The control function DON for PTJOBX can be used to
turn echoing back on. The PTJOBX UUO is explained on page 63.

PTYUUO

The UUO that is used to communicate with PTYs is PTYUUO, which has
many different functions that it can perform, including reading from
and writing on a PTY.
3.5 Pseudo-Teletypes TTY I/O 56

PTYUUO [OP=711]
--------------------------------------------------
PTYUUO <function number>,ADR

ADR: <PTY's line number>
<other data depending on the function>

PTYUUO is an extended UUO that uses the AC field to determine which
of many possible pseudo-teletype functions is to be executed. Each
of these functions (which are described in detail below) expects a
two word block to be pointed to by the address field of the
instruction. The right half of the first word of this block should
contain the line number of the pseudo-teletype for which the UUO is
intended (except with PTYGET which returns this line number). The
second word is a data word that is used or returned by the UUO.

Doing PTYUUOs to Physical TTYs

It is sometimes useful for a program to be able to type things into
its own TTY input buffer just as if the user had typed them. This
can be done with PTYUUO by specifying a PTY line number of zero in
the word at ADR. When this word is zero, the PTY function is
executed with your terminal instead of with a pseudo-teletype. Thus,
if you do output to a PTY with a line number of zero, the characters
will go to your terminal's input buffer (into your line editor if you
are on a III or Data Disc display) just as if you had typed them.

If bit 18 (the 0,,400000 bit) of the word at ADR is on for a PTYUUO,
the number in the remaining bits of the right half is interpreted as
the line number of a terminal and the PTY function is carried out for
that terminal. However, if you do not own the terminal, you must
have a privilege to do anything with it.

Any attempt to do input (PTRD1S, PTRD1W or PTRDS UUOs) from a
physical terminal's output buffer with either of the above two
methods will not work; the PTYUUO will simply be a no-op.

Now here are the individual PTYUUO functions.
3.5 Pseudo-Teletypes TTY I/O 57

PTYGET [OP=711, AC=0] PTYUUO 0,
--------------------------------------------------
PTYGET ADR
<return if no PTYs available>
<success return>

ADR: <PTY's line number and characteristics are returned here>

The PTYGET UUO gets you a pseudo-teletype and places its line
characteristics word (see the GETLIN UUO on page 45) in the location
pointed to by the effective address of the instruction (i.e., ADR).
This means that the PTY's line number will appear in the right half
of ADR and its characteristics will appear in the left half.

If a PTY is available, this UUO skips and the PTY is assigned to you.
If there are none available, the direct return is taken and you get
no PTY.

PTYREL [OP=711, AC=1] PTYUUO 1,
--------------------------------------------------
PTYREL ADR

ADR: <line number of PTY to be released>

The PTYREL UUO releases the pseudo-teletype whose line number is in
the right half of ADR. The job running on that PTY is killed, and
any PTYs it may have acquired are released.

The RESET UUO (see page 139) releases all pseudo-teletypes you own.

PTIFRE [OP=711, AC=2] PTYUUO 2,
--------------------------------------------------
PTIFRE ADR

ADR: <PTY's line number>
<count of free bytes is returned here>

The PTIFRE UUO returns to you in ADR+1 the number of free bytes left
in the input buffer of the PTY whose line number is in ADR. This is
the number of characters you may send to that PTY before its input
buffer is full. If you use a PTY output UUO that waits, and if you
send more that this many characters, you will have to wait until the
3.5 Pseudo-Teletypes TTY I/O 58

program running on the PTY reads some characters and makes room for
your output.

PTOCNT [OP=711, AC=3] PTYUUO 3,
--------------------------------------------------
PTOCNT ADR

ADR: <PTY's line number>
<count of characters in PTY's output buffer is returned here>

The PTOCNT UUO returns in ADR+1 the number of characters in the
output buffer of the PTY whose line number is in ADR.

PTRD1S [OP=711, AC=4] PTYUUO 4,
--------------------------------------------------
PTRD1S ADR
<return if no character is present>
<success return>

ADR: <PTY's line number>
<one 7-bit character is returned here>

The PTRD1S UUO looks to see if there are any characters in the output
buffer of the PTY whose line number is in ADR. If there are, one
7-bit character is read from there and returned in ADR+1 and the skip
return is taken. If there are no characters in the PTY's output
buffer, then a zero is returned in ADR+1 and the direct return is
taken.

PTRD1W [OP=711, AC=5] PTYUUO 5,
--------------------------------------------------
PTRD1W ADR

ADR: <PTY's line number>
<one 7-bit character is returned here>

The PTRD1W UUO reads one 7-bit character from the output buffer of
the PTY whose line number is in ADR and returns the character in
ADR+1. If there are no characters in the PTY's output buffer, this
UUO waits for the PTY to do some output and then returns the first
character.
3.5 Pseudo-Teletypes TTY I/O 59

If the PTYWAKE bit (bit 9--the 400,,0 bit) is on in the line
characteristics word for your terminal (see the GETLIN UUO on page
45), then this instruction will return when a character is typed
either on the PTY or on your terminal. If the first character typed
is from the terminal, a zero will be returned in ADR+1 and no
characters will have been read from either the terminal or the PTY.
In this manner, you may wait for either PTY or TTY input.

PTWR1S [OP=711, AC=6] PTYUUO 6,
--------------------------------------------------
PTWR1S ADR
<return if character not sent>
<success return>

ADR: <PTY's line number>
<9-bit character to be sent>

The PTWR1S UUO sends the 9-bit character right-justified in ADR+1 to
the PTY whose line number is in ADR. If the character can be sent,
the skip return is taken. If the PTY's input buffer is already full,
the character is not sent and the direct return is taken. The
CONTROL and META keys which display lines have are represented by bit
28 (0,,200--CONTROL) and bit 27 (0,,400--META) in ADR+1.

The [ESCAPE], [BREAK] and [CLEAR] characters (as available on Data
Disc and III display keyboards) can be sent with this UUO (or with
the PTWR1W UUO below) by having ADR+1 contain 0,,10042 for [ESCAPE]
or 0,,10041 for [BREAK] or 0,,10044 for [CLEAR]. Also, if bit 23
(0,,10000 bit) is on in ADR+1, then the character represented by the
low order 7 bits (if not 41, 42 or 44) will be sent to the PTY
preceded by the [ESCAPE] character; and if both bits 23 and 24
(0,,14000 bits) are on, then the character in the low order 7 bits
will be sent preceded by the [BREAK] character. In either of these
two cases, if the character in the low order 7 bits is not an
[ESCAPE] or [BREAK] keyboard command and is not either 41, 42 or 44,
then this UUO becomes a no-op, taking the skip return. Also, if the
PTY specified is not a display, then only the low order 7 bits (bits
29:35--the 0,,177 bits) of ADR+1 are used; no [ESCAPE] or [BREAK]
commands can be sent for teletypes. (Imlacs can send 8 bits; the
0,,200 bit on an Imlac means that this character should not be
checked against the special activation table even if the Imlac is in
special activation mode.)
3.5 Pseudo-Teletypes TTY I/O 60

PTWR1W [OP=711, AC=7] PTYUUO 7,
--------------------------------------------------
PTWR1W ADR

ADR: <PTY's line number>
<9-bit character to be sent>

The PTWR1W UUO sends the 9-bit character right-justified in ADR+1 to
the PTY whose line number is in ADR. If the PTY's input buffer is
already full, this UUO waits until there is room and then sends the
character.

This UUO interprets the character in ADR+1 exactly as the PTWR1S UUO
does. See the PTWR1S UUO above for the details of sending the
[ESCAPE], [BREAK] and [CLEAR] characters to a display's input buffer.

PTRDS [OP=711, AC=10] PTYUUO 10,
--------------------------------------------------
PTRDS ADR

ADR: <PTY's line number>
<address or byte pointer for returned string>

The PTRDS UUO reads all the characters that are in the output buffer
of the PTY whose line number is in ADR and returns these characters
as an ASCIZ string at the location indicated by ADR+1. If bits 6:17
(7777,,0 bits) in ADR+1 are not all zero, the word at ADR+1 is taken
as a byte pointer to be used to return the ASCIZ string, with the
byte pointer incremented before the first character is deposited.
(Before the byte pointer is used, the size field is set up for 7-bit
bytes and the index and indirect fields are cleared.) If bits 6:17
of ADR+1 are zero, the ASCIZ string is returned such that the first
byte is in the high-order 7 bits of the location pointed to by the
right half of ADR+1.
3.5 Pseudo-Teletypes TTY I/O 61

PTWRS7 [OP=711, AC=11] PTYUUO 11,
--------------------------------------------------
PTWRS7 ADR

ADR: <PTY's line number>
<address or byte pointer for string to be sent>

The PTWRS7 UUO takes the ASCIZ string specified by ADR+1 and sends it
to the PTY whose line number is in ADR. This UUO waits as necessary
until the whole string has been sent. If bits 6:17 (7777,,0 bits) of
ADR+1 are not all zero, then ADR+1 is taken as a byte pointer to be
used to access the string, with the byte pointer incremented before
the first character is loaded. (Before the byte pointer is used, the
size field is set up for 7-bit bytes and the index and indirect
fields are cleared.) If bits 6:17 are zero, the string is assumed to
start in the high-order 7 bits of the word pointed to by ADR+1.

PTWRS9 [OP=711, AC=12] PTYUUO 12,
--------------------------------------------------
PTWRS9 ADR

ADR: <PTY's line number>
<address or byte pointer for string to be sent>

The PTWRS9 UUO does the same as PTWRS7 except that the string sent is
not a standard 7-bit ASCIZ string, but a string of 9-bit characters
terminated by a zero (null) character. The two high order bits (400
and 200 bits) in each 9-bit character represent the CONTROL and META
keys, respectively, which Data Disc and III display keyboards have.
As with PTWRS7, ADR+1 can contain either a simple pointer to the
string or a byte pointer to it.

This UUO is important because octal code 003 (β or control-C) does
not mean control-C if you are sending this string to yourself (line
number in ADR set to zero) and you are at a III or Data Disc display.
The code representing control-C in that case is 600, which takes 9
bits to represent. The code 600 works as control-C for all PTYs, so
it can always be sent instead of 003 to stop a job. Note that you
must send TWO 600s (two control-C's) to stop a job immediately.
Another method for stopping a PTY is to use the PTJOBX UUO with the
HALT control function; see page 63.
3.5 Pseudo-Teletypes TTY I/O 62

PTGETL [OP=711, AC=13] PTYUUO 13,
--------------------------------------------------
PTGETL ADR

ADR: <PTY's line number>
<PTY's line characteristics word is returned here>

The PTGETL UUO returns in ADR+1 the line characteristics for the PTY
whose line number is in ADR. The meaning of the line characteristics
word is explained under the GETLIN UUO on page 45.

NOTE: If a pseudo-teletype is controlled directly or indirectly
(through a chain of pseudo-teletypes) by a Data Disc or III display,
then the Data Disc bit (bit 4--the 20,,0 bit) or the III bit (bit
0--the 400000,,0 bit) will be on in the characteristics word for the
pseudo-teletype.

PTSETL [OP=711, AC=14] PTYUUO 14,
--------------------------------------------------
PTSETL ADR

ADR: <PTY's line number>
<new line characteristics desired>

The PTSETL UUO sets the line characteristics for the PTY whose line
number is in ADR from the word at ADR+1. In the line characteristics
word, only bits 2, 8, 9, 11, 13, 14, 15 and 16 (101536,,0 bits) can
be changed by the user. Other bits in the word at ADR+1 are ignored.
See the GETLIN UUO on page 45.

PTLOAD [OP=711, AC=15] PTYUUO 15,
--------------------------------------------------
PTLOAD ADR

ADR: <PTY's line number--must be a display>
<address or byte pointer for string>

The PTLOAD UUO loads a display's line editor with the ASCII string
specified by the word at ADR+1. If the left half of ADR+1 is
non-zero, then ADR+1 is assumed to be a byte pointer to the string;
characters are picked up from the string with ILDBs, so the byte
pointer should point to the byte just before the string. The end of
3.5 Pseudo-Teletypes TTY I/O 63

the string is defined by the first occurrence of a null or an
activation character. The activation character, if any, is left on
the end of the string in the line editor; typing carriage return will
simply activate the line up to and including any activation
character. Note that if the string was terminated with a null, then
typing carriage return will activate the string but will not add a
carriage return to it. If you activate the re-edited line with
anything besides carriage return, the activation character will be
inserted in the line wherever you typed it.

This UUO only works if the line number at ADR specifies a III or Data
Disc display; otherwise this is a no-op. The normal use of this UUO
is with a zero at ADR, which selects your own line editor to be
loaded with the given string (provided you are at a display). After
giving this UUO, you may read input from the terminal to get the line
back with any changes that may have been made. See particularly the
INWAIT UUO on page 49 and the ACTCHR UUO on page 53 for special
features regarding re-edited lines.

PTJOBX [OP=711, AC=16] PTYUUO 16,
--------------------------------------------------
PTJOBX ADR
<error return for HALT and CONT--no job logged in>
<error return for CONT--job cannot be continued>
<success return for CONT>

ADR: <pseudo-teletype line number>
<index, or sixbit name, of control function>

Control functions:

Index Name Function Success Return
----- ---- -------- --------------
1 HALT Stop the pty's job. skips
2 CONT Continue the pty's job. double skips
3 DOFF Turn off echoing of input to pty. no skip
4 DON Turn on echoing of input to pty. no skip
5 LOGIN Log in a job on pty. skips
6 IWAITS Skip if pty waiting for input. skips

PTJOBX is the extended PTY job control UUO. Any one of several
control functions can be exercised over a PTY without sending it any
character strings. The control is exercised over the job running on
the PTY whose line number is in ADR; a zero line number means the
control is exercised over your own job. This is a good method for
turning on and off the echoing of input to your job.
3.5 Pseudo-Teletypes TTY I/O 64

The word at ADR+1 should contain either the index or the sixbit name
of the control function desired. The currently available control
functions are listed above with their names and indices.

The HALT function takes the skip return on success and the direct
(error) return if there is no job logged in on the PTY. If you HALT
your own job (PTY line 0) this way, your terminal is left in user
mode and you cannot type commands to the monitor; you must type
control-C to get out of this condition.

The CONT function takes the double skip return on success, the direct
return if there is no job logged in on the PTY, and the single skip
return if the job cannot be continued.

The DOFF and DON functions always take the direct return; DOFF sets
bit 28 (0,,200 bit) in the TTY I/O status word (thus turning OFF
echoing) and DON clears this bit (turning echoing back ON). See
Section 3.1 for the meaning of this bit.

The LOGIN function logs the PTY in under the PPN of the controlling
job and copies the controlling job's Disk PPN and privileges; the job
number of the new job is returned at ADR+1 and the skip return is
taken if the job gets successfully logged in. If there is already a
job logged in on the PTY, that job's number is returned in ADR+1 and
the direct return is taken. (This is a good way to find out the
number of the job logged in on a PTY.) If there is no job logged in
on the PTY but there are no job slots available, zero is returned in
ADR+1 and the direct return is taken.

The IWAITS function lets you find out if the PTY is waiting for
input. That is, if the PTY has returned to monitor level and needs a
monitor command typed to it, or if the job running on the PTY is
waiting for TTY input, then this function skips. Otherwise, the
direct return is taken.
4. Display Output Display Output 65

SECTION 4

DISPLAY OUTPUT

The availability of displays for output provides great flexibility
and convenience in many programs. This section explains several UUOs
that allow the user to determine what will appear on a display.
These UUOs include: the PPIOTs to select and position various PIECES
OF PAPER on your screen; the PGIOTs and UPGIOT to run display
programs on Data Discs and IIIs and to select from various PIECES OF
GLASS on IIIs; DDCHAN to acquire and manipulate extra Data Disc
channels; VDSMAP to select the sources for the picture on a Data Disc
display; ADSMAP to select the sound source to be connected to the
speaker associated with a given display; and a few other related
UUOs.

This section does NOT discuss how to program the III or Data Disc
display processors. These processors are explained in Appendix 1
and Appendix 2, respectively. However, since the two display
processors are somewhat different in their operation, I shall attempt
to explain for each how it works and how it interacts with the system
so that you can understand what the various UUOs are intended to do.
Some references are made to specific III or DD instructions; these
are all explained in the above-mentioned appendices.

4.1 III Displays

The III display processor runs continuously, executing display
instructions from main memory. The code it executes is located in
system free storage. Any change to a single word of this code will
cause the resultant display to change. A user-written III display
program can be run by using the UPGIOT UUO. (The III instructions
are explained in Appendix 1.) UPGIOT takes as arguments the
location and length of the display program to be run. The system
copies the display program out of the user's core image into free
storage, making transformations such as address relocation.

The system uses the first word in your program to interface with
other display programs; you MUST include an extra word at the
beginning of each III display program you write. To exit from the
middle of your display program, insert a HLT instruction. Otherwise,
you should simply plan to fall through to the end of your program.
You need not have a HLT at the end.
4.1 III Displays Display Output 66

Every job running on a III is permitted to have up to 20 independent
display programs. A III display program is called a piece of glass,
and each piece of glass (hereafter abbreviated POG) has a number
between 0 and 17 inclusive. RAID uses POG 17; please note the
obvious conflict if your program uses this POG too.

You may choose which of your pieces of glass are to be visible and
which are to be invisible. The display code for an invisible POG
continues to reside in system free storage but is simply not
executed; you may reactivate it at any time.

The only III instruction that is illegal in a user display program is
the JMS instruction. To get the effect of a JMS, use the JSR and/or
SAVE instructions (see Appendix 1).

You are not allowed to display anything on someone else's III unless
you are privileged. You may display on a III that is not in use.

4.2 Data Disc Displays

The Data Disc (DD) display processor works by storing complete TV
pictures bit by bit on a disk. The disk we have has =64 tracks; two
tracks are needed to hold a complete picture. Thus =32 complete TV
images can be stored on the Data Disc. Each combination of two
tracks that makes up a whole picture is called a Data Disc channel.
The Data Disc hardware reads the disk and puts out a TV signal for
each channel. Each TV signal can then be routed by the video switch
(controlled by software) to any combination of TV monitors (Data Disc
displays).

When the DD processor executes a program, the resultant picture
changes are recorded on the disk, and the displayed picture changes.
The Data Disc display processor does not execute the same display
program continuously like the III processor. The only way to make a
DD picture disappear is to explicitly erase it from the disk by means
of a DD program (from either the system or a user).

There is no such thing as a piece of glass on a DD display. Also,
you should NOT include an extra word at the beginning of a DD display
program as you do for III display programs; every word of a DD
display program is executed as a display instruction. (The DD
instructions are explained in Appendix 2).

More words of warning:

The DD processor executes your display program directly from your
4.2 Data Disc Displays Display Output 67

core image. No address relocation is done; thus jumps will not work
correctly since their destination addresses are taken as absolute!

Your Data Disc display program should end with a HALT instruction; if
it does not, the system will zero the last word of the program to
make sure it halts.

Finally, you may do a channel select only to your own main channel or
to an extra DD channel that you own or are permitted to write on. If
you have no channel select in the first 10 words of your DD program,
the system will select your main DD channel for you. (On the DD
display processor, only the first channel select in a program will
work; so any channel select beyond the first 10 words will be
ignored.) In addition, a select of channel 0 will get your main DD
channel. Thus to select the real channel 0, you select channel 40.
You see, 40 is non-zero so you don't get your main channel, but only
the low order 5 bits of the channel number are used in the select
(since there are only =32 channels). You can always select channel
40+C and be assured of getting channel C. However, if you select a
channel that you are not allowed to write on, the select is changed
to your own main channel. In all of these cases where the system
selects your own main DD channel for you, it does so by starting the
DD processor at a special two word block that contains a channel
select in the first word and a jump to your program in the second
word.

4.3 Page Printer Manipulation

Your page printer is the part of the monitor that prints text on your
display screen. Normally your entire screen is used by the page
printer. However, you may have up to 20 logical PIECES OF PAPER,
numbered from 0 to 17 inclusive, to which TTY output and echoing of
input may be directed, and each of these pieces of paper may be
placed at any part of the screen. You select the piece of paper
(hereafter abbreviated PP) which is to be used currently, and all TTY
printing and echoing will go to that PP until you select some other
PP. Initially, PP 0 is selected.
4.3 Page Printer Manipulation Display Output 68

PPIOT [OP=702]
--------------------------------------------------
PPIOT <function>,<argument>

PPIOT is an extended UUO that uses the AC field to determine which of
several page printer functions is to be executed. The individual
functions are described separately below.

PPSEL [OP=702, AC=0] PPIOT 0,
--------------------------------------------------
PPSEL <piece of paper number>

The PPSEL UUO selects the piece of paper whose number is the
effective address of the instruction. This number should be between
0 and 17, inclusive. Piece of paper number zero is the one normally
selected for you. After you give this UUO, all your TTY printing and
echoing will go to the specified piece of paper. This UUO
deactivates all other PPs as if you had done a PPACT UUO with only
this PP specified. See the PPACT UUO below.

PPACT [OP=702, AC=1] PPIOT 1,
--------------------------------------------------
PPACT <piece of paper activation map>

The PPACT UUO is used to display selected pieces of paper. The
effective address of the instruction is interpreted as a bit map
indicating which pieces of paper are to be displayed. A one in bit
18+N will cause PP number N to be displayed. Thus bit 18 (400000
bit) of the effective address is for PP 0, bit 19 (200000 bit) for PP
1, etc.

On the IIIs any PPs turned off by this UUO will disappear. However,
on the Data Discs those PPs will not disappear; you must erase them
explicitly if you no longer want them displayed.
4.3 Page Printer Manipulation Display Output 69

DPYPOS [OP=702, AC=2] PPIOT 2,
--------------------------------------------------
DPYPOS <Y-position>

The DPYPOS UUO causes the currently selected piece of paper to be
positioned on the screen so that its first line is located at the
Y-position specified by the effective address of this instruction,
where +1000 is the top of the screen and -1000 is the bottom.

DPYSIZ [OP=702, AC=3] PPIOT 3,
--------------------------------------------------
DPYSIZ <G*1000 + L>

The DPYSIZ UUO sets two values for the currently selected piece of
paper: the number of glitches (G) and the number of lines per glitch
(L). Both of these numbers are set from the effective address of the
instruction, G from bits 18:26 (0,,777000 bits) and L from bits 27:35
(0,,777 bits).

Now a word about glitches. When a piece of paper fills up, the text
in it jumps up to provide room for more text (thus moving some text
off the top of the PP). This jumping up is called a glitch. The
number of lines it jumps is the number of lines per glitch (L) as set
by the last DPYSIZ for this PP or by the default if no DPYSIZ has
been given. The total number of lines in a PP is L*G.

PPREL [OP=702, AC=4] PPIOT 4,
--------------------------------------------------
PPREL <piece of paper number>

The PPREL UUO releases the piece of paper whose number is the
effective address of the UUO. Piece of paper zero cannot be
released; PPREL 0 is a no-op. The system storage associated with a
PP being released is freed; you cannot possibly get back the text
that was on it. If you release the currently selected PP, a PPSEL
(see above) to piece of paper zero is done. On IIIs, released PPs
will disappear.
4.3 Page Printer Manipulation Display Output 70

PPINFO [OP=702, AC=5] PPIOT 5,
--------------------------------------------------
PPINFO ADR

ADR: <block 24 words long for returned information>

The PPINFO UUO gives you a 24-word table of information about your
page printer. The effective address in the instruction should point
to a 24-word block into which the table is to be placed.

The information returned in the table is indicated below, where PP
means piece of paper and PG means piece of glass. To get the same
information for some other job, use the PPSPY UUO (see page 72).

WORDS VALUE

0 <POG activation bits>,,<PP activation bits>
These are in PGACT and PPACT formats. See these two
UUOs.

1 <number of the currently selected PP>

2 Bit 0 (400000,,0 bit) is 1 if the Data Disc page color
is green on black.
Bit 1 (200000,,0 bit) is 1 if your screen has been
erased by an escape command since you last gave this
UUO.
Bit 2 (100000,,0 bit) is 1 if you are on a Data Disc
display.
Bits 18:35 (the 0,,777777 bits) hold your line editor
Y-position in LEYPOS format. See the LEYPOS UUO
below.

3:22 <Y-position>,,<G * 1000 + L>
There is one word here for each PP; in word 3 is the
status for PP 0, word 4 for PP 1, etc. The
<Y-position> is in DPYPOS format, G means number of
glitches, and L means lines per glitch. See the
DPYPOS and DPYSIZ UUOs above.
4.3 Page Printer Manipulation Display Output 71

23 Bit 0 (400000,,0 bit) is 1 if the size of the
currently selected PP was last set by keyboard command
rather than by UUO.
Bit 1 (200000,,0 bit) is the same for the Y-position
of the current PP.
Bit 2 (100000,,0 bit) is the same for the line hold
count.
Bit 3 (40000,,0 bit) is the same for the glitch hold
count.
Bits 9:17 (777,,0 bits) have the actual line hold
count.
Bits 18:26 (0,,777000 bits) have the actual glitch
hold count.
Zero in either of these hold counts means that that
hold count is not being used.
Bits 27:35 (0,,777 bits) hold the character (including
control bits) that activated the last line re-edited
with a control-CR or with a PTLOAD UUO (see page 62).

LEYPOS [OP=702, AC=6] PPIOT 6,
--------------------------------------------------
LEYPOS <Y-position for line editor>

The LEYPOS UUO sets the Y-position of your line editor to that
specified by the effective address of the instruction, which is
interpreted in DPYPOS format (+1000 is top of screen, -1000 is
bottom). A Y-position of zero does NOT mean the middle of the
screen, but instead means return the line editor to the bottom of
your page printer (its normal location).

PPHLD [OP=702, AC=7] PPIOT 7,
--------------------------------------------------
PPHLD <LHC*1000 + GHC>

The PPHLD UUO sets the line hold count (LHC) and the glitch hold
count (GHC) for your page printer. These two numbers indicate how
many lines or glitches the system should allow to be printed before
automatically holding the typeout for your display. Both the LHC and
the GHC are set from the effective address of the UUO, LHC from bits
18:26 (the 0,,777000 bits) and GHC from bits 27:35 (the 0,,777 bits).
If the high order bit of either of these fields is on, the
corresponding hold count is NOT changed. A zero in either field
disables that particular type of automatic holding.
4.3 Page Printer Manipulation Display Output 72

PPSPY [OP=047, ADR=400107] CALLI 400107
--------------------------------------------------
MOVE AC,[<job number or -tty number>,,ADR]
PPSPY AC,
<error return>

ADR: <24-word block for returned information>

The PPSPY UUO returns a 24-word block of information about the page
printer of a specific job or display. The information returned is
exactly the same as that returned by the PPINFO UUO (see page 70).
The right half of AC should contain the address of the 24-word block
where you want the information returned. The left half of AC should
contain either the number of the job or the negative of the number of
the display for which you want the page printer information. If this
UUO is successful, the skip return is taken. If there is no such job
or if the terminal is not a display, then the direct (error) return
is taken.

4.4 Running Display Programs

This section describes the UUOs that allow the user to have his own
display programs run on the III and Data Disc display processors.

UPGIOT [OP=703]
--------------------------------------------------
UPGIOT <piece of glass number>,ADR

ADR: <flags>,,<address of display program>
<length of display program in words>
<transfer-in-progress flag, if bit 0 in ADR is on>
<address of low order line command, if bit 1 in ADR is on>

The UPGIOT UUO (also known as DPYOUT) causes a display program to be
run. If you are on a Data Disc, the program is assumed to be a Data
Disc display program and thus is run on the Data Disc display
processor. If you are on a III terminal, the program is run on the
III display processor. If you are on a pseudo-teletype (PTY) which
is owned either directly or indirectly (that is, through a chain of
PTYs) by a job running on a display, then the program is run on that
display, whether it be III or Data Disc.
4.4 Running Display Programs Display Output 73

If the display program is to be run on a III, the AC field of the
instruction indicates which piece of glass the program is to be run
as. If the program is intended for a Data Disc display, the AC field
is ignored.

The address field of this UUO points to a data block, of which the
first word contains the address of the display program that is to be
run and the second word contains the program's length in words.

For Data Disc programs there are some other optional parameters which
you may specify. If bit 0 (400000,,0 bit) of the word at ADR is on,
then the display program is run in overlapped mode. This means the
UUO will return without waiting for the display program to finish.
(However, it will wait for any previous DD program to finish.) In
this mode the word at ADR+2 is set non-zero while the program is
being sent to the DD processor and is set to zero when the program
has finished. Thus you can test to see if the program has completed;
you should not change any part of the display program until ADR+2 has
been set to zero. Also, if you indicate a DD program length of zero
in ADR+1, no program will be run at all, but the UUO will not return
until any previous DD program has finished.

If bit 1 (200000,,0 bit) at ADR is on, the display program is run in
double field mode. This is useful for writing text on a Data Disc
channel. Normally you have to send text to the DD processor twice,
once for each of the two tracks that make up the DD channel. In
these two passes, you would indicate two line addresses that are the
same except in the low order bit position. In double field mode, the
system sends the program to the DD processor twice, once with the low
order bit of the line address select set to zero and once with it set
to one. The original value of this bit when you give the UUO is
irrelevant and its final value is unspecified. The low order line
address select must occur as the third command in the word pointed to
by ADR+3. This feature will not work properly if you have more than
one line address select in your DD program.

For details on the format of a display program, see Section 4.1 for
IIIs and Section 4.2 for Data Discs. For descriptions of the
instructions for the two display processors, see Appendix 1 and
Appendix 2.
4.4 Running Display Programs Display Output 74

PGIOT [OP=715]
--------------------------------------------------
PGIOT <function>,<argument>

The PGIOT UUO is an extended UUO that uses the AC field to determine
which of several display functions is to be executed. The individual
functions are described separately below. Of these, the PGSEL,
PGACT, and PGCLR UUOs are meaningful only for IIIs and are no-ops
when given on Data Discs.

PGSEL [OP=715, AC=0] PGIOT 0,
--------------------------------------------------
PGSEL <piece of glass number>

The PGSEL UUO causes the piece of glass whose number is the effective
address of the UUO to be selected. This means that the UPGMVM and
UPGMVE UUOs (see page 75) will refer to this piece of glass until
the next PGSEL is given.

PGACT [OP=715, AC=1] PGIOT 1,
--------------------------------------------------
PGACT <piece of glass activation map>

The PGACT UUO is used to select which pieces of glass are to be
displayed. The effective address of this UUO is interpreted as a bit
map; a one in bit 18+P will cause piece of glass number P to be
displayed, and a zero will cause that piece of glass to be invisible.

PGCLR [OP=715, AC=2] PGIOT 2,
--------------------------------------------------
PGCLR

The PGCLR UUO causes all of your pieces of glass to be cleared. This
means that the system free storage that was allocated for these PGs
is freed and whatever was displayed by them disappears never to be
seen again. This UUO does not affect your page printer at all.
4.4 Running Display Programs Display Output 75

DDUPG [OP=715, AC=3] PGIOT 3,
--------------------------------------------------
DDUPG ADR

ADR: <flags>,,<address of display program>
<length of display program in words>
<transfer-in-progress flag, if bit 0 in ADR is on>
<address of low order line command, if bit 1 in ADR is on>

The DDUPG UUO causes a user's Data Disc display program to be run.
This UUO works just like UPGIOT except that the program is always run
on the Data Disc display processor. See the UPGIOT UUO on page 72
for an explanation of the various options.

PGINFO [OP=715, AC=4] PGIOT 4,
--------------------------------------------------
PGIOT ADR

ADR: <block 21 words long for returned information>

The PGINFO UUO returns a 21 word table of information about your
pieces of glass. The effective address of the instruction should
specify the location of a 21 word block where the table is to be
stored. The information returned in the table is indicated below.

WORDS VALUE

0 <POG activation bits>,,<PP activation bits>
These are in PGACT and PPACT formats respectively; see
these two UUOs.

1:20 <word count>,,<starting address>
There is one word here for each piece of glass.

UPGMVM [OP=714]
--------------------------------------------------
UPGMVM AC,ADR

The UPGMVM UUO is used to update a III display program. Before you
give this UUO, you must have selected some piece of glass with the
PGSEL UUO. This UUO is then used to update the display program of
4.4 Running Display Programs Display Output 76

that piece of glass by replacing the word that would have been at ADR
in that program with the word in the specified AC. In other words,
you could update your display program by doing a MOVEM AC,ADR and
then another UPGIOT, or you can give this UUO with the same AC and
ADR specified. This causes a change to one word of your display
program, which is already running (unless deactivated by a PGACT
UUO). The address ADR must be within the bounds of the core area
that contained the display program when you created this piece of
glass with the UPGIOT UUO.

UPGMVE [OP=713]
--------------------------------------------------
UPGMVE AC,ADR

The UPGMVE UUO is the MOVE analog of the UPGMVM UUO described above.
This UUO picks up a word from the currently selected display program
and returns it in the specified AC.

DPYCLR [OP=701]
--------------------------------------------------
DPYCLR

The DPYCLR UUO resets your display to its initial state. Any display
programs running are cleared and the page printer is returned to its
normal condition. On a III, this means that all pieces of glass will
disappear. On a Data Disc, however, nothing is erased except that
which is overwritten by the newly redrawn page printer. The RESET
UUO (see page 139) simulates a DPYCLR. If you are not on a display,
this UUO has no effect.

4.5 Extra Data Disc Channels

The DDCHAN UUO is provided to allow users to acquire extra Data Disc
channels for use in displaying text and graphics.
4.5 Extra Data Disc Channels Display Output 77

DDCHAN [OP=047, ADR=400067] CALLI 400067
--------------------------------------------------
MOVE AC,[<channel request>]
DDCHAN AC,
<error return - for get channel and set status only>

The DDCHAN UUO is used to get and release DD channels and to get and
set the status of DD channels. This UUO should be given with a
channel request in the specified AC; this request is interpreted as
follows.

BITS OCTAL MEANINGS OF BITS IN A DATA DISC CHANNEL
REQUEST

28:29 0,,300 Operation.
0 = release channel 2 = get status
1 = get channel 3 = set status
A GET CHANNEL will fail if the requested
channel is unavailable. A SET STATUS
will fail if the channel doesn't belong
to you. These two commands skip on
success; otherwise, the direct return is
taken.

30:35 0,,77 Channel number. Values 0 through 37
specify a particular DD channel. In a
GET CHANNEL request, the value 77
specifies ANY CHANNEL. In a GET STATUS
or SET STATUS, 77 means your main
channel. In a RELEASE CHANNEL, 77
releases all channels assigned to the
job. Other values for the channel
number are undefined.

0 400000,,0 Privacy flag. A one in this bit means
no one else can look at this channel.

1 200000,,0 Write permission. A one in this bit
means that other jobs may write on this
channel.

After execution of this UUO (except for a RELEASE ALL CHANNELS or a
GET ANY CHANNEL failure), the AC contains the channel number in the
right half, the privacy and write permission status in bits 0 and 1,
plus the CHANNEL USE in bits 10:17 (377,,0 bits). A value of zero in
this use field means the channel is free; 1 through 77 mean that it
is an extra channel belonging to that job number; 100 through 177
mean that it is the main channel for the TTY line whose number is 52
4.5 Extra Data Disc Channels Display Output 78

less than this number; 200 through 377 are for special channels, such
as the one used by the system to advertise free DD terminals.

The RESET UUO (see page 139) releases all of your extra DD channels.

EXAMPLE: To request a private channel that only your job can write
on.

MOVE AC,[400000,,177]
DDCHAN AC,
JRST LOSE
WIN: ...

If you get to WIN, the channel number will be in the right half of AC
and the left half will have the sign bit on with your job number in
bits 10:17.

4.6 The Video Switch

The Video Switch is the device that determines which pictures will
appear on which TV monitors (Data Disc displays). Available to these
displays are =32 Data Disc (DD) channels, numbered 0 to 37 octal, a
null channel, and 7 television channels, numbered 41 to 47.

Each TV monitor is controlled by a 36-bit map that specifies which
channels are connected to that monitor. This map is explained below.

BITS OCTAL MEANINGS OF BITS IN A DATA DISC DISPLAY MAP

0:31 777777,,777760 DD channels. A one in bit N means that
DD channel N is connected to this
monitor.

33:35 0,,7 TV channel. Zero in this field selects
the null channel; 1 through 7 select the
corresponding TV camera, receiver, or
synthesizer. In terms of keyboard
commands, these are channels 41 through
47.

32 0,,10 Asynchronous flag. A zero in this bit
causes DD sync to be inserted; a one
blocks DD sync and all DD channels.
Whenever bits 33:35 specify an
asynchronous source, the system
automatically sets this bit to one.
4.6 The Video Switch Display Output 79

EXAMPLE: A map containing "200000,,7" selects DD channel 1 and TV
channel 47.

The system keeps two maps for each TV monitor; these maps are called
the permanent map and the temporary map. The video switch is set to
the permanent map whenever a RESET (CALLI 0) is performed.

The following UUO has been added to permit user programs to set the
maps for particular TV monitors.

VDSMAP [OP=047, ADR=400070] CALLI 400070
--------------------------------------------------
MOVE AC,[<switch request>,,ADR]
VDSMAP AC,
<error return for all operations except "get map">

ADR: <DD channel map>

The VDSMAP UUO is used to select the channels that are displayed on a
given TV monitor or to find out which channels are currently being
displayed. The right half of the AC should point to a channel map,
as described above; the meaning of the <switch request> in the left
half is explained below. If you specify a TTY line that is not a TV
monitor, then -1 is returned in the AC. Otherwise, the new map for
the indicated monitor is returned in AC.
4.6 The Video Switch Display Output 80

BITS OCTAL MEANINGS OF BITS IN A VIDEO SWITCH
REQUEST

11:17 177,,0 TTY line number of the DD display to be
switched. Zero means your own TTY line.
Other lines associated with TV monitors
(26 through 117) may be switched only if
they have no job logged in.

9 400,,0 Shadow line map. If this bit is on,
then the UUO will refer to one of the
six unused TV lines rather than to a
normal TV monitor. The number in bits
11:17 should be in the range 0:5 and
specifies which one of these six lines
is to be mapped or examined.

0 400000,,0 Temporary/permanent flag. Zero means
make a temporary change; one means make
a permanent change.

6:8 7000,,0 Operation.
0 = Get map. The current channel map
of the indicated line is returned
in the AC, and the direct return
(no skip) is always taken.
1 = Set channel map from word at ADR.
This operation skips if it is
entirely successful.
2 = Add specified channels. Bits 0:31
of the map at ADR are "or"ed into
the current map. If bits 33:35 of
the map at ADR are not all zero,
they replace the corresponding bits
in the current map. This operation
skips on complete success.
3 = Delete channels (inverse of 2).
The complements of bits 0:31 are
"and"ed with the old map. If bits
33:35 in the new map are not all
zero, this field is cleared to
zero, which selects the null TV
channel. This operation can fail
only on a busy line number. It
skips on success.
4 = Reset map. In temporary mode (per
bit 0), reset the map to the
permanent one. In permanent mode,
4.6 The Video Switch Display Output 81

reset the map to the main channel
alone. This operation can fail
only on a busy line number. It
skips on success.
5:7= Undefined.

An attempt to map someone else's private channel to any display will
fail. However, each channel being mapped is considered separately,
and a mapping operation may successfully map some channels while
failing on others. If the mapping operation fails on at least one
channel, then the UUO will take the error return. Also, unless you
are privileged, you cannot change the map of someone else's display.
A job running on a PTY can change the map of the display of the job
owning the PTY (possibly through a chain of PTYs).

EXAMPLE: To temporarily connect DD channel 21 and TV channel 47 to
your monitor.
MOVE AC,[1000,,[1,,7]]
VDSMAP AC,
JRST LOSE
WIN: ...

EXAMPLE: To get the current channel map of TTY line 37.
MOVSI AC,37
VDSMAP AC,
...

The channel map would be returned in AC.

4.7 The Audio Switch

Associated with each display is an audio speaker which can be
connected to any one of several sound sources. The ADSMAP UUO (see
below) is used to choose the sound source to be heard over the
speaker at a program's attached terminal. The BEEP UUO is used to
send a short beep to any display's speaker.
4.7 The Audio Switch Display Output 82

Each sound source that can be connected to a display's speaker is
assigned an audio channel number. The current assignments of
channels to sources is as follows:

CHANNEL SOUND SOURCE

0 Laboratory personnel paging system.
1 Lounge TV audio.
2 Tuner in Helliwell's office.
3 Tuner in computer room.
4 AD D-to-A output converter, channel 1.
5 A continuous beeping--used by the BEEP UUO.
6:17 Unconnected.

To connect a speaker to a sound source, the user specifies the
source's channel number. A speaker cannot be connected to more than
one source.

Each display has both a PERMANENT audio switch connection and a
TEMPORARY connection. When a temporary connection is made, its
duration (possibly infinite) must be specified; when the duration
runs out, the permanent connection is reselected automatically. A
RESET (see page 139) will also reselect the permanent connection.

The system allows a user to send a beep to a display terminal in
order to attract the attention of that display's user. Since a beep
may interrupt something a user is listening to, the user is permitted
to inhibit beeping on his display's speaker. Furthermore, the
personnel paging system of the laboratory uses the audio switch to
make paging announcements over users' speakers, and these pages may
also interrupt a user's selected sound source. Thus the following
system has been implemented to allow each user to decide what will
interrupt his audio switch connections.

Four possible dispositions are allowed for handling audio
interruptions; for each connection, one of these is selected for
paging interruptions and one for beep interruptions:

INTERRUPT
DON'T INTERRUPT
INTERRUPT WITH EXTENDED DURATION
DELAY BEEP

INTERRUPT means that if an interruption comes along, the connection
will be momentarily changed until the beep or page ends.

DON'T INTERRUPT means ignore all interruptions; no change will be
made even momentarily to the audio switch connection.
4.7 The Audio Switch Display Output 83

INTERRUPT WITH EXTENDED DURATION means allow interruptions to take
place but extend the duration of the connection. This is meaningful
only for temporary connections.

DELAY BEEP means postpone any beep interruption until the expiration
of the connection. This again applies only to temporary connections,
and further is not a defined disposition for paging interruptions.

ADSMAP [OP=047, ADR=400110] CALLI 400110
--------------------------------------------------
MOVE AC,[<audio switch connection>]
ADSMAP AC,

The ADSMAP UUO is used to connect a specific sound source to a
display's speaker or to find out the status of a display's audio
switch connection. The job giving this UUO must be attached to a
display terminal for this UUO to do anything; also it is not possible
for a job to affect the audio switch connection for any display but
its own.

If AC contains -1, the audio switch connection is reset to the
current permanent connection. Otherwise, the value in AC specifies
either the temporary or permanent connection and indicates whether
that connection is to be changed or just its status returned. If a
temporary connection is to be made, the duration of the new temporary
connection must be given in the right half of the AC; this duration
is in units of 1/4 second. The various fields of AC are interpreted
as follows:
4.7 The Audio Switch Display Output 84

BITS OCTAL MEANINGS OF AUDIO SWITCH CONNECTION
FIELDS

0 400000,,0 Temporary/permanent flag. A 0 in this
bit specifies the permanent audio switch
connection; a 1 means the temporary
connection.

1 200000,,0 Set/get flag. If this bit is 0, the
connection indicated by bit 0 will not
be changed; the connection status will
simply be returned in AC (with bit 0
unchanged, bits 1:4 zero, bits 5:17
containing the data indicated below, and
bits 18:35 containing the time remaining
in any temporary connection's duration,
or 0 for infinite, even if getting
permanent connection status). A 1 in
this bit means the connection is to be
changed.

2:3 140000,,0 Action taken if there is a current
temporary connection (applies only if
setting new connection):
0 Wait for any existing finite
temporary connection to expire. An
infinite temporary connection in
progress will be flushed.
1 If making a temporary connection and
there is already a finite temporary
connection, don't change the
connection; if there is an infinite
temporary connection, it is flushed
and the new connection is made. If
making a permanent connection, same
as 2 below.
2 Make this connection now regardless
of former status. Any current
temporary connection is flushed
immediately.
3 Same as 2.

4 20000,,0 Return-immediately flag. If this bit is
0 and a finite temporary connection is
to be made, the UUO will not return
until the new connection expires. A 1
in this bit makes the UUO return
immediately, possibly after waiting for
4.7 The Audio Switch Display Output 85

an old temporary connection to
expire--see bits 2:3 above.

5:6 14000,,0 Paging disposition (bit 5 is ignored for
a permanent connection):
0 Interrupt.
1 Don't interrupt.
2 Interrupt and extend duration (only
for temporary connection).

7:8 3000,,0 Beep disposition (bit 7 is ignored for a
permanent connection):
0 Interrupt.
1 Don't interrupt.
2 Interrupt and extend duration (only
for temporary connection).
3 Delay beep (only for temporary
connection).

14:17 17,,0 Audio switch channel.

18:35 0,,777777 Duration in 1/4 second units, or 0 for
infinite (temporary connections only).

9:13 760,,0 The original contents of this field are
ignored, but if bit 1 is 0 (getting
status), these bits are used to return
the following status information:

9 400,,0 Temporary connection active. This bit
will be a 1 if you have a current
temporary connection. This bit is
returned whether you are getting the
status of a temporary connection or of a
permanent connection. If you are
getting the temporary connection status
and this bit is returned as 0 (no
temporary connection), then only bits
9:12 (740,,0 bits) will return
significant data.
4.7 The Audio Switch Display Output 86

10 200,,0 Page in progress. This bit will be 1
whenever a paging announcement is being
made, whether or not your display is
allowing page interruptions.

11 100,,0 Paging interruption in progress. This
bit will be 1 whenever a paging
announcement is in progress and you are
enabled for page interruptions.

12 40,,0 Beep interruption in progress. This bit
will be 1 whenever a beep is happening
on your display.

13 20,,0 Delayed beep pending. This bit will be
1 if you have selected the delayed beep
disposition and there is a beep
interruption waiting for the expiration
of your temporary selection.

BEEP [OP=047, ADR=400111] CALLI 400111
--------------------------------------------------
MOVE AC,[<TTY line number, or -1 for self>]
BEEP AC,

The BEEP UUO causes a beep interruption for a specific display
terminal. The AC should contain the display's line number, or -1 to
beep your own display. The beep may happen at once, be delayed, or
be ignored altogether, depending on the recipient's audio switch
connection status. This UUO returns at once in any case, giving no
indication of what happened.

If the terminal being beeped is not a display, a control-G (bell) is
sent to the terminal instead of the beep.
5. Upper Segments Upper Segments 87

SECTION 5

UPPER SEGMENTS

Programs may be split into two discontiguous parts. The first part
goes from user address zero to an address called the job's protection
constant. This address, whose low order 10 bits are always 1777, is
contained in the word at JOBREL in the job data area (see Appendix
4). The second part, if it exists, starts at user address 400000
and goes up to the program's second protection constant, which is
kept in the right half of JOBHRL in the job data area. This second
part of a program, when it exists, is called the UPPER SEGMENT,
SECOND SEGMENT or HIGH SEGMENT of that job. The first part is
usually called the LOWER SEGMENT and is the controlling job. An
upper segment cannot execute code except when attached to a lower
segment.

An upper segment can be shared by several jobs; this saves core by
eliminating all but one copy of the same piece of code. However, it
uses up an extra job slot because each upper segment is given a
separate job number.

Since upper segments are sometimes shared, they can be write
protected to prevent any job from changing the code and/or data in a
segment, which, after all, may be part of another job. Write
protection is just an option, however, and shared segments are not
required to be protected. The SETUWP UUO is used to change an upper
segment's write protection status. The sign bit of JOBHRL will be on
when your upper segment is write protected.

Another use of upper segments involves having several of them which
are attached by a lower segment one at a time and detached when the
next one is needed. For a job to be run, it must be entirely in
core, including its attached upper segment, if any.

Upper segments have a protection scheme similar to that used on the
disk. Each upper segment has a nine bit protection key which
indicates who may use that segment and how they may use it. The nine
bits are in three groups of three bits each. The first group tells
what the creator PPN may do with the segment, the second group tells
what others with the same project as the creator may do, and the
third group tells what anyone else may do. Within each group, the
first bit is unused, the second bit is read protection and the third
bit is status change protection. Read protection prevents you from
attaching to the segment; status change protection prevents you from
changing the name, write protection status, core size, or protection
of the segment.
5.1 Making and Killing Segments Upper Segments 88

5.1 Making and Killing Segments

There are three ways you can become attached to an upper segment.
You can run an SSAVEd program (i.e., one that was saved with its
upper segment), in which case you will get the segment that was
attached to the program when it was saved; or you can attach to an
already existing upper segment; or you can create a new upper
segment.

Every job, including upper segments, has a list of credentials.
These include the job name, the project-programmer name of the source
dump file of the current program, the physical and logical names of
the device the dump file was on, the creation date of the dump file
and the protection. The protection for a lower segment will always
be 000 unless it has been changed by the SETCRD UUO (see page 99),
which can also be used to set the protection and creation date for an
upper segment. When you cause a new upper segment to be created, its
credentials are copied from your job. For a given job, all of the
credentials except the protection are set from their values for the
dump file which holds the current program. If the dump file was
SSAVEd, then the upper segment will be initialized to the same
protection it had when it was saved. The lower segment is set up
with protection 000.

Let me explain this a bit further with some examples. If you run a
system program, your job name will be the file name of the dump file
on [1,3], your job PPN (not to be confused with your logged-in PPN)
will be 1,3, your job physical device name will be DSK, your logical
device name will probably be null, and your job creation date will be
the creation date of the dump file. If you run a user program from,
say, the disk area [ABC,DEF], then all this stuff will be the same
except that your job PPN will be ABC,DEF.

The LINKUP UUO is used to search the system for an upper segment with
credentials that match those of your job. The SETPRO UUO (see page
92) can be used to set an upper segment's protection. The SETCRD
UUO (see page 99) can be used to set the creation date and
protection either for a lower segment or for an upper segment.

When you are finished with an upper segment, you should kill it.
This means that it will go away (giving up its job number) unless
someone else is still using it.

The following UUOs are used to create, kill, attach and detach upper
segments and to change the size of an upper segment.
5.1 Making and Killing Segments Upper Segments 89

LINKUP [OP=047, ADR=400023] CALLI 400023
--------------------------------------------------
LINKUP
<error return>

The LINKUP UUO attempts to find an already existing upper segment
with the same job name, date of creation, and other credentials as
your job has. (The list of credentials required for an upper segment
to match your job is given above.) If such an upper segment is found
which is not protected from you, it is attached to your job and the
skip return is taken. If there is no such upper segment, you get the
direct (error) return. Any segment you were attached to when you
gave this UUO is killed before all this happens.

REMAP [OP=047, ADR=37] CALLI 37
--------------------------------------------------
MOVE AC,[<write-protect flag>,,<highest address in lower>]
REMAP AC,
<error return>

The REMAP UUO causes your core image to be broken into two segments.
The address contained in the AC right is taken as the address of the
last word to be in the lower segment. The next word becomes the
first word in the upper segment and its address becomes 400000. If
the sign bit of the AC is on when this UUO is given, the upper
segment will be write protected.

Before your core image is broken, an automatic LINKUP is attempted in
order to find an already existing upper segment with your
credentials; see the LINKUP UUO above. If one is found, the part of
your core image that would otherwise have become your upper segment
is discarded and your core size reduced appropriately before
attaching to the already existing upper segment.

If this UUO is successful, the skip return is taken and the job
number of your upper segment is returned in AC. If the automatic
LINKUP fails and there are no more job numbers left to create a high
segment under, or if there is something illegal in your
specifications, the direct (error) return is taken.

Any upper segment you are attached to when you give the REMAP UUO is
killed before anything else is done.
5.1 Making and Killing Segments Upper Segments 90

CORE2 [OP=047, ADR=400015] CALLI 400015
--------------------------------------------------
MOVEI AC,<highest upper segment address desired>
CORE2 AC,
<error return>

The CORE2 UUO is used to change the size of your upper segment. The
address in the AC is interpreted as the highest address you want in
your upper segment; this address, if non-zero, is ORed with 1777 and
the 400000 bit is ignored. If the AC contains zero, any upper
segment you have will be killed (unless it is protected from you, in
which case it will simply be detached from your job) and the skip
return will be taken.

If the AC contains a non-zero number and you do not have an upper
segment, an upper segment of the specified size will be created for
you. If you already have an upper segment, its size is adjusted to
that specified by the number in the AC. If this UUO is successful,
the skip return is taken. If there is not enough core to grant your
request, or if the segment is protected from you, the direct (error)
return is taken. Unless you are killing your upper segment (with a
zero in AC), this UUO returns with the AC containing the total number
of 1K blocks available to a single user program, counting both upper
and lower segments.

ATTSEG [OP=047, ADR=400016] CALLI 400016
--------------------------------------------------
MOVE AC,[<job number or name>]
ATTSEG AC,
<error return - code in AC>

The ATTSEG UUO is used to attach to an upper segment that already
exists. You must not already have an attached upper segment. The AC
should contain either the sixbit job name or the job number of the
upper segment to which you wish to attach. If this UUO is
successful, the skip return is taken. Otherwise the direct (error)
return is taken and a code is returned in the AC indicating the cause
of failure. The error codes and their meanings are explained below.
5.1 Making and Killing Segments Upper Segments 91

ERROR CODE MEANING

0 A protection violation has occurred; you are
not allowed to attach to this upper segment.

1 There are two or more upper segments with the
job name you gave. The job number of the first
one is returned in the left half of AC.

2 The job number you gave is not the job number
of an upper segment.

3 There is no job with the name you gave.

4 You already have an upper segment.

DETSEG [OP=047, ADR=400017] CALLI 400017
--------------------------------------------------
DETSEG <flag>,

The DETSEG UUO detaches your upper segment from your job. Normally
your upper segment is placed into a list of the segments you have
detached, so that when you do a RESET (see page 139), all your
detached segments will go away. However, if the low order bit of the
AC field is a one, then the segment will not go into the list, but
will stick around like any other detached job. This is not
recommended because it can result in the proliferation of unused
upper segments. Only the low order bit of the AC field is looked at
by this UUO.

If you have a simulated upper segment (see the SETPR2 UUO on page
103), it is killed by this UUO.

5.2 Getting/Setting Segment Status

The following UUOs are used to find out and/or change the protection,
name and other information associated with an upper segment.
5.2 Getting/Setting Segment Status Upper Segments 92

SETUWP [OP=047, ADR=36] CALLI 36
--------------------------------------------------
MOVEI AC,<zero for unprotect, non-zero for protect>
SETUWP AC,
<protection violation return>

The SETUWP UUO is used to write protect or unprotect your attached
upper segment. If AC contains zero, the segment becomes unprotected;
otherwise it becomes protected. If this UUO is successful, the skip
return is taken. If the segment is protected from you, then you get
the direct (error) return. If you have no upper segment, you always
get the skip (success) return. The sign bit of JOBHRL in the job
data area is a one if your upper segment is write protected.

UNPURE [OP=047, ADR=400102] CALLI 400102
--------------------------------------------------
UNPURE
<error return>

The UNPURE UUO is used to unprotect your upper segment. If you are
sharing a write-protected upper segment with other users, this UUO
will create an unprotected copy of that upper segment (assigning it a
new job number), detach you from the old segment and attach you to
this new segment. If you are the sole user of a write-protected
upper segment, this UUO will simply unprotect that segment. The skip
return will be taken upon success, at which time your upper segment
will not be write protected. If there are no job numbers available
for a copy of your upper segment, or if you cannot be granted enough
core, the direct (error) return will be taken. If you have no upper
segment, or if your upper segment is not write protected, you always
get the skip (success) return.

SETPRO [OP=047, ADR=400020] CALLI 400020
--------------------------------------------------
MOVE AC,[<Bits 0:8 = new prot key; bits 30:35 = job no.>]
SETPRO AC,
<error return>

The SETPRO UUO can be used to change the protection key of any upper
segment not protected from you. Bits 30:35 (0,,77 bits) in the AC
should contain the job number of the upper segment whose protection
you wish to change, where zero means your own attached upper segment;
5.2 Getting/Setting Segment Status Upper Segments 93

bits 0:8 of the AC should contain the new protection key you wish the
segment to have. If this UUO is successful, the skip return is
taken. If a protection violation occurs or if the job indicated is
not an upper segment, the direct (error) return is taken.

SETNM2 [OP=047, ADR=400036] CALLI 400036
--------------------------------------------------
MOVE AC,[<sixbit name for your upper segment>]
SETNM2 AC,
<error return>

The SETNM2 UUO is used to change the job name of your upper segment.
The name you wish your segment to have should be in the AC when you
give this UUO. If your segment is successfully renamed, the monitor
then scans the names of other upper segments in the system, and if
there is one with the same name as yours, its job number is returned
in the AC; if there is no other upper segment with the same name,
zero is returned in the AC. The skip return is taken on success. If
you are not permitted to change your upper segment's name, the direct
(error) return is taken. If you have no segment attached, the skip
(success) return is always taken.

POINTS [OP=712]
--------------------------------------------------
POINTS ADR

ADR: <block =63 words long for returned job numbers>

The POINTS UUO returns a list of the job numbers of all jobs,
including your own, which are attached to your upper segment. This
list is returned in the block pointed to by the effective address of
the UUO, with one job number per word. The end of the list is
indicated by a zero. This list can be up to =63 words long.

SEGNAM [OP=047, ADR=400037] CALLI 400037
--------------------------------------------------
SEGNAM AC,

The SEGNAM UUO returns in AC the sixbit job name of your upper
segment. If you have no upper segment attached, zero is returned.
5.2 Getting/Setting Segment Status Upper Segments 94

SEGNUM [OP=047, ADR=400021] CALLI 400021
--------------------------------------------------
MOVEI AC,<job number>
SEGNUM AC,

The SEGNUM UUO gets the job number of the upper segment attached to
the job whose number is in AC. The segment number is returned in AC.
A zero in AC gets your own segment number. A zero returned means the
specified job has no upper segment attached.
6. Information Information 95

SECTION 6

GETTING/SETTING INFORMATION

This section describes numerous UUOs that allow you to get certain
types of information from the system and to change some of this
information regarding your job.

6.1 Dates and Times

Here are some UUOs to get various flavors of date and time.

DATE [OP=047, ADR=14] CALLI 14
--------------------------------------------------
DATE AC,

The DATE UUO returns in AC the current date in system date format.
The number returned has the following value:
((year-1964)*12+month-1)*31+day-1, where all these numbers are in
decimal. You can calculate the day, month and year by dividing. If
you divide by =31, the remainder is then day-1. Then if you divide
the quotient by =12, the new remainder is month-1. Finally, if you
take the quotient again and add =1964, you get the year.

DAYCNT [OP=047, ADR=400100] CALLI 400100
--------------------------------------------------
MOVE AC,[<date in system date format>]
DAYCNT AC,

The DAYCNT UUO converts a date from system date format (see the DATE
UUO above) to the number of days from 1 January 1964 to the date
indicated. AC should contain the date of interest, where zero or a
negative number is taken to mean today's date. The corresponding day
count is returned in AC.
6.1 Dates and Times Information 96

TIMER [OP=047, ADR=22] CALLI 22
--------------------------------------------------
TIMER AC,

The TIMER UUO returns in AC the time of day in 60ths of a second
after midnight.

MSTIME [OP=047, ADR=23] CALLI 23
--------------------------------------------------
MSTIME AC,

The MSTIME UUO returns in AC the time of day in milliseconds after
midnight. This time is accurate only to the nearest 60th of a
second.

ACCTIM [OP=047, ADR=400101] CALLI 400101
--------------------------------------------------
ACCTIM AC,

The ACCTIM UUO returns the current date and time. The date is
returned in the left half of AC and is in system date format (see the
DATE UUO above). The time is returned in the right half of AC and is
in seconds after midnight.

DSKTIM [OP=047, ADR=400072] CALLI 400072
--------------------------------------------------
DSKTIM AC,

The DSKTIM UUO returns in AC the current date and time in file
time/date written format: bits 13:23 (37,,770000 bits) hold the time
in minutes after midnight, and bits 24:35 (0,,7777 bits) hold the
date in system date format (see the DATE UUO above).
6.1 Dates and Times Information 97

RUNTIM [OP=047, ADR=27] CALLI 27
--------------------------------------------------
MOVE AC,[<job number>]
RUNTIM AC,

The RUNTIM UUO returns in AC the total compute time since login used
by the job whose number is in the AC. A zero job number in the AC
will get the compute time for your own job. The time returned is in
milliseconds although it is kept by the system in 60ths of a second
and is not even exact to that accuracy. An illegal job number
specified will cause zero to be returned.

6.2 Job Information

Here are some UUOs to find out things about specific jobs and even to
set certain values for your own job.

CORE [OP=047, ADR=11] CALLI 11
--------------------------------------------------
MOVEI AC,<highest address you want in your lower segment>
CORE AC,
<error return>

The CORE UUO is used to change your core size (the size of your lower
segment if you have a two segment program). AC should contain the
highest address (in your lower segment) that you want to be able to
reference. This address, if non-zero, is ORed with 1777 (to make it
a 1K boundary), and then your core size is adjusted, if necessary, to
the size indicated. If you can be given the amount of core you
request, the skip return is taken; if not, the direct (error) return
is taken. In any case, the maximum number of 1K blocks a single
program is allowed to use, counting both upper and lower segments, is
returned in the AC. If the AC originally contains zero, then no
change is made in your core size, but the number of 1K blocks
available to a single program is returned in the AC and the direct
(error) return is taken.
6.2 Job Information Information 98

PJOB [OP=047, ADR=30] CALLI 30
--------------------------------------------------
PJOB AC,

The PJOB UUO returns your job number in the AC.

GETPPN [OP=047, ADR=24] CALLI 24
--------------------------------------------------
GETPPN AC,

The GETPPN UUO returns in AC the logged-in project-programmer name of
your job.

GETNAM [OP=047, ADR=400062] CALLI 400062
--------------------------------------------------
MOVEI AC,<job number>
GETNAM AC,

The GETNAM UUO is used to get the name of any job on the system. AC
should contain the number of the job whose name you wish to know. If
AC contains zero, a negative number, or an illegal job number, then
your job is assumed. The sixbit name of the job specified is
returned in AC.

SETNAM [OP=047, ADR=43] CALLI 43
--------------------------------------------------
MOVE AC,[<sixbit job name>]
SETNAM AC,

The SETNAM UUO is used to change your job name to that given in the
AC. Any job name is legal.
6.2 Job Information Information 99

SETCRD [OP=047, ADR=400073] CALLI 400073
--------------------------------------------------
MOVE AC,[<new protection and creation date>]
SETCRD AC,

The SETCRD UUO is used to set the protection and creation date of
either your lower segment or your upper segment. The new protection
and creation date are taken from the AC specified in the UUO. If any
of bits 0, 3 and 6 (444000,,0 bits) are ones, the protection and
creation date of your upper segment are set; otherwise the protection
and creation date of your lower are set. Bits 0:8 specify the
protection, bits 13:23 the time of creation (in minutes after
midnight) and bits 24:35 the date of creation (in system date
format). Bits 0, 3 and 6 (444000,,0 bits) are turned off before the
protection is stored. If bits 13:35 are all zero, the current time
and date will be used. The protection and creation date are used
mainly in conjunction with linking to or creating an upper segment;
see Section 5 on upper segments.

SETPRV [OP=047, ADR=400066] CALLI 400066
--------------------------------------------------
MOVE AC,<privilege bits you want>
SETPRV AC,

The SETPRV UUO is used to find out and/or change your privileges. AC
should contain either -1 or the privilege bits you want. If AC
contains -1, then your privileges will not be changed. Otherwise, an
attempt will be made to set your privilege bits to those indicated in
AC. New privilege bits will be granted only if either 1) you
currently have the privilege privilege (bit 0--the 400000,,0 bit
represents the privilege privilege) or 2) JBTSTS indicates that you
are an accounting program with JACCT set. However, the system will
be glad to turn off the bits for any privileges you wish to
surrender. Under any circumstances, the resultant settings of your
privilege bits will be returned in AC. For the meanings of the
various privilege bits, or to request privileges, see any system
programmer.
6.2 Job Information Information 100

SLEVEL [OP=047, ADR=400044] CALLI 400044
--------------------------------------------------
MOVEI AC,<job number>
SLEVEL AC,

The SLEVEL UUO is used to find out a job's current service level. AC
should contain the number of the job whose service level you want to
know; a zero job number means your own job. The service level (in
percent) of the job indicated will be returned in the left half of
AC; the right half will contain the job number. If you specify an
illegal job number, zero will be returned in AC.

RLEVEL [OP=047, ADR=400054] CALLI 400054
--------------------------------------------------
MOVEI AC,<programmer name>
RLEVEL AC,

The RLEVEL UUO is used to find out how much service level is reserved
for the current hour by a particular programmer name. The programmer
name should be in the right half of AC; the service level (in
percent) is returned in the left half of AC. The right half of AC is
unchanged by this UUO unless the reserved service level is zero, in
which case zero is returned in the whole AC. The original value of
AC left is ignored by this UUO.

6.3 Looking at the Monitor

Here are some UUOs used to examine various parts of the monitor.

NAMEIN [OP=047, ADR=400043] CALLI 400043
--------------------------------------------------
MOVE AC,[<sixbit job name>]
NAMEIN AC,
<error return - code in AC>

The NAMEIN UUO is used to determine if there are any jobs in the
system with a particular job name. AC should contain the job name
you are interested in. If there is exactly one job with the given
name, the skip (success) return is taken and the job number of the
6.3 Looking at the Monitor Information 101

job with that name is returned in the AC. Otherwise, the direct
(error) return is taken and a code is returned in AC; a code of 1
means that there is no job with the given name, and a code of 3 means
that there are two or more jobs with that name.

JBTSTS [OP=047, ADR=400013] CALLI 400013
--------------------------------------------------
MOVEI AC,<job number>
JBTSTS AC,

The JBTSTS UUO is used to get from the system the job status word for
a particular job. AC should contain the number of the job of
interest, where zero means your own job. The table below gives the
meanings of some of the bits in this word.

BITS OCTAL NAME MEANINGS OF 1'S IN THE JOB
STATUS WORD

0 400000,,0 RUN The job is runnable, though it
may be in a wait state of some
kind. This bit gets turned
off by typing control-C,
giving the EXIT UUO, or
hitting some kind of error.

1 200000,,0 CMWB The job is waiting to be
swapped in to service a
monitor command.

2 100000,,0 JACCT LOGIN or LOGOUT is running;
control-C cannot be typed at
this time.

3 40000,,0 JNA A job number has been assigned
to this job.

4 20000,,0 JERR The job has hit an error and
cannot be continued.

5 10000,,0 JLOG The job is successfully logged
in. System phantom jobs (see
the WAKEME UUO on page 146)
run with this bit off as do
temporary jobs
(project-programmer name of
100,100) started up by monitor
6.3 Looking at the Monitor Information 102

commands (like WHO) that need
a job but which do not require
you to be logged in. A job
with the JLOG bit off will go
away if it hits an error (such
as a parity error or illegal
memory reference) or if a
monitor command is typed to
it.

6 4000,,0 SHF The job is currently being
shuffled in core.

7 2000,,0 SWP The job is swapped out.

8 1000,,0 JSEG The job is really an upper
segment.

17 1,,0 JWP This upper segment is write
protected. This bit is
meaningful only if bit 8 is
on, that is, only if this job
is an upper segment.

20 0,,100000 JLOCK The job is locked in core by
the LOCK UUO; see page 147.

23 0,,10000 FBINP The job has a fast band
transfer in progress. See
Section 10.

24 0,,4000 FBERP The job had an error on the
last fast band transfer. See
Section 10.

30:35 0,,77 Job number of this job's upper
segment, if any; this field is
zero if the job has no upper.

SWITCH [OP=047, ADR=20] CALLI 20
--------------------------------------------------
SWITCH AC,

The SWITCH UUO returns in AC the current setting of the PDP-10
console data switches.
6.3 Looking at the Monitor Information 103

CALLIT [OP=047, ADR=400074] CALLI 400074
--------------------------------------------------
MOVE AC,[<opcode, CALLI number or UUO mnemonic>]
CALLIT AC,

The CALLIT UUO is used to find out the opcode corresponding to a
given UUO mnemonic or to find out the mnemonic for an opcode or CALLI
number. AC should contain the opcode, CALLI number or sixbit
mnemonic of the UUO you are interested in. The result is returned in
AC: for UUO mnemonics, the opcode is returned (i.e., a full 36-bit
instruction including relevant AC or address fields); for opcodes the
most specific sixbit mnemonic is returned (e.g., opcode 051000,,0
returns 'INCHRW' and 051040,,0 returns 'OUTCHR'), unless bit 17 (1,,0
bit) was on originally in the AC, in which case the generic mnemonic
is returned (e.g., opcode 051001,,0 returns 'TTYUUO'); for CALLI
numbers, the sixbit CALL name is returned (e.g., 0,,400003 returns
'SPCWGO'). If the given mnemonic, opcode or CALLI number is
undefined, zero is returned.

This UUO works by first checking bits 13:16 (36,,0 bits) in the AC.
If these bits are all zero, the argument is assumed to be an opcode;
if any of these bits is non-zero, the argument is assumed to be a
sixbit mnemonic. Thus any one- or two-character mnemonic will be
mistaken for an opcode; however all UUO mnemonics are three or more
characters. Also, all irrelevant fields in the argument must be zero
to avoid confusion.

SETPR2 [OP=047, ADR=400052] CALLI 400052
--------------------------------------------------
MOVE AC,[<prot>,,<reloc>]
SETPR2 AC,
<error return>

(Low order bit of <prot> on means write protect "upper segment;"
low order bit of <reloc> on means <reloc> is in relative mode.)

The SETPR2 UUO sets your second protection/relocation register in
order to simulate the possession of an upper segment. There are two
purposes for doing this: the first is to allow you to look at any
part of core, particularly at the monitor, efficiently; the second
purpose is to enable your job to address part of your core image as
if it were in an upper segment (addresses over 400000) even though it
isn't. The table in Appendix 5 tells where in the monitor you can
find various interesting pieces of system information which you can
access by using this UUO.
6.3 Looking at the Monitor Information 104

NOTE: Any attached upper segment (real or simulated) that you have
will be killed when you give this UUO. See Section 5 on upper
segments. Also, both the RESET UUO (see page 139) and the DETSEG UUO
(see page 91) undo the effect of SETPR2.

At the time this UUO is called, AC right should contain the
relocation you wish to simulate and AC left should contain the
protection you wish to simulate as an upper segment. Furthermore, if
the low order bit of AC left (bit 17--the 1,,0 bit) is on, your
"upper segment" will be write protected; and if the low order bit of
AC right (bit 35--the 0,,1 bit) is on, the relocation specified will
be assumed relative to your core image--that is, your own true
relocation constant will be added in to <reloc> before setting the
second prot/reloc register. Upon success, this UUO takes the skip
return; if your request specifications are impossible to satisfy,
then the direct (error) return is taken.

If you give an absolute <reloc> and you are not privileged, your
"upper segment" will automatically be write protected. Finally, the
system will adjust the values you specify in AC to 1K boundaries; for
<reloc> the low order =10 bits (0,,1777 bits) will be turned off, and
for <prot> the low order =10 bits (1777,,0 bits) will be turned on.
Thus, a <prot> of 4321 will be made into 5777, and a <reloc> of 3210
will be made into 2000, with all this happening after the system has
taken note of the low order bits of both AC left and AC right.

Now, if you still don't understand (and even if you do), let me
explain further. Suppose you wish to look at certain locations in
the monitor (for whatever reason). You can use this UUO once and
then do simple MOVEs (or their equivalent) to get the information you
want. For instance, if you would like to put into AC whatever is in
the system at EXEC location 220, you can execute the following
sequence of instructions.

MOVSI AC1,377777 ;<reloc> = 0, <prot> = 377777
SETPR2 AC1, ;make the first 128K of core
; into your "upper segment"
HALT ;halt on error return
...
MOVE AC,400220 ;get whatever is in EXEC 220
...

The relative mode use of this UUO allows you to write code as if it
were going to run as a second segment, and then to execute it without
making it into a second segment, provided you have used this UUO with
the relative mode bit set. You could even do overlays by reading
another piece of code, also written to run as a second segment, into
the same place. The base address of the second segment code,
however, should be on a 1K boundary or you might get confused about
what is happening.
6.3 Looking at the Monitor Information 105

GETPR2 [OP=047, ADR=400053] CALLI 400053
--------------------------------------------------
GETPR2 AC,

The GETPR2 UUO is used to fetch the protection/relocation of your
simulated upper segment. The protection is returned in the left half
of AC; bit 17 (1,,0 bit) is on if access to the segment is write
protected. The relocation is returned in the right half of AC; bit
35 (0,,1 bit) is on if the relocation is in relative mode. See
SETPR2 above for an explanation of simulated upper segments.

If you do not have a simulated second segment at the time you call
this UUO (for example, if you have a real second segment), then zero
is returned in AC.

PEEK [OP=047, ADR=33] CALLI 33
--------------------------------------------------
MOVEI AC,<absolute address you want to look at>
PEEK AC,

The PEEK UUO is used to get the contents of any absolute location in
memory. AC should contain the absolute address you wish to examine.
The contents of that address will be returned in AC. Appendix 5
tells where you can find some interesting system information in the
monitor.

This UUO has been largely replaced by the SETPR2 UUO (explained
above), which makes examining memory outside your core image much
more efficient. However, if you have an upper segment, you must
detach it to use the SETPR2 UUO but not to use the PEEK UUO.
7. Mail System Mail System 106

SECTION 7

INTER-JOB MAIL SYSTEM

The inter-job mail system provided by the monitor allows =32 word
letters to be passed between jobs. Each job in the system has a
mailbox which can hold exactly one =32 word letter. For a letter to
be sent, the sending job identifies the destination job by either the
job number or the sixbit job name. This causes the letter to be
placed in the mailbox of the destination job, who can then take the
letter out of his own mailbox (i.e., receive the letter) whenever he
wants. While a job's mailbox is full (holding a letter he hasn't
read yet), no one can send that job a letter.

NOTE: The RESET UUO (see page 139) will cause any letter in your
mailbox to be thrown away.

MAIL [OP=710]
--------------------------------------------------
MAIL <function>,ADR

The MAIL UUO is an extended UUO that uses the AC field to determine
which of several mail-handling functions is to be executed. Each of
these functions is described separately below. Notice that MAIL is
an IOT UUO and hence cannot be given by a program that is currently
in USER-IOT mode (which is explained in Appendix 3).

7.1 Sending Mail

The following two UUOs allow you to send a letter to any job.
7.1 Sending Mail Mail System 107

SEND [OP=710, AC=0] MAIL 0,
--------------------------------------------------
SEND ADR
<error return>

ADR: <destination job name or number>
<address of =32 word letter to be sent>

The SEND UUO is used to send a letter to any job in the system. The
effective address of the UUO should point to a two-word block. The
first word of this block should be the job number or the sixbit job
name of the job to which the letter is to be sent. The second word
of the block should contain the address of the =32 word letter.

If the letter is successfully sent, the skip return is taken. If the
destination job already has a letter in his mailbox (meaning the
letter cannot be sent at this time), the direct (error) return is
taken. If there is no job with the name or number you give, you get
the system error message NON-EX JOB NAME OR NUMBER. If there are two
or more jobs with the job name you give, you get the system error
message AMBIGUOUS JOB NAME. With either of these last two errors,
your program will be stopped and you will be permitted to type
CONTINUE, which will cause this UUO to be tried again.

SKPSEN [OP=710, AC=5] MAIL 5,
--------------------------------------------------
SKPSEN ADR
<return for destination mailbox full>
<return for letter successfully sent>
<return for non ex job name or number, or ambiguous name>

ADR: <job name or number>
<address of =32 word letter to be sent>

The SKPSEN UUO is used to send a letter to another job just as the
SEND UUO (see above) does except that there is an extra return, which
is taken when there is no job with the given name or number or when
there are two or more jobs with the given name. Thus, there are
three possible returns that this UUO can take. The direct return (no
skip) is taken if the letter cannot be sent because the addressee
already has a letter in his mailbox. The skip return is taken if the
letter is successfully sent. The double skip return is taken if
there is no job with the given name or number or if there are two or
more jobs with the given name.
7.2 Receiving Mail Mail System 108

7.2 Receiving Mail

The following two UUOs allow you to receive mail sent to you, that
is, to have a letter removed from your mailbox and deposited in your
core image.

WRCV [OP=710, AC=1] MAIL 1,
--------------------------------------------------
WRCV ADR

ADR: <block =32 words long to receive a letter>

The WRCV UUO takes the letter, if any, that is in your mailbox and
places it in the =32 word block specified by the effective address of
the UUO. If there is no letter in your mailbox, this UUO waits until
someone sends you one and then gives it to you.

SRCV [OP=710, AC=2] MAIL 2,
--------------------------------------------------
SRCV ADR
<return if no letter is in your mailbox>
<success return>

ADR: <block =32 words long to receive a letter>

The SRCV UUO checks to see if there is a letter in your mailbox. If
there is one, it is returned to you in the =32 word block pointed to
by the effective address (ADR) of this UUO and the skip return is
taken. If there is no letter in your mailbox, the direct return is
taken and the block at ADR is untouched.

7.3 Peeking at Mailboxes

The following two UUOs allow you to find out whether a job has a
letter in its mailbox.
7.3 Peeking at Mailboxes Mail System 109

SKPME [OP=710, AC=3] MAIL 3,
--------------------------------------------------
SKPME
<return for your mailbox empty>

The SKPME UUO tells you whether or not there is a letter in your
mailbox. If there is a letter there, the skip return is taken; if
not, the direct return is taken.

SKPHIM [OP=710, AC=4] MAIL 4,
--------------------------------------------------
SKPHIM ADR
<return for his mailbox empty>

ADR: <name or number of job you are interested in>

The SKPHIM UUO is used to find out if a given job has a letter in his
mailbox. The job number or sixbit job name of the job of interest
should be in the word pointed to by the effective address of this
UUO. If that job has a letter in his mailbox, the skip return is
taken; if his mailbox is empty, the direct return is taken. If there
is no job with the name or number given, you will get the system
error message NON-EX JOB NAME OR NUMBER. If there are two or more
jobs with the job name given, then you will get the system error
message AMBIGUOUS JOB NAME. If either of these two errors occurs,
your program will be stopped and you will be permitted to type
CONTINUE, which will cause this UUO to be tried again.
8. Spacewar Mode Spacewar Mode 110

SECTION 8

SPACEWAR MODE

In a timesharing system the available CPU time must be split up among
all the programs that are trying to run. Any one program will be run
only for a short period of time, then stopped for a while to let
other programs run, then run a little more, etc. The intervals
between, and durations of, the times when a program is allowed to run
are generally irregular and depend on the system load. Certain
programs require fairly regular service (in the form of CPU time
allocated) in order to operate meaningfully. The system provides
spacewar mode to assure regular service to such programs.

To use spacewar mode, a job tells the system the starting address of
the spacewar module (process) and how often and on which processor(s)
(PDP-10, PDP-6) it should be run. A spacewar module is a separate
process from your job's main process (the one that initiates the
spacewar module) but runs in the same core image. The spacewar
module will be restarted at a fixed interval after it last stopped;
you specify this interval when you initiate the module. A spacewar
process cannot quite be guaranteed of running every so often because,
for example, another spacewar process on the same processor could
have conflicting time demands. After you have initiated a spacewar
module, your job's main process can continue doing whatever it wants.
You are allowed to have one spacewar module active on each processor;
i.e., you can have one on the PDP-10 and another one on the PDP-6.

While you have a spacewar module active, your job usually will not be
swapped out although it may be shuffled to a different place in core.
Before your job is either shuffled or swapped out, your spacewar
module will be warned that it is not going to be run for a while; so
it can take whatever precautions are necessary to see that nothing
bad happens while it is away.

Each time a spacewar process is started up, it is allowed to run
until either it signals by the DISMIS UUO (see page 114) that it is
done or it times out. Normally a spacewar process will time out if
it runs for more that half a second during a single activation. If
you set the timeout-suppression bit (see the SPCWGO UUO below) for a
spacewar process, then that process will never time out. However,
running for very long (like more than a few milliseconds) will cause
system performance to deteriorate noticeably, especially if the
process is running on the PDP-10! In fact, a spacewar module running
on either processor for more than about half a second will cause the
other processor to think that the first processor is dead.
8. Spacewar Mode Spacewar Mode 111

If a spacewar process makes an illegal or non-existent memory
reference, or if it gets a push-down overflow, then the message
SPACEWAR LOSSAGE will be typed on the job's terminal and both the
spacewar process and the main process will be stopped. If you try to
initiate a spacewar process when one is already active, or if you
indicate that a spacewar process should be run on the PDP-6 and the
PDP-6 is not running, or if one of your spacewar processes times out,
then you will get an error message and your spacewar processes will
be killed.

Spacewar modules are started in IOT-USER mode; this means that
operation codes 700:777 are machine I/O instructions rather then
UUOs. Thus a spacewar process can do its own I/O directly; however,
it should make sure that its use of I/O devices will not conflict
with the system. For more information on IOT-USER mode, see its
description in Appendix 3.

Spacewar modules running on the PDP-6 can never do UUOs. Any attempt
by such a process to do a UUO will result in termination of that run
(as by DISMIS). Spacewar modules running on the PDP-10 are allowed
to do certain UUOs. However, a UUO that attempts to reference any
accumulators will never access the correct set of ACs (whether the AC
is referenced as an AC or as a memory location); and a UUO that
returns results in the ACs may in fact return the results in the ACs
of the job's main process (if the main process is at UUO level), thus
clobbering whatever the main process had in its AC(s)! Furthermore,
any UUO that must wait for something to happen will not work from a
spacewar module. Finally, some illegal UUOs will cause the SPACEWAR
LOSSAGE message to be printed and the spacewar modules to be killed.
With those warnings in mind, note that spacewar modules on the PDP-10
can in general do any of the IOT UUOs, that is, those with opcodes
over 700 (including the display UUOs) but not until the process gets
itself out of IOT-USER mode!! See the preceding paragraph.

Each time a spacewar process is started up, the system loads up
several accumulators with data that might be needed by the spacewar
module. The ACs set up and the data they contain are listed below.

AC CONTENTS

1 The current value of the spacewar buttons. See the
SPWBUT UUO on page 149.

2 Your current protection-relocation constant. Your
protection constant is in the left half and your
relocation constant is in the right half of this AC.

3 A warning value. This AC usually contains zero but is
set up with -1 if this is the last time your spacewar
8. Spacewar Mode Spacewar Mode 112

process will be run for a while (because your job is
being swapped out or shuffled). The next time your
spacewar module runs, this AC will contain the number
of 60ths of a second for which your spacewar module
was suspended.

4 The number of the processor this spacewar module is
running on. This number is 1 for the PDP-10 and 2 for
the PDP-6.

5 A flag indicating the status of the processor that
this spacewar process is NOT running on. This flag is
zero if that processor is running (normal state) and
-1 if that processor is dead.

6 Your job status word. See the JBTSTS UUO on page 101.
If the run bit (bit 0--the 400000,,0 bit) of this word
is zero, then your main process has stopped for some
reason; for instance, control-C may have been typed.

If you initiate a spacewar process with the time between runs set to
zero, then the process will be run only once.

Whenever you do a RESET (see page 139), any spacewar modules active
will be killed. The EXIT UUO (see page 138) will also kill any
spacewar modules you have. Finally, the SPCWAR UUO can also be used
to kill your spacewar modules; see below.

8.1 Spacewar UUOs

Here are the UUOs used to initiate and to kill spacewar processes and
to terminate spacewar activations.

SPCWAR [OP=043]
--------------------------------------------------
SPCWAR <number of ticks between startups>,<starting address>

The SPCWAR UUO initiates a spacewar process on the PDP-6. If the
PDP-6 is not running, the spacewar process will be run on the PDP-10
instead. The effective address of the UUO is the process' starting
address. The number of 60ths of a second between startups is
specified by the AC field of the instruction (possible values of
0:17). If the AC field is zero, then the spacewar process will be
8.1 Spacewar UUOs Spacewar Mode 113

run only once. Timeout suppression is not possible with the SPCWAR
UUO; any process started with this UUO will time out if it runs for
more than half a second during a single activation.

If the effective address of this UUO is 636367 (that's 'SSW' in
sixbit) and the AC field is zero, then instead of a spacewar module
being initiated, all your spacewar modules will be killed. This is
the normal way to kill spacewar modules. The RESET UUO (see page
139) and all flavors of the EXIT UUO (see page 138) will also kill
your spacewar modules.

SPCWGO [OP=047, ADR=400003] CALLI 400003
--------------------------------------------------
MOVE AC,[<Bits 0:1 (600000,,0 bits)= processors;
bits 2:3 (140000,,0 bits)= timeout suppression;
bits 14:17 (000017,,0 bits)= startup interval;
bits 18:35 (0,,777777 bits)= starting address>]
SPCWGO AC,

The SPCWGO UUO is used to initiate a spacewar process on either the
PDP-6 or the PDP-10 or both. The starting address of the spacewar
module should be in the right half of the AC. Bits 14:17 (17,,0
bits) of the AC should contain the time in 60ths of a second between
startups of the spacewar module. A zero time means run the spacewar
process only once and then kill it. Bits 0:1 (600000,,0 bits)
determine which processor(s) will run this module. If bit 0
(400000,,0 bit) is a one, then the module will be run on the PDP-10;
if bit 1 (200000,,0 bit) is a one, the module will be run on the
PDP-6. If both bits 0 and 1 are one, then both processors will run
this module, with each processor starting at the given starting
address. If both bits 0 and 1 are zero, then the module will be run
on the PDP-6 unless the PDP-6 is dead, in which case the module will
be run on the PDP-10. Bits 2:3 (140000,,0 bits) are used to specify
timeout suppression separately for the PDP-10 process (bit
2--100000,,0 bit) and the PDP-6 process (bit 3--40000,,0 bit). If
the timeout-suppression bit is off for a process, then that process
will time out if it runs for more than half a second during a single
activation. The remaining bits in AC (bits 4:13--the 37760,,0 bits)
are reserved for future use.

EXAMPLE: To initiate a spacewar process with starting address WAR to
run every 17 ticks on the PDP-10 without timeout suppression, do the
following:

MOVE AC,[400017,,WAR]
SPCWGO AC,
8.1 Spacewar UUOs Spacewar Mode 114

DISMIS [OP=047, ADR=400024] CALLI 400024
--------------------------------------------------
DISMIS

The DISMIS UUO is used by spacewar processes to terminate individual
activations. This UUO causes the process to be stopped until the
next time it is supposed to be run, at which time the process will be
restarted at its starting address.

This UUO has another (though similar) meaning in the user interrupt
system; its meaning there is explained on page 124.
9. User Interrupts User Interrupts 115

SECTION 9

USER INTERRUPTS

The user interrupt system allows a program to take action upon the
occurrence of any of various special conditions, without the program
having to test continuously for these conditions. There are two
versions of interrupts available--the old style and the new style.
The main differences between the two are: 1) while you are processing
an old style interrupt you can still be interrupted, which can cause
all sorts of trouble, but while you are processing a new style
interrupt you cannot receive another interrupt until you dismiss the
current one; 2) the only interrupts you can receive with the old
system are processor interrupts such as push-down overflow, illegal
memory reference and arithmetic overflow. You can also enable for
clock interrupts with the old system, but only clock ticks that occur
while you are actually running will be seen by your program. All
interrupts are possible with the new system; and clock interrupts
will happen whether or not you are actually running at the time.
Before going into more differences between the old and new style
interrupts, I shall explain the basics of the interrupt system and
the features that are the same for both styles.

A user program indicates that it wants to use the interrupt system by
enabling itself for the particular interrupts that it is interested
in. Interrupt conditions that are not enabled for will be handled by
the system. For instance, if you get a push-down overflow, and if
you are not enabled for push-down overflow interrupts, then you will
get the system error message PDL OV. If, on the other hand, you ARE
enabled for this interrupt, then you will get an interrupt indicating
that you had a push-down overflow. Some interrupt conditions are
ignored by the system unless you are enabled for them.

When an interrupt that you are enabled for does occur, your program
is stopped, the program counter (PC) and PC flags are saved in JOBTPC
in your job data area (see Appendix 4), the cause of the interrupt
is saved in JOBCNI and your interrupt handler is started at the
address contained in JOBAPR.

The PC that you get in JOBTPC generally points to the next
instruction that your main process would otherwise have executed if
the interrupt had not occurred. However, there are certain
conditions under which the value of this PC is not quite obvious.

First of all, if you were executing a UUO (and hence your PC was in
monitor mode while executing some system code for that UUO), then the
9. User Interrupts User Interrupts 116

PC saved in JOBTPC will not be your real (monitor mode) PC that you
had at the time of the interrupt; instead JOBTPC will contain the
location of the UUO call in your core image, and the user-mode bit
(bit 5--the 10000,,0 bit) in the left half of JOBTPC will be OFF to
indicate this condition.

Secondly, when you receive a processor interrupt (either old or new
style) such as illegal memory reference, the PC saved in JOBTPC will
point to the instruction that caused the interrupt. However, if you
jump to an illegal location, then the PC returned with the illegal
memory reference interrupt will point to the illegal location. For
instance, on an AOJA 1,777777, the AC will have been incremented and
the PC changed to 777777 before the ill mem ref occurs, so the PC
stored in this case would be 777777.

Finally, if an interrupt occurs in the middle of an ILDB or an IDPB
instruction after the byte pointer has been incremented but before
the byte has been moved, then JOBTPC will point to the byte
instruction and the byte-increment suppression flag (bit 4--the
20000,,0 bit), will be on in the left half of JOBTPC. Thus the byte
pointer will not be incremented again when (and if) the instruction
is resumed.

Each condition for which an interrupt can occur is represented by a
specific bit. You enable a given interrupt by setting to one the bit
corresponding to that condition; this can be done with various UUOs
that will be described in detail later. When you get an interrupt,
the bit representing the cause of the interrupt is given to you in
the word at JOBCNI. For new style interrupts this word will have
exactly one bit on. With old style interrupts there may be some
extraneous bits on that do not represent old style interrupts. The
word returned in this case is the CONI word from the processor, and
the extra bits currently set in this word are the 0,,6043 bits.

The interrupt conditions represented by the different bits are listed
below. The bits marked with asterisks (*'s) represent the only
conditions for which you can receive interrupts under the old style
interrupt system. You are not allowed to enable a given interrupt
condition for both old and new style interrupts at the same time.

NOTE: The RESET UUO (see page 139) clears all of your interrupt
enablings.
9. User Interrupts User Interrupts 117

BITS OCTAL NAME INTERRUPT CONDITIONS

0 400000,,0 INTSWW Your job is about to be
swapped out.

1 200000,,0 INTSWD Your job has just been swapped
back in. If you enable for
both INTSWW and INTSWD, then
you will receive these two
interrupts as a pair in the
expected order every time your
job is swapped.

2 100000,,0 INTSHW Your job is about to be
shuffled.

3 40000,,0 INTSHD Your job has just been
shuffled.

4 20000,,0 INTTTY Your user-level job would be
activated by TTY input if it
were waiting for it. When you
are enabled for this
interrupt, you will be
interrupted every time either
a character or a line is typed
in, depending on whether you
are in character mode or line
mode. As long as you do not
ask for more than there is in
the TTY input buffer, you may
read from the terminal at
interrupt level.

5 10000,,0 INTPTO A PTY job has just gone into a
wait state waiting for you to
send it characters.

6 4000,,0 INTMAIL Someone has just sent you a
letter (see Section 7). You
may read the letter at
interrupt level.

7 2000,,0 INTWAIT A UWAIT UUO has just returned
from finishing the execution
of a UUO. You cannot enable
for this interrupt, which is
used by the monitor to make
9. User Interrupts User Interrupts 118

the UWAIT UUO work (see page
124).

8 1000,,0 INTPTI A PTY you own has just sent
you a character (or line).

9 400,,0 INTPAR A parity error has occurred in
your core image. The address
in which bad parity was
detected is given to you in AC
10.

10 200,,0 INTCLK A clock interrupt has just
happened. The default
interval between clock
interrupts is a 60th of a
second; this interval can be
changed by the CLKINT UUO (see
page 123), which also enables
clock interrupts. This bit is
for new style clock interrupts
only.

11 100,,0 INTINR IMP interrupt from foreign
receive side. See Section
13.12, specifically page 202,
for explanations of this and
the following three interrupt
conditions.

12 40,,0 INTINS IMP interrupt from foreign
send side.

13 20,,0 INTIMS IMP status change interrupt.

14 10,,0 INTINP IMP input waiting.

15 4,,0 INTTTI [ESCAPE] I has just been typed
on the display terminal which
is attached to this job.

16 2,,0 INTQXF Your job is changing queues.
Your new positive queue number
is available from accumulator
14; see page 121. Note: This
interrupt is not guaranteed to
be generated every time you
change queues.
9. User Interrupts User Interrupts 119

19 0,,200000 * POV A push-down stack overflow or
underflow has just occurred.
If the instruction causing
this was a PUSHJ or a POPJ,
then the PC stored in JOBTPC
is the one specified by the
instruction (PUSHJ) or by the
stack (POPJ); if the
instruction is a PUSH or a
POP, then the PC will have
been incremented and will thus
point to the instruction after
the PUSH or POP. In any case,
the push-down pointer will
have been given its new value
and any value being pushed or
popped will have been moved to
its indicated destination.
For a PUSHJ or a PUSH, the
value pushed will now be
occupying the last location in
the stack. For a POPJ or a
POP, the value popped will
have come from the first
location before the beginning
of the stack.

22 0,,20000 * ILM An illegal memory reference
has just occurred; that is,
you have just tried to
reference a memory location
outside your core image.

23 0,,10000 * NXM A non-existent memory
reference has just occurred;
that is, you have just tried
to reference a memory location
that apparently does not
exist. This should never
really happen; if it does, it
generally means a memory unit
has failed.

26 0,,1000 * The clock has just ticked
while you were running. This
bit is for old style clock
interrupts only.
9. User Interrupts User Interrupts 120

29 0,,100 * INTFOV A floating overflow has just
occurred. The PC saved will
point to the word after the
instruction causing the
overflow.

32 0,,10 * INTOV An integer overflow has just
occurred. The PC saved will
point to the word after the
instruction causing the
overflow.

The remaining bits are currently unused. As new interrupts are added
they will use the lower-numbered available bits.

9.1 New Style Interrupts

The new interrupt system is highly recommended over the old system;
thus I will explain the new system first. The bit representations of
the particular interrupts are the same in both systems (except for
clock interrupts), but with the new system there are more interrupts
which you can enable.

When you receive a new style interrupt, all sorts of things happen.
First of all, as usual your PC and flags are saved in JOBTPC and the
bit representing the cause of the interrupt is stored in JOBCNI.
Unless you were executing a UUO at the time of the interrupt, the PC
word in JOBTPC will be perfectly accurate. If, however, you WERE
executing a UUO, then the PC saved in JOBTPC is really the address in
your core image where the UUO in progress is located; in this case,
the user-mode bit (bit 5--the 10000,,0 bit) in JOBTPC will be off.
Thus the user-mode bit in JOBTPC will tell you if a UUO was in
progress when the interrupt occurred.

With a new style interrupt, your accumulators are saved. Then,
before your interrupt routine is started, certain ACs are loaded up
with data as listed in the table below. Your user-level ACs are
saved in locations 20:37 of your core image unless you were executing
a UUO at the time of the interrupt, in which case your ACs are saved
somewhere in the system.
9.1 New Style Interrupts User Interrupts 121

AC CONTENTS

1 The current value of the spacewar buttons. See the
SPWBUT UUO on page 149.

2 Your current protection-relocation constant.

3 A warning value. This AC usually contains zero but is
set up with -1 if this is the last interrupt you will
get before your job is swapped out or shuffled.

4 The number of the processor this interrupt module is
running on. This number is 1 for the PDP-10 and 2 for
the PDP-6. Since interrupts are (currently) always
run on the PDP-10, this AC will always contain 1.

5 A flag indicating the status of the processor that
this interrupt-level process is NOT running on. This
flag is zero if that processor is running (normal
state) and -1 if that processor is dead.

6 Your job status word. See the JBTSTS UUO on page 101.

7 JOBREL for your upper segment, if any. This is the
size, minus one, of your upper segment, if you have
one, and zero if you do not.

10 The datum for this particular interrupt. Currently,
the only interrupt with a datum is the parity error
interrupt, for which you get here the address at which
bad parity has been detected. This value can be
invalid if you have some pending interrupts which
generate data (e.g., if you get several parity errors
in a row), in which case this is the last datum seen
by the system.

14 Your positive queue number. This tells you which
queue your user-level process is in.

After these ACs have been set up, your interrupt routine is run at
interrupt level starting at the address contained in the right half
of JOBAPR. The PC flags for your interrupt-level routine are set
from the bits in the left half of JOBAPR. (The PC flags are
explained in Appendix 3.) For example, if bit 6 (the 4000,,0 bit)
in JOBAPR is on, your interrupt process will be started up in
IOT-USER mode (see Appendix 3). Your interrupt process is actually
started by the system doing a JRST 13,@JOBAPR (see the JRST
instruction in the PDP-10 manuals) and you are then allowed to run
9.1 New Style Interrupts User Interrupts 122

uninterrupted (except for I/O interrupt services) for up to 8 ticks
(8/60 of a second). If you are still running at interrupt level when
that time runs out, you will get the system error message I-LEVEL
TIMEOUT and your program will be stopped.

When your interrupt-level routine finishes and wishes to return to
the interrupted program, it should issue the DISMIS UUO (see page
124). If, however, the interrupt-level routine does not wish to
return to the user-level program but wants instead to BECOME the
user-level program, then it should issue the UWAIT UUO and then the
DEBREAK UUO. This lets your interrupt-level process keep running,
but it will no longer be at interrupt level; it will be running at
user level. Note that neither UWAIT (see page 124) nor DEBREAK (see
page 125) causes any change in your PC flags. Thus, if you are in
IOT-USER mode when you give these UUOs, then you will still be in
IOT-USER when you return from them! If you UWAIT and DEBREAK and
THEN want to return to the interrupted program, you can do so simply
by jumping to the interrupted address (contained in JOBTPC) by doing
a JRST 2,@JOBTPC which will also restore the flags of the interrupted
process. However, you should probably save JOBTPC somewhere else
before DEBREAKing because after you DEBREAK you can receive another
interrupt, which would clobber the old JOBTPC with a new one.

To allow users to enable both old and new style interrupts at the
same time, a user program can indicate a special three word block to
be used with NEW STYLE interrupts in place of the three words at
JOBCNI, JOBTPC and JOBAPR, respectively. If JOBINT in your job data
area contains a non-zero number, that number will be interpreted as
the address of this three word block. The normal three words in the
job data area will continue to be used for old style interrupts (and
for new style interrupts whenever JOBINT contains zero).

Now here are the UUOs used with the new style interrupt system.

INTENB [OP=047, ADR=400025] CALLI 400025
--------------------------------------------------
MOVE AC,[<interrupt bits to be enabled>]
INTENB AC,

The INTENB UUO enables the interrupts that correspond to the bits on
(ones) in the AC and disables the interrupts corresponding to bits
that are zero. This overrides all previous enablings (of the new
style interrupts). If there is an interrupt pending that you are now
enabling, the interrupt will be taken immediately. (See page 117 for
the interrupt conditions represented by the various bits.)
9.1 New Style Interrupts User Interrupts 123

INTORM [OP=047, ADR=400026] CALLI 400026
--------------------------------------------------
MOVE AC,[<bits to be ORed in>]
INTORM AC,

The INTORM UUO enables the interrupts corresponding to the bits that
are on (ones) in the AC. The enablings of other interrupts are
unchanged.

INTACM [OP=047, ADR=400027] CALLI 400027
--------------------------------------------------
MOVE AC,[<bits to be cleared>]
INTACM AC,

The INTACM UUO disables the interrupts corresponding to the bits that
are on (ones) in the AC. The enablings of other interrupts are
unchanged.

INTENS [OP=047, ADR=400030] CALLI 400030
--------------------------------------------------
INTENS AC,

The INTENS UUO returns your new style interrupt enablings in the AC;
bits which are on (ones) represent enabled interrupts.

CLKINT [OP=717]
--------------------------------------------------
CLKINT 1,<number of ticks between interrupts>

The CLKINT UUO is used to set the interval between clock interrupts.
If you enable for clock interrupts without using this UUO, you get
the default interval of one tick (a 60th of a second); but with this
UUO you can set the number of ticks per clock interrupt to any number
representable in 18 bits (up to about an hour and twelve minutes).

This UUO enables for clock interrupts, masks clock interrupts on (see
the INTMSK UUO on page 127), and sets the interval (in ticks) between
interrupts to the number which is the effective address of the UUO.
The AC field of this UUO must be a 1, as shown.
9.1 New Style Interrupts User Interrupts 124

DISMIS [OP=047, ADR=400024] CALLI 400024
--------------------------------------------------
DISMIS

The DISMIS UUO is used to terminate an interrupt-level process. When
you give this UUO at interrupt level, the current interrupt is
dismissed and your user-level program is continued at the point where
it was interrupted. This UUO is illegal at user level. (The DISMIS
UUO has another related meaning when given by a spacewar process; see
page 114.)

UWAIT [OP=047, ADR=400034] CALLI 400034
--------------------------------------------------
UWAIT

The UWAIT UUO can be used by an interrupt-level process to ensure
that the interrupted program is not in the middle of executing a UUO.
If a UUO was in progress when the interrupt occurred, then UWAIT will
wait for that UUO to finish. UWAIT also returns with your user-level
ACs set up (i.e., the ACs that were saved when the interrupt
occurred), so you should not expect any ACs to be preserved through a
UWAIT.

The mechanism used by UWAIT is the following. If no UUO is in
progress, UWAIT sets up your user-level ACs and returns immediately.
Otherwise, bit 7 (2000,,0 bit) in your interrupt enablings is turned
on, the address of the instruction after the UWAIT (to which you will
want to return later) is saved, and your user-level process is
resumed, in the middle of some UUO. When that UUO finishes
execution, the system notes that you are enabled (bit 7) for a
UUO-completion interrupt; so bit 7 is cleared and your
interrupt-level routine is continued at the saved address, with your
user-level ACs already having been set up. At this point you are
once again at interrupt level and are subject to its timeout.

After you have done a UWAIT, you can terminate your interrupt-level
process with either of two UUOs. You can DISMIS and leave interrupt
level the normal way with no side effects for having done the UWAIT,
or you can DEBREAK to make your interrupt-level process into your
user-level process (see the DEBREAK UUO below for more details).

If you do a UWAIT and do not return immediately, then while the
interrupted UUO is finishing other interrupts may occur and you may
even do another UWAIT. When the UUO finally completes, the
interrupt-level routine to regain control will be the last one that
did a UWAIT.
9.1 New Style Interrupts User Interrupts 125

If you are in the middle of a SLEEP UUO (see page 138) when you do a
UWAIT, the SLEEP is terminated immediately; you do not wait until the
time when it would normally have ended.

The UWAIT UUO is illegal except at interrupt level.

DEBREAK [OP=047, ADR=400035] CALLI 400035
--------------------------------------------------
DEBREAK

The DEBREAK UUO is used to turn an interrupt-level process into a
user-level process. In order to assure that you were not in the
middle of a UUO when the interrupt occurred, you should give a UWAIT
UUO before you DEBREAK. After debreaking, you will no longer be at
interrupt level. However, you will have the same accumulators that
you had before debreaking. DEBREAK does not alter the flow of
instructions (as DISMIS does); the next instruction executed is the
one following the DEBREAK, but it will be executed at user level.

After you do a UWAIT and a DEBREAK, you can return to your
interrupted process by jumping to the address that was placed in
JOBTPC when the interrupt started. Note, however, that as soon as
the DEBREAK is done, you may receive further interrupts since you are
now at user level; thus JOBTPC may get clobbered, so you might want
to save it before you DEBREAK. See also the INTJEN UUO on page 128.

The DEBREAK UUO is illegal except at interrupt level.

IWAIT [OP=047, ADR=400040] CALLI 400040
--------------------------------------------------
IWAIT

The IWAIT UUO causes your job to go into a wait state (INTW) that
will be terminated only when an interrupt occurs.
9.1 New Style Interrupts User Interrupts 126

IENBW [OP=047, ADR=400045] CALLI 400045
--------------------------------------------------
MOVE AC,[<interrupt bit enablings>]
IENBW AC,

The IENBW UUO is used to set your interrupt enablings and to put your
user-level process into the interrupt-wait state, both at the same
time in order to prevent a race between going into interrupt wait and
getting an interrupt. This UUO has the same effect (except for
timing) that would be gotten from doing an INTENB followed by an
IWAIT.

INTGEN [OP=047, ADR=400033] CALLI 400033
--------------------------------------------------
MOVE AC,[<bits to interrupt with>]
INTGEN AC,

The INTGEN UUO generates an interrupt for you for each bit on in the
AC. This will cause the interrupts to take place immediately, but
you must be enabled for all of the interrupts you are generating or
you will get a system error message.

INTIRQ [OP=047, ADR=400032] CALLI 400032
--------------------------------------------------
INTIRQ AC,

The INTIRQ UUO returns in AC the bits representing the interrupts you
currently have pending. Usually this will be zero unless you are at
interrupt level. This will also be non-zero if between the time an
interrupt is requested and the time it is serviced it is disabled,
which can happen if your interrupt-level routine changes the
interrupt enablings. Finally, this can be non-zero if you have
masked off some interrupts (see the INTMSK UUO below).
9.1 New Style Interrupts User Interrupts 127

INTMSK [OP=720]
--------------------------------------------------
INTMSK 1,ADR

ADR: <interrupt mask>

The INTMSK UUO is used to set your interrupt mask. In this mask, a 1
means the interrupt is masked on, a 0 means it is masked off. Your
interrupt mask is initially all 1's. The only interrupts you can
receive are those that are both enabled and masked on. If an enabled
interrupt is masked off (with this UUO or with one of the following
UUOs), then when that interrupt condition arises, the interrupt will
remain pending until it is masked back on, at which time it will
interrupt immediately. (The AC field of the UUO must be a 1, as
shown.)

IMSKST [OP=721]
--------------------------------------------------
IMSKST 1,ADR

ADR: <bits to be turned on in interrupt mask>

The IMSKST UUO ORs the contents of location ADR into your interrupt
mask (see the INTMSK UUO above). Thus this masks ON the indicated
interrupts. (The AC field of the UUO must be a 1, as shown.)

IMSKCL [OP=722]
--------------------------------------------------
IMSKCL 1,ADR

ADR: <bits to be turned off in interrupt mask>

The IMSKCL UUO turns off, in your interrupt mask, the bits that are
on in location ADR. Thus this masks OFF the indicated interrupts.
See the INTMSK UUO above. (The AC field of the UUO must be a 1, as
shown.)
9.1 New Style Interrupts User Interrupts 128

INTUUO [OP=723]
--------------------------------------------------
INTUUO <function>,ADR

INTUUO is an interrupt system extended UUO that uses the AC field to
determine which of several functions is to be executed. The
different functions are described separately below.

INTJEN [OP=723, AC=0] INTUUO 0,
--------------------------------------------------
INTJEN ADR

ADR: <interrupts bits to be ORed in>
<PC word to go to>

The INTJEN UUO solves an special race condition. Suppose you have
done a UWAIT followed by a DEBREAK, fooled around in user level for a
while, and now wish to enable your interrupts again and return to the
original user-level process. You presumably have the PC word stored
in a location somewhere. If you enable your interrupts and then try
to jump back to the original user-level process, you may get
interrupted between the enabling UUO and the jump. The second
interrupt may want to do the same thing and may in the process
overwrite your PC word with a new and different PC. This UUO solves
this race by setting the interrupt bits at ADR and jumping to the PC
contained in ADR+1 all in one indivisible operation, so that if
another interrupt occurs, the PC it gets will be the one specified in
ADR+1.

IMSTW [OP=723, AC=1] INTUUO 1,
--------------------------------------------------
IMSTW ADR

ADR: <mask bits>
1

The IMSTW UUO sets your interrupt mask (see the INTMSK UUO above) and
then puts you into INTERRUPT WAIT. The effective address of the
instruction indicates a two word block, the first word of which
should have the mask bits you want set. The second word of the block
must contain a 1, as shown.
9.1 New Style Interrupts User Interrupts 129

IWKMSK [OP=723, AC=2] INTUUO 2,
--------------------------------------------------
IWKMSK ADR

ADR: <bits for interrupts that should awaken>

The IWKMSK UUO sets the mask that determines if the main job gets
awakened out of IWAIT when an interrupt happens. If an interrupt
occurs that should not awaken you, then it is processed but when it
finishes, your main job will not be taken out of interrupt wait.

INTDMP [OP=723, AC=3] INTUUO 3,
--------------------------------------------------
INTDMP ADR
<error return - error code in ADR+1>

ADR: <job name or number>
<block of 5 words for returned information>

Error codes:

2 ambiguous job name
3 non existent job name

The INTDMP UUO returns 5 words of information about a particular job.
The effective address of the UUO specifies a six word block; the
first word of this block should contain the number or sixbit name of
the job you want to find out about, where zero means your own job.
If the UUO is successful, the skip return is taken and words 1
through 5 of the block are filled with the information indicated
below. If the value in ADR specifies an ambiguous or non-existent
job, then the error return (no skip) is taken and an error code (see
above) is returned in ADR+1.

WORD VALUE

0 Unchanged (job name or number).
1 Interrupt enable bits of specified job.
2 Interrupt mask.
3 Zero.
4 Wakeup mask (interrupt bits which will awaken the job
from IWAIT; see IWKMSK UUO above).
5 Number of the queue the job is in.
9.1 New Style Interrupts User Interrupts 130

INTIPI [OP=723, AC=4] INTUUO 4,
--------------------------------------------------
INTIPI ADR
<error return - code in ADR+1>

ADR: <job name or number>
<bits for interrupts you want generated>

Error codes:

1 non existent job number
2 ambiguous job name
3 non existent job name
4 job not enabled for interrupts specified

The INTIPI UUO is used to send one or more interrupts to any job on
the system. ADR should contain the number or sixbit name of the job
you want to receive the interrupt(s). The specific interrupts you
want generated should be indicated by bits on in the word at ADR+1.
The job you choose must be enabled for the interrupts you send. If
this UUO is successful, the skip return is taken; otherwise, the
error return (no skip) is taken and an error code is returned in the
word at ADR+1.

IMSKCR [OP=723, AC=5] INTUUO 5,
--------------------------------------------------
IMSKCR ADR

ADR: <bits to be turned off in interrupt mask>

The IMSKCR UUO turns off, in your interrupt mask, the bits that are
on in location ADR. Thus this masks OFF the indicated interrupts.
After masking off these interrupts, this UUO returns your OLD mask in
the word at ADR. This avoids timing errors in saving and restoring a
mask. See the INTMSK UUO above.

9.2 Old Style Interrupts

When you receive an interrupt under the old interrupt system, here is
what happens: Your PC and flags are saved in JOBTPC, the CONI word
from the processor is stored in JOBCNI (one old style interrupt bit
will be on in this word indicating the cause of the interrupt), and
9.2 Old Style Interrupts User Interrupts 131

your PC is changed to that in the right half of JOBAPR. Your
interrupt routine may run as long as it wants; as far as the system
is concerned, your interrupt routine is now your main process and no
further special action will be taken by the system for the interrupt.
When your interrupt routine is finished, it can do a

JRST 2,@JOBTPC

to return to the interrupted program. This will restore the PC and
flags to their states when the interrupt occurred.

Note that since your interrupt routine is not treated at all
specially by the system, it can be interrupted itself by an interrupt
of the same or a different type. If this happens, JOBTPC and JOBCNI
will be clobbered with the values for the second interrupt; then when
processing resumes for the first interrupt, the address (in the main
program) to which control should return will no longer be in JOBTPC.
Unless this address was saved by your interrupt handler, the program
will probably not be able to continue successfully. The new
interrupt system avoids this problem by not allowing you to be
interrupted while you are processing a new style interrupt.

The processor CONI word stored in JOBCNI with old style interrupts
will have some extraneous bits on in addition to the bit representing
the interrupt. The extra bits currently set in this word are the
0,,6043 bits.

Here are a couple of UUOs to enable old style interrupts.

APRENB [OP=047, ADR=16] CALLI 16
--------------------------------------------------
MOVE AC,[<interrupt bits to be enabled>]
APRENB AC,

The APRENB UUO enables your job to receive old style interrupts upon
any of the conditions represented by the bits in the AC. Only bits
19, 22, 23, 26, 29 and 32 (0,,231110 bits) can be enabled by the old
interrupt system. See page 119 for the interrupt conditions these
bits represent.
9.2 Old Style Interrupts User Interrupts 132

SETPOV [OP=047, ADR=32] CALLI 32
--------------------------------------------------
MOVEI AC,<address of interrupt routine>
SETPOV AC,

The SETPOV UUO is used to enable for old style interrupts on
push-down stack overflow and underflow. This UUO takes the address
in AC and stores it in JOBAPR; thus this should be the address of
your interrupt handling routine. Then you are enabled for old style
push-down interrupts, with any previous old style enablings
discarded. Thus you cannot use this UUO if you want any old style
interrupts other than push-down overflow/underflow.
10. Fast Bands Fast Bands 133

SECTION 10

LIBRASCOPE FAST BAND STORAGE

User programs are allowed to use bands on the Librascope disk for
fast secondary storage. However, because the system uses Librascope
bands for holding swapped out jobs and because there are only a
limited number of bands, user programs should not depend on this
resource too heavily. The system may crash if there are not enough
bands for swapping.

Librascope storage is allocated in bands, with each band being
=76 * =1024 (76K) words long. Each band has =2432 sectors (numbered
from 0 to =2431); and each sector is =32 words long. When reading or
writing a fast band, you specify the number of the sector at which
the transfer is to start and the number of words to be read or
written. The number of words should always be a multiple of =32; if
it isn't, then it will be increased by the system to the next
multiple of =32 and that many words will be transferred, whether you
like it or not. If you read or write past the end of sector number
=2431, you will actually be reading/writing at the beginning of the
band (starting over with sector 0).

When requesting a Librascope fast band (with the UFBGET UUO, page
134) you may specify EITHER a logical band number from 0 to 37 by
which you can refer to the band that you are given OR the physical
number of a particular band that you want. A band number is taken as
a physical band number if it has the 400000 bit on; otherwise, it
will be interpreted as a logical band number. When you have been
assigned a fast band, you can expect it to contain whatever garbage
was last written on it.

Each fast band has associated with it a sector offset which indicates
where the logical beginning of the band (sector 0) is located
relative to the physical beginning of the band. The value of this
offset is generally irrelevant to the user except when he may want to
try to reclaim a particular band after some sort of catastrophe, such
as a system restart. At such a time, the user might want to tell the
system where on a particular band his data starts. This sector
offset can be set to a specific value with the UFBGET UUO, and it can
be determined (for instance when set by the system) for a particular
band with the UFBPHY UUO (see page 136). The value of the offset is
always between 0 and =1215 inclusive.
10.1 Getting and Releasing Fast Bands Fast Bands 134

10.1 Getting and Releasing Fast Bands

Here are the UUOs used to obtain and release Librascope fast bands.

UFBGET [OP=047, ADR=400010] CALLI 400010
--------------------------------------------------
MOVE AC,[<enable bits and offset>,,<band number>]
UFBGET AC,
<return if no bands available>

The UFBGET UUO is used to acquire one Librascope band. The right
half of AC should contain EITHER the logical band number (from 0 to
37) by which you will refer to the band you get OR the physical
number of a particular band that you want; physical band numbers must
have the 400000 bit on. Bits 1 (200000,,0 bit) and 2 (100000,,0 bit)
of AC are write- and read-enabling bits, respectively, which, if on,
allow other jobs to write and/or read this fast band of yours. Bits
7:17 (3777,,0 bits) of AC should contain the sector offset which you
wish this band to have, where zero means the system should choose
whatever offset it wants (see the above explanation of the offset).
To get a real offset of zero, turn on bit 0 (400000,,0 bit) in the AC
and make bits 7:17 zero.

If this UUO is successful, it takes the skip return and the physical
number of the band assigned to you is returned in AC (but without the
400000 bit on). If there are no bands available, or if a particular
band you have requested is unavailable, the direct (error) return is
taken.

UFBGIV [OP=047, ADR=400011] CALLI 400011
--------------------------------------------------
MOVEI AC,<band number>
UFBGIV AC,

The UFBGIV UUO releases the fast band whose number is in the AC.
This number should have the 400000 bit on if it is a physical band
number; otherwise, it will be interpreted as a logical band number.

The RESET UUO (see page 139) releases all fast bands assigned to you.
10.1 Getting and Releasing Fast Bands Fast Bands 135

UFBCLR [OP=047, ADR=400012] CALLI 400012
--------------------------------------------------
UFBCLR

The UFBCLR UUO releases all fast bands assigned to you.

10.2 Reading and Writing Fast Bands

The UUOs used to read and write Librascope fast bands are described
below.

FBREAD [OP=706]
--------------------------------------------------
MOVEI AC,<band number>
FBREAD AC,ADR
<error return>

ADR: <no-wait flag (sign bit)>,,<address where data is to go>
<number of words to be read>
<sector address of beginning of transfer>

The FBREAD UUO causes data to read into your core image from the fast
band whose logical or physical band number is in the AC. The
effective address of the UUO should point to a three-word block (as
shown above) which contains the following values: 1) the address
where the data is to be deposited in your core image, 2) the number
of words to be read and 3) the number of the sector at which reading
is to start. If the sign bit (400000,,0 bit) of the first word of
this block is ON, then this UUO will return immediately without
waiting for the transfer (although it will wait for any previously
initiated transfer to finish); if the sign bit is OFF, the FBREAD UUO
will not return until the data transfer has been completed.

If there are no errors during the read (or during the initiation of
the read if the no-wait bit is on), this UUO will take the skip
return. Upon an error (including a request to read a band that you
are not permitted to read), the direct return will be taken.
10.2 Reading and Writing Fast Bands Fast Bands 136

FBWRT [OP=707]
--------------------------------------------------
MOVEI AC,<logical fast band number>
FBWRT AC,ADR
<error return>

ADR: <no-wait flag (sign bit)>,,<address of data>
<number of words>
<beginning sector number>

The FBWRT UUO causes data to be written from your core image onto the
fast band whose logical or physical band number is in AC. The
effective address of the UUO should point to a three word block (as
shown above) which indicates 1) where the data to be written out is
located, 2) the number of words to be written and 3) the number of
the sector at which writing is to start. If the sign bit (400000,,0
bit) of the first word of this block is ON, then this UUO will return
immediately without waiting for the transfer (although it will wait
for any previously initiated transfer to finish); if the sign bit is
OFF, the FBWRT UUO will not return until the data transfer has been
completed.

If this UUO is successful, the skip return will be taken. Upon an
error, the direct return will be taken.

10.3 Miscellaneous Fast Band UUOs

Here are some special UUOs provided for finding out various
information about the status of Librascope fast bands.

UFBPHY [OP=047, ADR=400055] CALLI 400055
--------------------------------------------------
MOVE AC,<logical or physical band number>
UFBPHY AC,

The UFBPHY UUO returns the physical band number and offset of the
Librascope fast band indicated in AC. The offset is returned in AC
left; the physical band number is returned in AC right (but without
the 400000 bit on). Bit 1 (200000,,0 bit) in AC will be on if you
have write access to the band, and bit 2 (100000,,0 bit) will be on
if you have read access. Zero will be returned in AC if there is no
such band.
10.3 Miscellaneous Fast Band UUOs Fast Bands 137

UFBSKP [OP=047, ADR=400056] CALLI 400056
--------------------------------------------------
UFBSKP
<transfer in progress>
<no transfer in progress>

The UFBSKP UUO simply skips unless you have a Librascope fast band
transfer in progress, in which case the direct return is taken.

FBWAIT [OP=047, ADR=400057] CALLI 400057
--------------------------------------------------
FBWAIT

The FBWAIT UUO simply waits until any fast band transfer in progress
finishes. If you have don't have a transfer going on when you call
it, it will return immediately.

UFBERR [OP=047, ADR=400060] CALLI 400060
--------------------------------------------------
UFBERR
<error occurred>
<no error>

The UFBERR UUO simply skips unless your last fast band transfer
encountered an error; if you had an error, then the direct return is
taken.
11. Misc. UUOs Misc. UUOs 138

SECTION 11

MISCELLANEOUS UUOS

This section describes various UUOs which did not seem to fit in any
other sections. These UUOs include the common and useful EXIT,
SLEEP, RESET and SWAP UUOs; also in this section are the UUOSIM and
TMPCOR UUOs.

EXIT [OP=047, ADR=12] CALLI 12
--------------------------------------------------
EXIT <ac>,

The EXIT UUO is used to cause your program to stop and exit to the
monitor. If <ac> is 0, then all I/O channels you have open will be
closed (as if by the RELEAS UUO with no inhibit bits on; see page
33), then a RESET (see the RESET UUO below) will be done and you will
not be permitted to CONTINUE your program after exiting. If <ac> is
1, then this UUO will not affect any of your I/O channels nor will it
do a RESET; a subsequent CONTINUE monitor command will cause your
program to resume execution at the instruction immediately following
the "EXIT 1," instruction. Other values of <ac> are reserved for
future use.

Both forms of this UUO kill any spacewar modules you have.

A phantom or detached job giving either form of this UUO will have
its I/O channels closed, and then the job will be killed.

SLEEP [OP=047, ADR=31] CALLI 31
--------------------------------------------------
MOVEI AC,<number of seconds to sleep>
SLEEP AC,

The SLEEP UUO causes your job to be stopped for the number of seconds
specified by the contents of the AC, which is interpreted
(approximately) modulo =69. If AC contains zero, your job will sleep
for 1/60 of a second. When the sleep time is up, your program is
resumed at the instruction immediately after the SLEEP. If you type
Control-C or receive an interrupt while you are sleeping, the SLEEP
is terminated immediately.
11. Misc. UUOs Misc. UUOs 139

RESET [OP=047, ADR=0] CALLI 0
--------------------------------------------------
RESET

The RESET UUO is used to reset various conditions pertaining to your
job. All monitor commands that get a new program into your core
image do a RESET first. Also, the "EXIT 0," UUO (see above) does a
RESET just before exiting. Here is a list of the things that happen
when a RESET is done:

All your I/O channels are released without being closed.
That is, the result is the same as that from doing a
RELEAS <channel>,3 for every channel you have open. See the
RELEAS UUO on page 33.

The state of program-controllable echoing of typed characters
is reset to echo all characters. This is done by clearing
the NOECHO bit (bit 28--the 0,,200 bit) and the NOECHB bit
(bit 27--the 0,,400 bit) in the TTY I/O status word (see
Section 13.2). See also Section 3.1.

The special-activation-mode bit (bit 11--the 100,,0 bit) is
cleared in your line characteristics word (see the GETLIN UUO
on page 45), and your special activation table is reset to
the standard special activation table. Also, the
linefeed-insertion-inhibition bit (bit 16--the 2,,0 bit) is
cleared in your line characteristics unless you are running
on a PTY.

JOBFF in your job data area is reset from the value in the
left half of JOBSA. See Appendix 4.

Your user interrupt enablings (both new and old style) are
cleared. See Section 9.

Your core image is unlocked from core. See the LOCK and
UNLOCK UUOs on page 147.

If you have a simulated upper segment (created by the SETPR2
UUO; see page 103), it goes away. Note that this does not
affect any real upper segment you may have.

Any spacewar processes you have are killed. See Section 8.

Any Librascope fast bands you have are released. See Section
10.

If there is a letter in your mailbox, it is thrown away. See
Section 7.
11. Misc. UUOs Misc. UUOs 140

Any pseudo-teletypes (PTYs) you have are released along with
any jobs logged in on those PTYs. See Section 3.5.

Any extra Data Disc channels you have are released. See
Section 4.5.

If you are on a III or Data Disc display, your display is
reset. This means that your page printer is normalized and
any III display programs running are killed. See Section 4.

If you are on a Data Disc display, your video switch map is
reset to the permanent map. See Section 4.6.

If you are on a III or Data Disc display, your audio switch
connection is reset to the permanent connection. See Section
4.7.

SWAP [OP=047, ADR=400004] CALLI 400004
--------------------------------------------------
MOVE AC,[SAVADR,,GETADR]
SWAP AC,

SAVADR: <device name in sixbit>
<file name in sixbit>
<file name extension in sixbit>
<core size in 1K blocks>,,<starting address>
<project-programmer name>

GETADR: <device name in sixbit>
<file name in sixbit>
<file name extension in sixbit>,,<mode bits>
<core size in 1K blocks>,,<starting address increment>
<project-programmer name of file>
<project-programmer name for new job>

The SWAP UUO is used to save your core image in a file and/or get or
run another core image from a file. This UUO can also be used to
create a job and to start up a program on that job. The format of
the files used by this UUO is exactly that of the SAVE, GET, RUN and
R monitor commands. Note that SWAP does not allow saving upper
segments; in fact, SWAP kills your upper segment, if any, before
doing anything else. Also, SWAP does a RESET (see the RESET UUO
above) before saving or getting a core image.

If the left half of the AC is non-zero, then your core image will be
saved in the file described by the block pointed to by the left half
11. Misc. UUOs Misc. UUOs 141

of the AC. After that, if the right half of AC is non-zero, then the
core image contained in the file described by the block pointed to by
the right-half of the AC is run or set up as either your core image
or that of a new job. If both halves of AC contain zero, the SWAP
UUO is a no-op.

Now for a few details.

If the left half of the AC is zero, no core image is saved. If it is
non-zero, it should point to a five-word block which contains (as
shown at SAVADR above) the specifications for the dump file to be
saved. These specifications include the device name, file name and
extension, and project-programmer name for the file, the amount of
core (in 1K blocks) to be saved and the starting address for the dump
file. If the core size is zero, the amount of core you currently
have will be used. If the starting address is zero, the current
starting address of your job will be used. If the starting address
is non-zero, it will be copied into the right half of JOBSA in your
job data area before the core image is saved. If the extension is
zero, 'DMP' will be used. If the project-programmer name is zero,
your current Disk PPN is used (see page 17).

Next, if the right half of AC is zero, then no new core image is run.
If it is non-zero, it should point to a block which contains (as
shown at GETADR above) the specifications for the dump file to be
run. These include the device name, file name and extension, and
project-programmer name of the dump file, the core size it is to be
run in, the starting address increment, some special mode bits and,
if the dump file is to be run as a new job (independent of the job
giving the SWAP UUO), the project-programmer name under which that
job should be logged in. The starting address increment is added to
the starting address saved in the dump file to determine where the
program is to be started. The mode bits are in the right half of the
file extension word and have the following meanings:

BITS OCTAL MEANINGS OF 1'S IN MODE BITS OF SWAP UUO

35 0,,1 The dump file will not be started;
instead, the message JOB SETUP will be
typed out and the job will be put into
monitor mode.

34 0,,2 The right half of GETADR+3 will be taken
as an absolute starting address rather
than as an increment.

33 0,,4 The program will be started on a new job
which will be logged in under the
project-programmer name at GETADR+5; if
11. Misc. UUOs Misc. UUOs 142

this PPN is zero, your logged in PPN
will be used for the new job. If this
bit is off, then the word at GETADR+5 is
ignored.

32 0,,10 If starting up another job (bit 33 on),
the job will be started up as a phantom
rather than as a normal job (see the
WAKEME UUO on page 146). This means
that the JLOG bit in the job status word
(see the JBTSTS UUO on page 101) for the
new job will not be turned on; thus that
job will go away if it hits any sort of
error condition (such as a parity error
or a push-down stack overflow).

When you start up a new job with this UUO by having bit 33 on in
GETADR+2, the job number of the new job is returned in the AC
specified in the UUO. A zero is returned if no new job could be
started because there were no job slots left. When a new job is
successfully started, its ACs are copied from your ACs; but in the AC
specified in the SWAP UUO, the new job will get your job number
instead of its own. Thus the old job is given the number of the new
job and the new job is given the number of the old one.

If the ENTER fails on the file specified at SAVADR, or if the LOOKUP
fails on the file specified at GETADR, an error message will be typed
out and the program stopped.

RUN [OP=047, ADR=35] CALLI 35
--------------------------------------------------
MOVE AC,[<starting address increment>,,GETADR]
RUN AC,

GETADR: <device name in sixbit>
<file name in sixbit>
<file name extension in sixbit>,,<mode bits>
0
<project-programmer name of file>
<core size in 1K blocks>

The RUN UUO is DEC's version of the SWAP UUO. Except for a slightly
different parameter format (see RUN UUO calling sequence above), the
only differences between SWAP and RUN are that with the RUN UUO, no
core image can be saved and no phantom job can be started up (mode
bits 32:33 are ignored). For details, see the SWAP UUO above.
11. Misc. UUOs Misc. UUOs 143

TMPCOR [OP=047, ADR=44] CALLI 44
--------------------------------------------------
MOVE AC,[<code>,,ADR]
TMPCOR AC,
<error return>

ADR: <filename>,,0
IOWD BLEN,BUF

BUF: BLOCK BLEN

Code Function

0 Return in AC the number of words of free TMPCOR space.
1 Read specified file.
2 Read and delete specified file.
3 Write specified file (deleting old version, if any).
4 Read TMPCOR directory.
5 Read and clear TMPCOR directory.

The TMPCOR UUO allows a job to leave several short files in core from
the running of one program to the next. A RESET will not affect
these files, which can be referenced only by the job that created
them. All of a job's TMPCOR files are deleted when the job is
killed. This system of temporary storage improves response times by
reducing the number of disk operations. A TMPCOR file must be
written or read all in one dump-mode operation¬you cannot pick up
reading or writing where you left off; however, when reading a
temporary file, you do not have to read the entire file. The sum of
the sizes of all the TMPCOR files for a single job is not allowed to
exceed 400 words.

Each TMPCOR file has an EXPLICIT three-character sixbit file name and
an IMPLICIT project-programmer name (PPN). When you create a
temporary file, the file is given your current ALIAS (Disk PPN) as
its project-programmer name. To reference the file later, either to
read, delete or overwrite it or to find it in a TMPCOR directory,
your ALIAS must be equal to the file's PPN (i.e., your ALIAS when the
file was written).

For the TMPCOR UUO, AC left should contain a code that indicates
which one of several functions is to be performed. AC right should
hold the address of a two-word block which contains, as indicated
above, the name of the file being referenced (if any) and the length
(BLEN) and location (BUF) of the user buffer area from which or into
which data is to written or read. When this UUO returns, AC will
contain a value that depends on the function executed. This UUO
11. Misc. UUOs Misc. UUOs 144

skips on successful completion of the function and takes the direct
(error) return otherwise. Each function is described separately
below.

CODE FUNCTION

0 Get free TMPCOR space. The number of remaining words
of TMPCOR space available to the job is returned in AC.
This function always takes the skip return. (The
two-word block at ADR is not referenced by this
function.)

1 Read file. If the specified file exists, as much of it
as possible is read into the user's buffer area (at
BUF), the length of the file is returned in AC and the
skip return is taken. If the file does not exist, the
number of words of free TMPCOR space is returned in AC
and the direct (error) return is taken.

2 Read and delete file. This function is the same as
function 1 except that the file is deleted after it is
read.

3 Write file. If a file already exists with the
specified name, it is deleted. Next, if there is
enough TMPCOR space for the new file (whose size is
given by BLEN), then the file is written (with the data
at BUF), the number of remaining free TMPCOR words is
returned in AC and the skip return is taken. If there
is not enough space to write the file completely, then
the file is not written, the number of remaining free
TMPCOR words is returned in AC and the direct (error)
return is taken.

4 Read directory. The number of different TMPCOR files
the job has is returned in AC and an entry in the
user's buffer area is made for each file until either
there is no more space or all the files have been
listed. The entry for a file has the following format:

where <name> is the filename and <size> is the file
length in words. This function always takes the skip
return.

5 Read and clear directory. This function is the same as
function 4 except that after the directory is read, all
of the user's TMPCOR files are deleted.
11. Misc. UUOs Misc. UUOs 145

UUOSIM [OP=047, ADR=400106] CALLI 400106
--------------------------------------------------
MOVEI AC,ADR
UUOSIM AC,

ADR: <PC saved here for normal UUOs>
<UUO saved here for normal UUOs>
<PC to transfer to for normal UUOs>
ADR+3: <PC saved here for I-level UUOs>
<UUO saved here for I-level UUOs>
<PC to transfer to for I-level UUOs>
ADR+6: <PC saved here for spacewar UUOs>
<UUO saved here for spacewar UUOs>
<PC to transfer to for spacewar UUOs>

The UUOSIM UUO allows a user to have all UUOs trap to certain
locations in his core image instead of being executed by the system.
At the same time the user can still have the system execute whatever
UUOs the user needs. The UUOSIM UUO passes to the system the address
of a 9-word block which consists of three contiguous 3-word blocks,
each specifying what the system should do when a certain kind of UUO
is given. The first 3-word block indicates what should be done on
UUOs given by the user's main program; the second 3-word block
pertains to UUOs given at interrupt level; the third block is for
UUOs given at spacewar level on the PDP-10. (Note that UUOs can
NEVER be executed on the PDP-6.) The address of the 9-word block
should be in the AC specified in the UUOSIM UUO. After this UUO is
executed, subsequent UUOs will cause the following action, using the
appropriate 3-word block as mentioned above.

If the second word of the block is non-zero or if the third word is
zero, then the UUO is executed by the system in the usual manner.
Otherwise, the PC at the time the UUO was encountered is saved in the
first word of the block, the UUO itself is stored in the second word
of the block and control is transferred to the PC specified in the
third word of the block. Note that the PC stored in the first word
has already been incremented; it points to the instruction
immediately following the UUO. Note also that the UUO stored in the
second word has already had the effective address calculation carried
out; the effective address is in the address field and the indirect
and index fields will be zero. The prior test for the second word
being non-zero has the effect of disabling user handling of UUOs
issued by the user's UUO handler itself.

To undo the above effect of the UUOSIM UUO, give the UUOSIM UUO with
zero in the specified AC and with ADR+1 (from the original UUOSIM
given) containing a non-zero value so that this UUO will not simply
be handed back to you. The RESET UUO (see page 139) will also
11. Misc. UUOs Misc. UUOs 146

disable further special user handling of system UUOs (but again you
must force the system to handle the RESET itself).

WAKEME [OP=047, ADR=400061] CALLI 400061
--------------------------------------------------
MOVEI AC,ADR
WAKEME AC,
<error return>

ADR: <phantom's jobname in sixbit>
<phantom's PPN in sixbit>
<data>

data < 0 means never start this job
data = 0 means start this job now if it is not already running
data > 0 means start this job at the time specified by <data>,
where <data> = <date>,,<time in minutes>

The WAKEME UUO is used to start up, or prevent from starting up, any
of the system phantom jobs. A phantom is a job started by the system
to do some system-related work but which runs as a user job. Phantom
jobs are defined by the fact that they run with the JLOG bit off in
the job status word (see the JBTSTS UUO on page 101) and are not
logged in under the project-programmer name 100,100. The JLOG bit
being off means that the job will go away if it hits an error (such
as a parity error or illegal memory reference). Also, if you type a
monitor command to a job with the JLOG bit off, the job will go away
immediately.

For this UUO, AC should contain the address of a three word block.
The first two words of this block should have, in sixbit, the name of
the phantom to be started up and the project-programmer name where
that phantom lives. The third word of the block should contain a
code indicating what the system should do about the phantom. A
negative code indicates that the phantom should never get started up,
a zero code means that the phantom should be started now unless it is
already running, and a positive code represents a date (left half)
and time (right half) when the phantom should be started up. The
date is in system date format (see the DATE UUO on page 95) and the
time is in minutes after midnight.

If there is no phantom with the jobname and PPN given, the error
return is taken. Otherwise, the skip return is taken.

N.B. You should not use this UUO unless you are the person
responsible for the phantom you are referencing or unless you are
absolutely sure that what you are doing is okay.
11. Misc. UUOs Misc. UUOs 147

JOBRD [OP=047, ADR=400050] CALLI 400050
--------------------------------------------------
MOVEI AC,ADR
JOBRD AC,
<error return - code in ADR+1>

ADR: <job name or number>
-<word count>,,<address of data in his core image>
<address in your core image where data is to go>

Error codes: 1 non-existent job number (job number = 0)
2 ambiguous job name
3 non-existent job name (or job number > 77)
4 address out of bounds (either in your
core image or in his)
5 job not logged in
6 block too large (more than 1K)

The JOBRD UUO allows you to read a block of data out of the core
image of another job. The data is BLTed from his core image to
yours. AC should contain the address of a three word block, the
first word of which should contain either the sixbit name or the
number of the job whose data you wish to copy. The left half of the
second word should contain the negated count of the number of words
to be read; the right half of the second word should contain the
address of the block in the other job that you want to copy. The
third word should contain the address in your core image where you
want the data to be put. The maximum size block that can be read
using this UUO is 1K (=1024 words).

If this UUO fails for any reason, the direct (error) return is taken
and a code indicating the cause of failure is placed in ADR+1. A
list of the possible error conditions and their codes is given above.
If this UUO succeeds in transferring the data, the skip return is
taken.

LOCK [OP=047, ADR=400076] CALLI 400076
--------------------------------------------------
LOCK AC,

The LOCK UUO is used to lock your job in core so that you can be sure
that you will not be either swapped out or shuffled in core. Upon
return from this UUO, you will have been locked in core and AC will
contain your job's protection-relocation constant. Your protection
constant (in the left half of AC) is the highest address in your core
11. Misc. UUOs Misc. UUOs 148

image and always ends in 1777. The relocation constant (in the right
half of AC) is the value that is added to each memory address you
reference, in order to get the real memory address of the desired
word in your core image.

Jobs with upper segments are not allowed to lock themselves in core.

To undo the effect of the LOCK UUO, you can use the UNLOCK UUO (see
below) or the RESET UUO (see page 139). Any system-detected error
condition will also cause an UNLOCK to be done, as will any attempt
to change your core size with the CORE UUO (see page 97). The LOCK
UUO itself will first do an UNLOCK before locking you in.

The LOCK UUO should be used only when really necessary. When users
are locked in core, there is less core available for normal users who
are being swapped in and out; and when there are or have recently
been two or more users locked in core, there is the possibility of
having a hole in core that cannot be used (except for other locked
jobs). A job that must remain locked in core for some time should
give the LOCK UUO over again whenever there is a chance to do so
because this causes the job first to be unlocked, then shuffled to
fill any hole and finally locked again.

UNLOCK [OP=047, ADR=400077] CALLI 400077
--------------------------------------------------
UNLOCK

The UNLOCK UUO is used to unlock your job from core after you have
used the LOCK UUO (see above) to lock it. Many other things also
cause an UNLOCK to be done. These are listed under the LOCK UUO
above.

SETDDT [OP=047, ADR=2] CALLI 2
--------------------------------------------------
MOVEI AC,<address of DDT or RAID>
SETDDT AC,

The SETDDT UUO is used to tell the system the starting address of DDT
or RAID in your core image. This address is saved in JOBDDT in your
job data area (see Appendix 4); however, you are not allowed to
change this value directly--you must use this UUO instead. The DDT
monitor command starts your program at the address contained in
JOBDDT if that address is non-zero.
11. Misc. UUOs Misc. UUOs 149

SPWBUT [OP=047, ADR=400000] CALLI 400000
--------------------------------------------------
SPWBUT AC,

The SPWBUT UUO returns in the AC the value of the spacewar buttons.
Each spacewar button controls one bit in this value. The bit is a
one if the circuit represented by that bit is open and a zero if the
circuit is closed. Only bits 22:26 and 28:35 (the 0,,37377 bits) are
currently wired up. If the buttons are unplugged, the wired-up bits
will all be on (value of 0,,37377).

The regular spacewar buttons only utilize the low-order 8 bits (bits
28:35--the 0,,377 bits). At the time of this writing, these buttons
use normally-closed switches (bit values of zero) except that the
switch for bit 34 (the 0,,2 bit) is normally open (bit value of one).
This means that with the buttons plugged in and not depressed, the
value of the spacewar buttons is 0,,37002. No claim is made,
however, that new buttons will not replace those that are described
in this paragraph. To be sure what kind of switches are in the
buttons, find and examine the buttons yourself.

EIOTM [OP=047, ADR=400005] CALLI 400005
--------------------------------------------------
EIOTM

The EIOTM UUO puts you into IOT-USER mode, in which opcodes from 700
up are executed as machine I/O instructions rather than as UUOs.
This mode is described further in Appendix 3.
12. Obsolete UUOs Obsolete UUOs 150

SECTION 12

OBSOLETE OR OTHERWISE USELESS UUOS

This section documents some UUOs that still work but which, for
various reasons, are obsolete. Mentioned at the end of this section
are some other UUOs that are ever more obsolete in that they do not
work. In general, there are better ways to do the things all of
these UUOs do, but the documentation is included for completeness and
for the benefit of people trying to decode rusty old programs which
use these UUOs. Users are to be discouraged from using these in any
new pieces of code.

12.1 Old UUOs

Here are some UUOs that still work although they are generally
unnecessary.

INTIIP [OP=047, ADR=400031] CALLI 400031
--------------------------------------------------
INTIIP AC,

The INTIIP UUO is designed to be given by a process running at
interrupt level. It returns in AC the bit representing the source of
the current interrupt. This is a copy of the value of JOBCNI at the
time your interrupt-level routine is started up. Thus it is much
more efficient to do a MOVE AC,JOBCNI and the results are the same.
If you give this UUO when you are not at interrupt level, then zero
is returned in AC.

USKIP [OP=047, ADR=400041] CALLI 400041
--------------------------------------------------
USKIP
<return if no UUO in progress>

The USKIP UUO can be used by an interrupt-level process to determine
if the interrupted program was in the middle of executing a UUO.
12.1 Old UUOs Obsolete UUOs 151

USKIP will skip if there was a UUO in progress at the time the
interrupt occurred and will take the direct return if no UUO was
being executed. Thus this UUO will tell you whether a UWAIT will
return immediately. The same information can be obtained by
examining the user-mode bit (bit 5--the 10000,,0 bit) in JOBTPC; the
user-mode bit will be on unless a UUO was in progress.

The USKIP UUO is illegal except at interrupt level.

LIOTM [OP=047, ADR=400006] CALLI 400006
--------------------------------------------------
LIOTM

The LIOTM UUO gets you out of IOT-USER mode, thus making opcodes over
700 into UUOs again. However, this function can be achieved without
doing a UUO at all. For instance, the instruction
JRST 2,@[.+1]
will also get you out of IOT-USER mode. See the writeup of IOT-USER
mode in Appendix 3.

RUNMSK [OP=047, ADR=400046] CALLI 400046
--------------------------------------------------
MOVEI AC,<processor enable bits>
RUNMSK AC,

The RUNMSK UUO is intended to allow you to select which processor
(the PDP-10 or the PDP-6) should run your job. However, the PDP-6 is
not capable of running jobs; thus this UUO is useless.

DDTIN [OP=047, ADR=1] CALLI 1
--------------------------------------------------
MOVEI AC,ADR
DDTIN AC,

ADR: <21 word block for returned characters>

The DDTIN UUO is used to read in all characters that have been typed
on the terminal attached to your job. This UUO does not wait for any
special activation character; it just reads whatever is in the TTY
input buffer and returns those characters in the block pointed to by
12.1 Old UUOs Obsolete UUOs 152

the contents of AC. This block should be at least 21 words long in
order to hold all the characters being read; at most =84 characters
will be read. The characters are returned as an ASCIZ string at ADR
(7 bits per character, 5 characters per word, with a null (zero) byte
after the last character read).

If the TTY input buffer is empty, this UUO will not return until a
character is typed. Thus at least one character is returned each
time this UUO is given.

TTYUUO (see Section 3.3) provides generally more convenient ways of
reading characters from the terminal.

DDTOUT [OP=047, ADR=3] CALLI 3
--------------------------------------------------
MOVEI AC,ADR
DDTOUT AC,

ADR: <ASCIZ string to be typed out>

The DDTOUT UUO types out an ASCIZ string on the terminal. AC should
contain the address of the first word of the string. The string is
terminated by the first null (zero) byte. The OUTSTR UUO (see page
44) is the recommended way of typing out strings although this UUO
still works.

GETCHR [OP=047, ADR=6] CALLI 6
--------------------------------------------------
MOVE AC,[<device name in sixbit, or channel number>]
GETCHR AC,

The GETCHR UUO does exactly the same thing as the DEVCHR UUO; see
page 38.
12.1 Old UUOs Obsolete UUOs 153

SETNAM [OP=047, ADR=400002] CALLI 400002
--------------------------------------------------
MOVE AC,[<sixbit job name>]
SETNAM AC,

The SETNAM UUO is used to change your job name to that given in the
AC. Any job name is legal. This UUO does exactly the same thing as
the SETNAM UUO which is CALLI 43.

SEGSIZ [OP=047, ADR=400022] CALLI 400022
--------------------------------------------------
SEGSIZ AC,

The SEGSIZ UUO returns in AC the size of your upper segment. The
size returned is the protection constant of your segment, i.e., the
number of words in it minus one. If you have no upper segment
attached, zero is returned.

This segment size can be found out more easily by looking at JOBHRL
in the job data area (see Appendix 4).

12.2 Privileged UUOs

The UUOs listed below are privileged UUOs designed for use only by
the LOGIN and LOGOUT programs.

12.3 Useless UUOs

Each of the following unimplemented UUOs is either illegal or a
no-op.

DDTGT [OP=047, ADR=5] CALLI 5
DDTRL [OP=047, ADR=7] CALLI 7
TRPSET [OP=047, ADR=25] CALLI 25
TRPJEN [OP=047, ADR=26] CALLI 26
GETSEG [OP=047, ADR=40] CALLI 40
GETTAB [OP=047, ADR=41] CALLI 41
12.3 Useless UUOs Obsolete UUOs 154

SPY [OP=047, ADR=42] CALLI 42
GDPTIM [OP=047, ADR=400065] CALLI 400065
XPARMS [OP=047, ADR=400103] CALLI 400103
[OP=042]
[OP=044]
[OP=045]
[OP=046]
[OP=052]
[OP=053]
[OP=054]
[OP=700]
13. I/O Devices I/O Devices 155

SECTION 13

INDIVIDUAL DEVICE DESCRIPTIONS

This section reveals the idiosyncrasies of each of the various I/O
devices and of the system in handling these devices. Each device is
described in a separate subsection. For features common to all (or
most) of these devices, consult Section 2. For the common bits in
the device I/O status word, see specifically Section 2.6.

13.1 The Disk

Disk storage is organized by files. Each file is allocated one or
more disk tracks depending on the size of the file. Each track is
2.25K words long and consists of =18 records of =128 (200 octal)
words each. All disk activity is in terms of whole records. In
buffered mode, this means that exactly 200 words of data are
transferred for each buffer, regardless of the actual buffer size;
thus using a non-standard size buffer for disk I/O should not be
attempted. In dump mode an output command to write a number of words
that is not a multiple of 200 will cause the last record written by
the command to be filled with zeroes. These zeroes will not be
included in the word count for the file if and only if they are part
of the last record in the file.

WARNING: With a dump mode output command indicating an ODD number of
words, the low order 4 bits (the 0,,17 bits) of the last word will be
written out as zero regardless of their actual values. Thus to
ensure that a dump mode output does not lose any data, you should
make sure either that there are an even number of words in the
transfer or that the last 4 bits of the last word do not hold any
significant data (for instance you can add a zero word after the last
normal data word).

In buffered mode, disk I/O is optimized to account for track
boundaries. On output, this means that filled buffers will not
actually get written out until there is only one empty buffer left or
until enough buffers have been filled to finish out a whole track.
On input, as much of a whole track as will fit into your buffers is
transferred all at one time.

Each file belongs to some project-programmer name (PPN). The
directory of all files of a particular PPN exists as a file 1) whose
13.1 The Disk I/O Devices 156

name is given by the sixbit PPN word (project right-justified in the
left half, programmer name right-justified in the right half),
2) whose extension is .UFD and 3) whose own PPN is [1,1]. Thus the
file FOOBAZ.UFD[1,1] is the directory for the disk area [FOO,BAZ].
The directory for the disk area [1,1] is the file " 1 1.UFD[1,1]",
which contains the names of, and pointers to, all the directory
files.

Each directory file consists of a number of 4-word entries, each of
which either points to a file or is unused. These 4-word entries
have the following format:

The first three words are exactly the first three words you get back
from a successful LOOKUP (see page 24). The <file name> of an entry
not in use is zero.

Long Block LOOKUPs, ENTERs and RENAMEs

If the 0,,400 bit (bit 27) is on in the device status word when you
give a LOOKUP, ENTER or RENAME UUO for the disk, then the UUO uses a
6-word block rather than the usual 4-word block (see these UUOs
starting on page 24). An ENTER using the 6-word block will set the
file's date and time written directly from the third word of the
block rather than from the current time and date.

The fifth word of the block is supposed to hold the date and time the
file was last referenced, in the same format as the date and time
written; however, after setting up this word when the file is
created, the system never updates it. The sixth word of the block
contains the date the file was last dumped on magnetic tape for disk
backup. The format of this word is as follows:

BITS OCTAL MEANINGS OF FIELDS IN DUMP-DATE WORD

4 20000,,0 This bit is a one if this dump-date word
is invalid.

24:35 0,,7777 This is the date last dumped, in system
date format (see the DATE UUO on page
95).
13.1 The Disk I/O Devices 157

0 400000,,0 This bit is a one if the file was last
dumped on a temporary class dump. This
bit is zero if the dump was of system
permanent class.

9:20 777,,700000 These bits hold the number of the tape
on which the file was last dumped.

1:3 340000,,0 These bits hold the number of times this
file has been dumped in permanent class
dumps.

Record Offset

In the normal case, the data in a disk file starts in the first
record of the first track allocated to the file. However, it is
sometimes convenient to use the first few records of a file to store
special data which is associated with the file but which is not
really part of the file. To this end, the record offset feature was
added to the disk system. This feature allows a user to HIDE any
number of records at the beginning of a file simply by specifying the
physical record number of the first record of the normal part of the
file. When this is done, any program doing normal disk I/O with this
file will never see the hidden records; however, any programs that
need to access the hidden part can do so easily.

In a disk file, logical record number 1 is the first record of the
normal part of the file. The last hidden record is logical record
number 0, and preceding records are given successive negative
numbers. Thus, in a file with N hidden records, the first physical
record of the file would be logical record number -N+1, the remaining
hidden records would be numbered, -N+2, -N+3, ..., -1, and 0. The
first logical record of such a file would be physical record number
N+1.

To access the hidden records (which come before logical record 1),
use the USETI and USETO UUOs (see Section 2.13) with the appropriate
logical record number. Note that in these UUOs the effective address
is interpreted as a signed twos-complement number which specifies the
logical record number of interest.

To set the record offset for a file, a special form of the MTAPE UUO
for the disk is used. MTAPE for disk has several uses; you indicate
the one you want by specifying a function number along with the MTAPE
UUO. The function number for the set-offset UUO is 21. Another
MTAPE (function number 20) can be used to retrieve the current value
13.1 The Disk I/O Devices 158

of the record offset. In both cases the actual offset number used is
the PHYSICAL RECORD NUMBER OF THE FIRST LOGICAL RECORD of the file,
i.e., the number of hidden records plus one. The get-offset and
set-offset UUOs are described in detail below in the MTAPE writeup;
see MTAPEs with function numbers 20 and 21.

Disk I/O Status Word Summary

BITS OCTAL NAME MEANING OF A 1

27 0,,400 DMPBIT Use 6-word blocks in LOOKUP,
ENTER and RENAME.

28 0,,200 GARBIT Suppress error message when
disk is full or bad retrieval
from LOOKUP, ENTER or RENAME;
take error return instead.
13.1 The Disk I/O Devices 159

MTAPE UUOs for the Disk

MTAPE [OP=072]
--------------------------------------------------
MTAPE <channel number>,ADR ;MTAPE form for the DISK

ADR: SIXBIT /GODMOD/
<function number>
<other arguments depending on function>
...

This form of the MTAPE UUO is used to do special things with the
disk. The exact meaning of this UUO depends on the function number
in ADR+1. Some of the functions are explained below along with
descriptions of what the block at ADR should contain when the UUO is
called for that function. If you need to know about any of the
functions not mentioned here, see a systems programmer.

To do any of the following functions, you must have INITed or OPENed
the disk on the channel indicated by the AC field of the UUO; some of
these functions also require that a file be open on this channel.
Finally, some functions take the skip return on success and the
direct return on errors; other functions always take the direct
return. See the writeups below for details.

--------------------------------------------------
ADR: SIXBIT /GODMOD/ ;GET USET POINTER
0

Function 0 for a disk MTAPE gives you the current value of the USET
pointer for the file open on this channel. This is the value which
can be set by a USETI, USETO or UGETF UUO (see Section 2.13). The
pointer is returned in ADR+1 (where the 0 was).
13.1 The Disk I/O Devices 160

--------------------------------------------------
ADR: SIXBIT /GODMOD/ ;INCLUDE RECORD IN FILE
16 ;This function takes skip return on success.
<record number>

Function 16 for a disk MTAPE allows you to include an existing record
in the word count for a file. This is useful if you have managed to
write out some data to extend a file but the file was never closed
(system crash, etc.). The number of the last record you wish added
to the file should be in ADR+2. If this function is successful, the
skip return is taken and the USET pointer for the file is left
pointing to the indicated record with IODEND (end of file flag)
cleared. (If the record specified is not beyond the end of the file,
the only result will be to have changed the USET pointer and to have
cleared IODEND, and the skip return will be taken.) If there is no
file open on this channel, or if the record you specified does not
exist, the direct (error) return is taken.

--------------------------------------------------
ADR: SIXBIT /GODMOD/ ;UPDATE RETRIEVAL
17

Function 17 for a disk MTAPE forces all pointers and header
information for the file being written on this channel to be updated.
This is mainly useful when extending a file in Read-Alter mode.
After this function has been executed, all the data written into the
file is included in the retrieval. So if the system crashes, the
word count for the file will be up to date.

--------------------------------------------------
ADR: SIXBIT /GODMOD/ ;GET RECORD OFFSET
20
<record number returned here>
<physical file length returned here>

Function 20 for a disk MTAPE returns the physical record number of
the first logical record of the file open on this channel. This
record number is returned at ADR+2; the physical length of the file,
including any hidden records, is returned at ADR+3. See the section
above on the record offset feature.
13.1 The Disk I/O Devices 161

--------------------------------------------------
ADR: SIXBIT /GODMOD/ ;SET RECORD OFFSET
21
<physical record number of first logical record>

Function 21 for a disk MTAPE is used to set the record offset for the
file open on this channel. The physical record number of the record
which is henceforth to be considered the first logical record of the
file should be in the specified at ADR+2. If this function succeeds,
the skip return is taken. If there is no file open on this channel,
or if some other error occurs, then the direct (error) return is
taken. See the section above on the disk file record offset feature.
13.2 Terminals I/O Devices 162

13.2 Terminals

Here are the meanings of some of the bits in the TTY I/O status word.
13.2 Terminals I/O Devices 163

BITS OCTAL NAME MEANINGS OF 1'S IN TTY I/O
STATUS WORD

9 400,,0 TPMON The terminal is in monitor
mode. This bit is usually
turned off when your job is
running, but you can make it
stay on by giving a CSTART or
CCONTINUE monitor command.
When this bit is on, your
program will not be able to
get any input from the
terminal because all the
characters will be going to
the monitor's command decoder.

26 0,,1000 IOSUPR Control-O ([ESCAPE] O on
displays) has been typed.
When this bit is on, nothing
your program outputs to the
terminal will be typed out.
You can clear this bit by
doing any TTY input operation
or by re-initializing the TTY
with an INIT or an OPEN. On
teletypes, a second control-O
will clear this bit as will
[BREAK] O on displays.

27 0,,400 NOECHB Characters typed to the
program running on this
terminal will not have any
control bits (CONTROL or META)
echoed. Control bits are
always echoed when the TTY is
in monitor mode (TPMON bit
on--see above). The NOECHB
bit can be turned on and off
only by the INIT and SETSTS
UUOs, except that a RESET (see
page 139) will clear this bit,
thus turning echoing of
control bits back on.

28 0,,200 NOECHO Characters typed to the
program running on this
terminal will not be echoed to
the terminal by the monitor;
13.2 Terminals I/O Devices 164

see Section 3.1. This bit can
only be turned on by UUO. A
RESET (see page 139 will clear
this bit, thus turning echoing
back on.
13.3 The Line Printer I/O Devices 165

13.3 The Line Printer

The line printer (LPT) has its own character set which differs
slightly from the system ascii character set (see Appendix 7).
Because of this, the system normally does character conversion to
insure that what you get is what you want.

In addition, there are several extra characters on the line printer
that have no ascii representation. To get one of these characters on
the line printer, you send a 177 character followed by the
appropriate code from the table below.

CODE CHARACTER

000 Center dot. (A period moved up to center it.)
011 Gamma.
012 Small delta.
013 Integral sign.
014 Plus-or-minus sign.
015 Circle-plus sign.
020 Skip to top of double form.
021 Space down 1 line; write over page boundary.
022 Space down 3 lines.
023 Space down to next 1/2 page boundary.
024 Space down to next 1/6 page boundary.
177 Backslash.

Line printer paper has =66 lines/page but the LPT usually skips to
the top of form after =54 lines. This automatic page ejection can be
overridden by use of the '177&'21 character in place of linefeeds.

If you initialize the line printer with the 100 bit (bit 32) on in
the mode (I/O status word), then the conversion from system ascii to
line printer codes is inhibited. In this mode, you get the following
differences in characters:

CODE MODE 0 CHARACTER MODE 100 CHARACTER

030 _ (underline) ← (left arrow)
032 ~ (tilde) ↑ (up arrow)
100 @ (at sign) ' (right quote)
134 \ (backslash) } (close brace)
136 ↑ (up arrow) circumflex
137 ← (left arrow) → (right arrow)
140 ` (left quote) @ (at sign)
174 | (vertical bar) \ (backslash)
176 } (close brace) | (vertical bar)
13.3 The Line Printer I/O Devices 166

Finally, under normal circumstances, if the line printer runs out of
paper, gets jammed, or suffers some other physical ailment, you will
get a system error message from which point you can CONTINUE after
correcting the situation. If, however, you initialize the line
printer with the 200 bit (bit 31) on in the mode (I/O status word),
then when the LPT is ill an error bit will be turned on in the LPT
status word and the error return will be taken by any OUTPUT UUO you
try; no error message will be printed.

LPT I/O Status Word Summary

BITS OCTAL NAME MEANING OF A 1

28 0,,200 HNGTRP No error message on hung
device (see above).

29 0,,100 LPTNCC No character conversion (see
above).
13.4 The XGP I/O Devices 167

13.4 The XGP

The Xerox Graphics Printer (XGP) provides a means of making a
hardcopy listing of virtually any drawing that can be expressed as a
one-bit raster. The XGP accepts as data a bit array describing each
scan line that is printed. Each scan line is approximately 1700
bits; scan lines are spaced at about 200 per inch along the paper. A
picture is built by sending successive scan lines to the XGP. (The
number of bits per scan line and the number of scan lines per inch
are adjustable on the XGP and hence are not necessarily constants.)

There are presently two distinct modes of operating the XGP: video
mode and character mode.

Video Mode

In video mode, 36-bit words are interpreted as video data. Words are
grouped together into portions of a scan line by the use of a Group
Command Word (GCW). The GCW precedes the data portion of the group
and specifies how many words of video data are to be found in this
group. Also the GCW allows the video data to be positioned anywhere
along the scan line. The exact format of the GCW is given below.

BITS OCTAL NAME VALUES OF FIELDS IN GCW

0 400000,,0 MARK If this bit is a 1, then after
the data is sent the paper
will be marked for cutting.
Paper cutting is not exact so
a MARK should be preceded and
followed by several blank
lines.

1:11 377700,,0 LNSKIP The paper will be advanced by
LNSKIP blank lines before
printing. LNSKIP = 1 is used
for normal, single spacing.
LNSKIP = 0 prevents any
advance to the next scan line
and prints on the same line as
the last group.

12:23 77,,770000 COLSKP The column register in the XGP
interface will be set to
COLSKP before the data is
13.4 The XGP I/O Devices 168

transmitted. This means that
the first data bit in this
group will appear in this
column.

24:29 0,,7700 unused This field has no meaning
currently. It should be set
to zero to avoid confusion in
case some meaning is attached
to it in the future.

30:35 0,,77 DWCNT DWCNT words following the GCW
will be transmitted to the XGP
as video data (for each bit, 0
means white, 1 black). The
word following those DWCNT
words is then taken to be
another GCW. If DWCNT = 0
then there are no data words
in this group and the next
word is another GCW.

Modes 17 and 117 are used for video data. These modes accept the
format that is described above.

In mode 17, the effective address of the OUTPUT UUO points to a
standard dump mode command list. The command list specifies the data
to send to the XGP. Each OUTPUT will wait until the entire command
list is processed before returning to the user. The paper will be
cut at the completion of each command list.

Mode 117 is like mode 17 except that the OUTPUT UUO returns to the
user while data is being sent to the XGP. In this mode the user can
overlap the input of one data block with the output of another.
Three data blocks are needed in this mode: one being emptied by the
XGP, another pending, and another being filled by the user program.
The first two OUTPUT UUOs will return immediately (having established
the current and pending output blocks). After the user fills his
third block and gives an OUTPUT UUO he will be forced to wait until
the current block is empty (at which time the pending block becomes
current and the block specified in this OUTPUT will become the new
pending block). When the third OUTPUT returns, the first block will
be free to use. In video mode the XGP requires up to 10,000 words of
data per second. Care should be exercised in programming to always
have data ready for the XGP.

Another requirement of mode 117 is that the command lists that point
to the three data blocks must be disjoint. The actual requirement is
that the command list for each block must be valid while the block is
13.4 The XGP I/O Devices 169

being output. In particular, don't use the same physical location in
your program for more than one command list.

In mode 117 you must do a CLOSE UUO after the last OUTPUT to force
the transmission of all buffers to the XGP. It is possible that a
user program may not be able to supply data fast enough in mode 117.
In this event, the paper will be cut wherever the data runs out. A
status bit, (bit 25--the 0,,2000 bit, IOTEND), is provided which
warns the program that this has occurred. This bit is set only in
mode 117 when the data runs out and no CLOSE has been done.

Character Mode

In character mode, the XGP can be used to print text using one or
more fonts and to draw vectors. Modes 0 and 13 are the character
modes for the XGP. In these modes, each 36-bit word is interpreted
as five 7-bit bytes. There is no fixed mapping between byte values
and particular graphic symbols. The graphic symbol for any byte is
defined by the current font in use. Certain byte values have special
meanings consistent with ascii, and one byte value, octal 177, is
used as an escape which gives the bytes that follow a special
meaning.

Character mode permits vectors and multiple active text lines. The
7-bit bytes taken from the user's buffer are interpreted as follows:

Byte Value Usual meaning Escape meaning

0 Null -- byte is ignored Normal
1 Normal XGP ESCAPE 1
2 Normal XGP ESCAPE 2
3 Normal XGP ESCAPE 3
4 Normal XGP ESCAPE 4
5:10 Normal Reserved
11 TAB Normal
12 LF Normal
13 Normal Reserved
14 FF Normal
15 CR Normal
16:37 Normal Reserved
40:176 Normal Normal
177 ESCAPE Normal

NORMAL means that the definition of this byte in the current font
will be printed. If this byte is undefined in the current font, it
will be ignored.
13.4 The XGP I/O Devices 170

ESCAPE means that the next byte will have an alternate meaning
selected from the column ESCAPE MEANING.

TAB produces a column select to the first column which is at least
the width of a blank to the right of the current column position, and
some multiple of 8 blank widths to the right of the left margin.

LF activates the current text line. The current text will be queued
to be printed. The default Y-position of text will be advanced by
the number of scan lines it takes to draw this line, plus the number
of scan lines specified by the interline space argument to the margin
set function of the XGP MTAPE UUO (see page 173). This default
Y-position will be used for the next text line (unless changed by a
vector command or ESCAPE 3).

FF, like LF, activates the text. In addition, FF causes a page eject
after the current text line is printed. FF also sets the default
Y-position to the first line below the top of page margin on the new
page.

CR causes a column select to the current left margin to be generated.

XGP ESCAPE 1 ('177&'001) causes the next 7-bit byte to be read as a
special operation code. The following codes are implemented:

CODE XGP ESCAPE 1 MEANING

0:17 Font select. The code, 0 to 17, is taken as the font
identification number of the font to be used.

20:37 Reserved for future use.

40 Column select. The next 14 bits (2 bytes) are taken
modulo =4096 as the X-position to print at next. (The
intention is to allow arbitrary-width spaces for text
justification.)

41 Underscore. The next 7-bit byte is taken in two's
complement as the relative number of the scan line on
which the underscore is to occur, where zero
represents the baseline of the text, negative values
represent lines above the baseline and positive values
lines below it. The next 14 bits (2 bytes) are taken
modulo =4096 as the length of the underscore. (If the
underscore command is the first thing on a line, the
baseline will be set to the baseline of the current
font.)

42 Line space. This does a linefeed and then takes the
next byte as the number of blank scan lines to insert.
13.4 The XGP I/O Devices 171

43 Base-line adjust. The next 7 bits are taken in two's
complement as the base-line adjustment to the current
font. The adjustment sticks until reset by another
adjust command or a font select. The intention is to
allow a font to be used for subscripts and
superscripts. (Increment baseline for superscript,
decrement for subscript. Values 0:77 are increments;
100:177 are decrements: 100 means -100, 177 means -1.)

44 Print the paper page number. The paper page number is
set to 1 by a form feed. It is incremented each time
the paper is cut. The decimal value of this count is
printed.

45 Accept heading text. The next byte is a count of
bytes to follow. Those bytes will be read into the
heading line. When that count is exhausted, the
heading line will be printed. When a linefeed or line
space command is given that would cause text to be
printed below the current text area, a form feed is
inserted by the XGP and if a heading is defined, it
will be printed.

46 Start underline. Set the left end of an underline.
See the stop underline command below.

47 Stop underline. The next byte is the scan line on
which to write the underline (same as in XGP
Underscore, 41 above). The extent of the underscore
is defined by this command and the start underline
command. If this command is not preceded by a start
underline command, the results will be unpredictable.
No underline will happen until this command is given.
Beware of column selects.

XGP ESCAPE 2 ('177&'002) causes the next 7-bit byte to be taken as a
twos-complement column increment. Values 0:77 are positive
increments; 100:177 are negative increments: 100 means -100, 177
means -1.

XGP ESCAPE 3 ('177&'003) causes the next 2 bytes to be taken as the
scan line number on which to start this text line. Scan line 0 is
the first scan line on the page (immediately following the cut). The
topmost scan line of the present text line will be placed on the scan
line indicated in this command. If there is no current text line,
the next text line will be put there.
13.4 The XGP I/O Devices 172

XGP ESCAPE 4 ('177&'004). This escape is used to specify a vector.
It is followed by =11 bytes describing the vector:

2 bytes of Y0 Scan line number of first line of vector.
2 bytes of X0 Column position of left edge of first line of
the vector.
3 bytes of DX Delta X. 1 bit of sign; 11 bits of integer; 9
bits of fraction.
2 bytes of N The number of scan lines on which this vector
is visible.
2 bytes of W The column width of each scan line.

The XGP service must be presented with vectors sorted by ascending
values of Y0. If the vectors are not sorted, the output will be
wrong.

The escape significances of codes 5 through 10, 13, and 16 through 37
are not defined at the present time but are reserved for future use.

XGP I/O Status Word Summary

BITS OCTAL NAME MEANING OF A 1

18 0,,400000 IOIMPM Illegal mode, PDP-6 not
responding, or XGP not
responding.

19 0,,200000 IODERR PDP-6 detected error: XGP
reporting something wrong (out
of paper, etc.), buffered mode
data miss, or line too
complex.

20 0,,100000 IODTER Font Compiler lossage.

25 0,,2000 IOTEND Data ran out before CLOSE
given in mode 117.
13.4 The XGP I/O Devices 173

XGP MTAPE UUO

The MTAPE UUO is used to provide extended control and status
reporting of the XGP. MTAPE is not synchronized with the data stream
except that certain MTAPEs imply CLOSE before their operation.

MTAPE [OP=072]
--------------------------------------------------
MTAPE <channel number>,ADR

ADR: <function number>
<other data depending on function number>
...

An MTAPE which specifies a channel on which the XGP is open is
interpreted as follows. The effective address of the MTAPE (ADR)
points to a word containing a function number which determines the
meaning of the UUO. The data at ADR+1 and following depends on the
function selected.

FUNCTION MEANING

0 Return error status.
ADR+1/ Major error code.
ADR+2,3,4/ Error data (see below).

1 Font compile and select.
ADR+1/ Font file name in sixbit.
ADR+2/ Font file name extension.
ADR+3/ PPN of font file.
ADR+4/ Font identification number: 0:17.

Note: This function skips if there is no error.

The font named will be read by the
font compiler. It will be assigned
the font identification number that
is supplied. The identification
number is used only by font select
commands.
13.4 The XGP I/O Devices 174

2 Read margins.
ADR+1/ Top of page margin.
ADR+2/ Page body size.
ADR+3/ Bottom of page margin.
ADR+4/ Left side margin.
ADR+5/ Right side margin.
ADR+6/ Minimum interline space.

3 Set margins.
ADR+1/ Top of page margin; must be ≤ 37777.
ADR+2/ Page body size; must be ≤ 37777.
ADR+3/ Bottom of page margin; must be ≤ 37777.
ADR+4/ Left side margin; must be ≤ 3777.
ADR+5/ Right side margin; ≤ 7777 and > left mar.
ADR+6/ Minimum interline space; must be ≤ 3777.

If the bottom of page margin is
zero, there will not be any paper
cuts. If the page body size is
zero, there will be no paper cuts
except that when a FF (formfeed) is
encountered, the blank space
specified by the bottom of page
margin will be put out and then a
cut will be made.

4 Get status.
ADR+1/ The I/O device status word for the XGP.
ADR+2/ -1 if a data transfer is in progress,
0 otherwise.

5 Pseudo close. Hardly different from CLOSE UUO.
13.4 The XGP I/O Devices 175

6 Set node counts.
ADR+1/ Number of text nodes (default: =16).
ADR+2/ Number of vector nodes (default: =100).

If either node count is zero, the
default value is used for that
count.

The number of nodes needed for text
increases with the complexity of
the text (number of font switches,
etc.). The number of nodes needed
for vectors is related to the
number and size of the vectors.
Generally the default numbers of
nodes is sufficient, and when it is
not, there may not be enough time
for the PDP-6 to do the output
correctly, even if the number of
nodes is increased.

Here are the meanings of the error codes returned from MTAPE function
0.

MAJOR ERROR MEANING

0 No error.

1 Font Compiler lossage: no job slots.

2 Font Compiler lossage: no initial response.

3 Font Compiler lossage: no intermediate response.
13.4 The XGP I/O Devices 176

4 Font Compiler lossage: illegal response.
ADR+2 contains the FC response:
0 Ready.
1 Allocation made.
2 Compilation done.
3 Font compiler error.
ADR+3 contains the error type:
0 Illegal command.
ADR+4 contains the rejected command.
1 Not enough core.
2 LOOKUP Failure.
ADR+4 contains the LOOKUP error code.
3 File error -- unexpected EOF.
4 File error -- character redefined.
5 Disk error.
6 Logical font number too large.
7 File error -- other illegal format.

5 Interrupt-level data missed in buffered mode.

6 XGP hung timeout.

7 Illegal mode.

10 Line too complex. The line compiler ran out
of room while compiling a text line.

11 Out of order. Y0 of a vector or text line is
smaller than the last item (either vector or
text) that was queued. That is, the input
was not properly y-sorted.

12 XGPSER missed. Somehow, the system has
failed to start a vector or text node at the
right place. Possibly there are too many
vectors.

13 Page too long. You started a vector below
the bottom of a page.

14 Illegal vector parameters. A vector you
specified will go off the page.
13.4 The XGP I/O Devices 177

XGPUUO UUO

XGPUUO is of interest only to the Font Compiler. This UUO is a no-op
for everyone except the Font Compiler.

XGPUUO [OP=047, ADR=400075] CALLI 400075
--------------------------------------------------
MOVE AC,[CSB,,NSB]
XGPUUO AC,

CSB and NSB are the addresses of 20 word blocks. CSB is the Current
Status Block. The Font compiler reports it's state to the system by
the data it puts in the CSB before giving this UUO. NSB is the New
Status Block. The system issues commands to the Font Compiler by the
data it stores in the NSB when returning to the Font Compiler from
this UUO. This UUO will not return until the system has something
for the Font Compiler to do.

Word 0 of the status block is the opcode. All subsequent words are
operands.

OPCODE MEANING TO FC FROM SYSTEM MEANING TO SYSTEM FROM FC

0 Go away now. No-op (ready).
(System is finished with FC.)

1 Allocate. Allocation made.
(Word 1 has size (Word 1 has location
to allocate.) of allocation.)

2 Compile. Finished compiling.
(File name, ext, PPN (Word 1 has location
are in words 1, 2, 3; of base table.)
word 4 contains the
logical font number, 0:17.)
13.4 The XGP I/O Devices 178

3 Lock in core. Compiler error.
(System wants to (Word 1 contains
send data to XGP.) error code; see below.)

Error codes (in word 1 of block):

0 Illegal command. Word 2 has the rejected opcode.
1 Not enough core.
2 LOOKUP failure -- font file was not found.
Word 2 has the LOOKUP error code.
3 File error -- unexpected EOF.
4 File error -- redundant character.
5 Disk error.
6 Logical font number too big.
7 File error -- other illegal format.
13.5 Dectapes I/O Devices 179

13.5 Dectapes

A dectape consists of a sequence of 1102 200-word blocks (numbered
from 0 to 1101) which can be allocated to dectape files. There
several formats that have been used for allocating blocks to files.
The format in use at Stanford is called OLD DECTAPE FORMAT (or
sometimes PDP-6 FORMAT). Stanford's system is capable of
reading/writing only the old dectape file format. However, the user
can read and/or write almost any block on a tape (block 0 cannot be
written because of the hardware) and can thus simulate any format
desired (see the UDSD bit below).

Dectape I/O Status Word Summary

BITS OCTAL NAME MEANING OF A 1

21 0,,40000 IOBKTL Dectape block number out of
bounds.

29 0,,100 UDSD The system should treat the
tape as if it had no
directory. In this mode, the
user can read and/or write
blocks on the tape in any
format he desires. The USETI
and USETO UUOs (see Section
2.13) can be used to select
which block will be read next
and which block will be
written next. The UGETF UUO
(see page 35) will return a
word whose left half contains
the number of the next block
to be read and whose right
half contains the number of
the next block to be written.

Old Dectape Format

In the old format (still standard at Stanford) block 0 is not used,
block 1 is the directory which contains names of and pointers to all
the files on the tape, and blocks 2 through 1101 are available for
data.
13.5 Dectapes I/O Devices 180

Word 0 of the directory contains:

<LBU>,,5

where <LBU> is the number of the last block in use on the tape. When
you do a UGETF UUO (see page 35) this number gets incremented by one
and the result is returned as the number of the block you may use.
The "5" points to the word within the directory block where the file
entries begin.

Words 1:4 of the directory are not used at all. Words 5:174 are
grouped in 4-word entries, one for each file on the tape. Thus a
tape can hold a maximum of =30 files in the old format. The four
words for each file contain exactly the information you get back from
a LOOKUP, namely:

A zero entry marks the end of the directory.

For files written in buffered mode, each block contains (at most) 177
words of data, with the first word of each block containing

where <BN> is the number of the next block in the file, or zero if
none, and <WC> is the count of data words in this block.

Files written in dump mode have 200 words of data in each block and
have no block-to-block pointers or word counts. Such files are
always written on consecutive blocks of the tape. When a user writes
a dectape file in dump mode, no information is stored with the file
to indicate how long it is. Thus the user should include this
information either in the data itself or possibly in the fourth word
of the filename block when the ENTER is done.

UTPCLR [OP=047, ADR=13] CALLI 13
--------------------------------------------------
UTPCLR <channel number>,

The UTPCLR UUO causes the directory of the dectape initialized on the
channel indicated to be cleared. This means that the free block
pointer is set to point to block number 2 and all file entries in the
13.5 Dectapes I/O Devices 181

directory are zeroed. The tape can then be reused as if it were a
new tape. This UUO is a no-op for all devices but dectapes.
13.6 Magnetic Tapes I/O Devices 182

13.6 Magnetic Tapes

Data on magnetic tapes is written in files with each file being
terminated with an end-of-file mark. The logical end of tape is
indicated by two consecutive end-of-file marks with no intervening
data.

(The mag tape is not a directory device. No filenames are associated
with mag tape files, and the LOOKUP, ENTER and RENAME UUOs are no-ops
with mag tapes.)

Data on mag tapes can be written in any of the standard modes. One
of these is provided especially for mag tapes: mode 16--dump record
mode. This mode causes data to be transferred in 200-word records,
whereas normal dump mode (mode 17) transmits data in one large
record.

Magnetic Tape I/O Status Word Summary

BITS OCTAL NAME MEANING OF A 1

24 0,,4000 IOBOT The tape is at load point.

25 0,,2000 IOTEND The physical end of the tape
has been reached. If you
reach the end of the tape
while reading or writing, the
IOIMPM error bit will also be
turned on.

26 0,,1000 IOPAR The tape is being written or
read in even parity, which is
non-standard.

27:28 0,,600 These two bits indicate the
tape density: 0 and 2 mean 556
bits per inch, 1 means 200
bpi, and 3 means 800 bpi.
Although 800 bpi is the most
efficient, 556 bpi is more
reliable; 200 bpi is
relatively inefficient.

29 0,,100 IONRCK No re-reading is to be done.
Re-reading is usually done on
13.6 Magnetic Tapes I/O Devices 183

both output and input when an
error is detected. After =10
tries the system gives up and
sets an error bit.
13.6 Magnetic Tapes I/O Devices 184

MTAPE UUO for Magnetic Tapes

The following UUO is provided for doing all the special things
necessary with mag tapes.

MTAPE [OP=072]
--------------------------------------------------
MTAPE <channel number>,<function number>

If there is a mag tape open on the channel indicated by the AC field
of an MTAPE UUO, then the above form of MTAPE is assumed. The effect
of the MTAPE then depends on the function number appearing in the
address field. The function numbers and their meanings are given
below.

FUNCTION MEANING

0 Wait for any operation going on to complete.

1 Rewind the tape.

3 Write an end-of-file mark on the tape.

6 Advance the tape one record.

7 Backspace the tape one record.

10 Advance the tape to the logical end of tape.
Logical end of tape is signified by two
consecutive end-of-file marks. The tape is left
positioned after the second mark by this
operation.

11 Rewind the tape.

13 Write three inches of blank tape. The purpose of
this is to cause a bad spot on the tape to be
ignored. Perfectly blank tape looks like an
end-of-record mark to the controller and is
ignored. The monitor automatically writes blank
tape over bad spots on the tape.
13.6 Magnetic Tapes I/O Devices 185

16 Advance the tape one file. The tape is positioned
after the end-of-file mark that terminates the
file.

17 Backspace the tape one file. The tape is
positioned before the end-of-file mark at the end
of the previous file.
13.7 Paper Tape Punch/Plotter I/O Devices 186

13.7 Paper Tape Punch/Plotter

The paper tape punch and the plotter are considered the same device
by the system; this device has the sixbit name PTP. There is a
switch on the PDP-6 that determines whether data output to the PTP
actually goes to the punch or to the plotter. This switch is
normally kept in the plotter position.

There are several different modes in which the PTP can be operated.
Normally, only one of these (mode 10) is used with the plotter. Each
mode and its meaning with the PTP are described below.

MODES MEANING

0,1 Character modes. Seven bit characters are punched
with the eighth hole as an even parity bit. A
delete (ascii 177) is punched after every carriage
return, vertical tab and horizontal tab, and 30
frames of blank tape are fed after every form feed.

10,110 Image binary modes. The right-most eight bits
(bits 28:35--the 0,,377 bits) of each word are
punched directly as the eight bits on a frame of
paper tape. This is the mode used with the plotter
because the bits are sent exactly as they appear in
your buffer.

13 Binary mode. Every word in your buffer is punched
on 6 paper tape frames with 6 bits in each frame.
The seventh hole is never punched and the eighth
hole always is.

14 Checksum mode. This mode is the same as mode 13
except that before each buffer is punched, the
checksum of that buffer and its data word count are
punched. These two numbers appear in the left and
right halves respectively of the first word (6
frames) punched. After the data words have been
punched, 30 frames of blank tape are fed and then a
zero word is punched (a zero word is 6 frames each
with only the eighth hole punched).

100,101 No-conversion modes. These are buffered character
modes in which 7-bit characters are extracted from
your buffer and punched in the first seven holes of
each frame on the paper tape. The eighth hole is
always punched and nothing special is done for any
characters.
13.7 Paper Tape Punch/Plotter I/O Devices 187

113,114 No-eighth-hole modes. These modes are the same as
mode 13 except that the eighth hole is never
punched.
13.8 Paper Tape Reader I/O Devices 188

13.8 Paper Tape Reader

The paper tape reader (PTR) has four distinct modes, which are very
similar in operation to the first four modes of the paper tape punch.
Each mode and its meaning is explained below. See also Section 13.7
on the paper tape punch.

MODES MEANING

0,1 Character modes. From each frame on the paper tape
a 7-bit byte is taken, with the eighth hole
ignored. These 7-bit bytes are packed 5 to a word
in your input buffer. Nulls (ascii 0) and deletes
(ascii 177) on the tape are ignored.

10 Image mode. Each frame on the paper tape is
returned to you exactly as it appears on the tape,
with each 8-bit frame placed in the low order bits
(bits 28:35--the 0,,377 bits) of a single buffer
word.

13 Binary mode. Only those tape frames with the
eighth hole punched are looked at in this mode.
The seventh hole of each frame is ignored
completely and the first 6 holes of each frame with
the eighth hole punched are returned packed 6
frames to a buffer word.

14 Checksum mode. This mode is the same as mode 13
except that the tape is assumed to contain a
checksum and word count at the front of each buffer
of data. The checksum is checked on input to
insure accuracy of the transfers.
13.9 User Disk Pack I/O Devices 189

13.9 User Disk Pack

A user with a large quantity of data that he needs to have available
on high-speed storage can make use of a User Disk Pack (UDP). The
UDP (physical name UDP0) can only be read/written in dump mode. A
disk pack has =7600 tracks, numbered 0 to =7599; the last track
(number =7599) is used to hold a password. Each track consists of
=19 records, numbered 0 to =18; record 0 is 40 words long and each of
records 1 to =18 is 200 words long.

Unlike most other devices that can operate in dump mode, the UDP
accepts not a list of dump mode commands but only a single dump mode
command for each input or output operation. A UDP dump mode command
consists of two words, the first of which is the same as a normal
dump mode command and the second of which contains the UDP location
where the transfer is to start. Thus a UDP dump mode command looks
like this:

-<word count>,,<in-core location of data>-1
<record number>,,<track number>

where <track number> should be in the range from 0 through =7598 and
indicates on which track of the pack the transfer is to start and
<record number> should be in the range from 0 through =18 and
indicates at which record within the specified track the transfer is
to start. To effect a UDP data transfer, an INPUT or OUTPUT UUO is
given with the effective address pointing to the dump mode command.

WARNING: When an output indicates that only part of a record is to be
written, the remainder of the record is written with zeroes. Also,
as with the disk, if an ODD number of words are written out, the low
order 4 bits (bits 0,,17) of the last word are lost and are written
as zero.

Before any data can be written onto a UDP, the program desiring to do
the output must do an ENTER UUO to check the UDP password. The
RENAME UUO is used to change a UDP password. Data can be read from a
UDP without first giving the password.

If a disk error occurs during a RENAME or ENTER UUO, then unless bit
28 (the 0,,200 bit) is on in the I/O status word, an error message
(BAD RETRIEVAL) will be typed out and the program stopped. If bit 28
is on when bad retrieval is detected, the error return is taken and
an error code of 10 is returned in the right half of the word after
the password.
13.9 User Disk Pack I/O Devices 190

ENTER [OP=077]
--------------------------------------------------
ENTER <channel number>,ADR
<error return>

ADR: <password>
<returned error code>

An ENTER must be done to check the password before any data can be
written on a UDP. The word at location ADR is compared against the
password written on the UDP, if any. If there is no password on the
UDP, if the UDP password is zero, or if the word at ADR matches the
UDP password, then write permission is granted to the program and the
skip return is taken from the ENTER. Otherwise write permission is
rejected and the direct error return is taken with an error code of 2
(protection violation) returned in the right half of ADR+1.

RENAME [OP=055]
--------------------------------------------------
RENAME <channel number>,ADR
<error return>

ADR: <new password>
<returned error code>

The RENAME UUO is used to change the password for a UDP. An ENTER
must have been done to acquire write permission for the UDP. The
password specified in location ADR replaces the old UDP password. A
zero password means an ENTER (see above) will always succeed. If the
change of password is successful, the skip return is taken. If no
ENTER has been done, then an error message will be printed out and
the program stopped.

UDP I/O Status Word Summary

BITS OCTAL NAME MEANING OF A 1

28 0,,200 GARBIT Suppress error message on bad
retrieval from ENTER or
RENAME; instead take error
return with code 10.
13.9 User Disk Pack I/O Devices 191

The following I/O UUOs are illegal with the UDP: LOOKUP, USETO,
USETI, UGETF and MTAPE.
13.10 AD/DA Converter I/O Devices 192

13.10 AD/DA Converter

The Analog-to-Digital/Digital-to-Analog Converter, hereinafter
referred to as the AD (its physical name), operates only in dump
mode. The only legal modes for the AD are 16 and 17. Mode 17 is the
normal mode. In mode 16 each time a transfer is requested, it will
not be started until bit 28 (0,,200 bit) of the spacewar buttons is
on (see the SPWBUT UUO on page 149).

Note that output from the AD operates only the 4-channel sound
system. Input can come from various sources; see the explanation of
the input channel number below. Data from or to the AD is in 12-bit
bytes packed three to a word.

Normally, an INPUT or OUTPUT will not return until the transfer is
finished; however, if bit 29 (0,,100 bit) is on in the AD status
word, the UUO will return immediately so that you may overlap
computation with the transfer, for instance if you are trying to keep
transfers going continuously. To wait for the last transfer to
finish, use the WAIT UUO (see page 32).

The AD does not take standard dump mode command lists. Each INPUT or
OUTPUT UUO should point to a 5-word block which should contain the
following information:

-<word count>,,<address of data block>-1
<136 CONO bits>
<AD CONO bits>
<CONI bits from 136 returned here after transfer>
<CONI bits from AD returned here after transfer>

The 136 is an interface for the AD. The CONO bits to the 136
interface should be 4250 for input and 3650 for output (unless you
know about the 136 in detail).

Here is an explanation of the AD CONO bits.

BITS OCTAL MEANINGS OF AD CONO BITS

18:23 0,,770000 This is the AD multiplex input channel
number. If auto-indexing is used, this
is the beginning channel number. You
can find a list of the channel numbers
and what devices they correspond to by
looking at SAILON 21, Addendum 1.1,
entitled A/D CONVERTER MULTIPLEXER PATCH
PANEL AND CHANNEL ASSIGNMENTS, by Edward
Panofsky. The channel number is not
pertinent for output.
13.10 AD/DA Converter I/O Devices 193

24 0,,4000 Reset bit. This bit should be 1 for
output, 0 for input.

25 0,,2000 Input: auto-indexing. If this bit is a
one, then when a sample has been
transmitted, the multiplex channel
number (see bits 18:23 above) will be
incremented by one before the next
sample is transmitted.

26 0,,1000 Input: complement low-order bit of
channel number after each sample. With
this bit on, if you start out with
either channel 16 or 17, for example,
then samples will alternate between
these two channels. With input, if both
this bit and bit 25 are set, a logical
conflict exists and nothing will happen.

25:26 0,,3000 Output: number of channels of sound. In
this field, a 0 means 1 channel, 1 means
2 channels, 2 means nothing, and 3 means
4 channels. Samples are sent
alternately to the number of channels
indicated.

30:32 0,,70 Clock speed. The meanings of the
different values possible for this field
are: 0--free run, 1--20KHz, 2--25KHz,
3--10KHz, 4--50KHz, and 5--100KHz. FREE
RUN means that as soon as one conversion
is done another one is begun; the actual
speed under this condition can be
somewhat irregular and is probably
somewhere between 100KHz and 200KHz.
The 100KHz speed (5) is not very
reliable.

The system does no error checking for you so you must do your own
with the bits returned in words 3 and 4 of the block. Of these bits,
the only one that is really important is the 136 data-missed bit, bit
23 (0,,10000 bit) in word 3. If this bit is on, then a sample was
lost in the transfer and you should do the transfer again.

If you are running in continuous mode, (bit 29 set in status word),
then the CONI words for the 136 and the AD will not be returned
unless the device catches up with you. This is one way of testing
for errors in continuous mode transfers; if you get the CONI words
back, then either there was some data error (causing the device to
13.10 AD/DA Converter I/O Devices 194

finish early) or you did not supply/accept data as fast as the device
could go.

Here is a sample input block to transfer 100 words to an address
called ADR from channel 10 with a clock rate of 20KHz.

IOWD 100,ADR
4250
100010
0
0

Here is a similar output block.

IOWD 100,ADR
3650
104010
0
0

AD I/O Status Word Summary

BITS OCTAL MEANING OF A 1

29 0,,100 Continuous mode. An INPUT or OUTPUT UUO
will return without waiting for its
transfer to complete. However, it will
wait for any previous transfer still in
progress (whether input or output) to
finish before the UUO returns. Thus you
cannot be doing both input and output
simultaneously.
13.11 TV Cameras I/O Devices 195

13.11 TV Cameras

For reading the TV cameras, it is recommended that you use already
existing routines rather than write your own. However, for those who
are stubborn enough to want to do it themselves, here is an
explanation of how to read the cameras.

To read a television camera, you first INIT or OPEN device TV in mode
17 and then do dump mode inputs. The TV does not take standard dump
mode command lists. The effective address of an INPUT UUO for the TV
should point to a 4-word block that contains the following
information:

-<word count>,,<address of first word>
<TV camera CONO bits>
<TV camera DATAO word>
<CONI bits from 167 returned here upon completion>

Thus the first word of this block contains the negative of the number
of words of data to be input and the address of the first word of the
block where this data is to go. (Note that this is not standard IOWD
format!) The second word contains (in the right half) the CONO bits
for the TV. These bits have the following meanings:

BITS OCTAL NAME MEANINGS OF TV CAMERA CONO
BITS

18:20 0,,700000 BCLIP The bottom converter clip
level. Each sample is a 4-bit
number representing the
intensity at a given point.
The =16 levels are taken from
the voltage range specified by
BCLIP and TCLIP (see below);
thus you can control the
camera's exposure setting from
your program. A voltage of
1.0 is put out at a very
bright spot and a voltage of 0
is put out at a completely
dark spot. BCLIP indicates
the voltage which is to
represent a sample of zero.
Only voltages above this value
will produce non-zero samples.
See the table below for the
voltage levels indicated by
the various possible values
for BCLIP.
13.11 TV Cameras I/O Devices 196

21:23 0,,700000 TCLIP The top clip level. This
value determines the voltage
which is to represent the
maximum sample value of 17.
All higher voltages will also
produce a sample of 17. See
BCLIP above and the table
below showing voltage levels
corresponding to the possible
values of TCLIP and BCLIP.

VALUE BCLIP TCLIP

0 .875 1.000
1 .750 .875
2 .625 .750
3 .500 .625
4 .375 .500
5 .250 .375
6 .125 .250
7 .000 .125

24:26 0,,7000 CAMERA The camera number. There are
eight possible camera numbers,
but not all of them are wired
in permanently. The cart
camera is number 0, the Cohu
camera is number 1, the Sierra
camera is number 2 and the
Kintel camera is number 3.

27:29 0,,700 VRESOL The vertical resolution
divided by two, minus one. A
zero here gets you every other
line, a one every fourth line,
etc.

30:34 0,,76 This field must contain a 1.

35 0,,1 Horizontal 1/2-sample offset.
If this bit is a one, the
samples within each line will
be taken from positions
approximately 1/2 sample width
to the right of the usual
positions. By doing two
transfers, one with this bit
off and one with it on, you
can essentially double the
horizontal resolution.
13.11 TV Cameras I/O Devices 197

Now here are the meanings for the bits in the DATAO word (third word
of block pointed to by the INPUT UUO).

BITS OCTAL NAME MEANING OF TV CAMERA DATAO
WORD

0:8 777,,0 YDISP The Y-coordinate displacement.
Here 0 is the top of the
screen; the bottom is about
400. This is the Y-coordinate
of the top line that you will
receive. Since you can
receive at most every other
line (see VRESOL above), to
get an entire picture you can
read the picture twice, first
with YDISP set to 0 for the
even numbered lines and then
with YDISP set to 1 for the
odd numbered lines.

9:17 777,,0 XDISP The X-coordinate displacement.
Here 0 is the left side of the
picture; the right side is
approximately 515.

18:26 0,,777000 WWIDTH The width of the picture in
words. Each word returned
will contain 9 4-bit samples.
WWIDTH specifies the number of
words returned for each line.
Thus you will get 9*WWIDTH
samples per line. The range
for this field is from 0 to
44.

The data you get from an INPUT is packed 9 4-bit samples to a word.
The first sample is from the upper left hand corner of the picture
specified by the X and Y displacements, horizontal width and word
count. Successive samples are from points just to the right of
previous points until the end of a line, after which the next sample
is from the leftmost point on the next line (the exact line depending
on the vertical resolution).

When the transfer is finished, the CONI bits from the IOP (the 167
data channel) are returned in the fourth word of the block pointed to
by the INPUT UUO. Also, if an error occurred during the transfer and
bit 29 (0,,100 bit) was on in the TV's device status word, then the
address within your core image where the transfer was terminated is
13.11 TV Cameras I/O Devices 198

returned to you in the left half of the CONI word (fourth word of
block). The important bits in this fourth word are explained below:

BITS OCTAL MEANINGS OF 1'S IN 167 CONI WORD

30 0,,40 DATA MISSED. A word (9 samples) was
missed by the memory and the transfer
was terminated. You cannot be sure that
you have a complete picture; thus you
should do the transfer again.

31 0,,20 NON-EX MEM. The camera referenced a
non-existent memory location. This
should never happen!

32 0,,10 JOB DONE. If the transfer has been
completed successfully, then this bit
will be on. If this bit is not on, then
the camera is hung and not responding;
for instance, the camera's power might
be off or your specifications might have
been illegal somehow.

TV I/O Status Word Summary

BITS OCTAL MEANING OF A 1

29 0,,100 Return data address at time of error in
left half of CONI word.
13.12 The IMP I/O Devices 199

13.12 The IMP

The IMP is the interface between the system and the ARPA network. To
do anything over the network, it is necessary to use the IMP. Before
explaining usage of the IMP, I will define some network terms.
However, these definitions do not describe all of the network
protocol. Anyone writing a program that utilizes the network should
first read the network documents in order to gain some understanding
of the protocol involved.

SOCKET: Any connection between two hosts involves two sockets, a send
socket on one end and a receive socket on the other end. In a normal
interaction, there will be two connections so that data can flow both
ways; thus four socket numbers are involved: a local send socket
number, a local receive socket number, a foreign send socket number,
and a foreign receive socket numbers. These numbers are internal
connection indices and are used to keep different interactions
separate. Of these four socket numbers, each receive socket number
must be even and each send socket number must be the odd number which
is one greater than the receive socket number at the same end. A
socket number is 32 bits long.

RFC--Request For Connection: To establish a connection, the
originating host sends an RFC to the destination host with a local
socket number and a foreign socket number as arguments. The
destination host can complete the connection by returning an RFC with
the same socket numbers, or can refuse the connection by returning a
close code. Normally two connections are made for full duplex.

LINK: Once a connection is established, an 8-bit link number is
assigned such that the 8-bit host number concatenated with the 8-bit
link number is unique at both ends of the connection. During the
lifetime of the connection, the link number is used to identity the
connection to the IMP network. The IMP itself is programmed in such
a way that only one message may be in transit on a particular link at
a time. The IMP signals the sending host that the message has
arrived by returning a RFNM (request for new message) with that link
number as an argument. All of this is invisible to the user.

ALLOCATION: The host to host protocol defines a kind of flow control
on a higher level than the RFNM control. This is the allocation
system. When a connection is first established, the receiving host
sends a control message telling the sending host how many bits and
messages can conveniently be buffered. The sending host must then
not send more than that many bits or messages without waiting for
more allocation from the receiving host. Although much of this is
unseen to the user, the user has control over how much allocation the
system will give the remote host. For data and file transfer
13.12 The IMP I/O Devices 200

purposes, it is convenient to increase the allocation over the system
default amount.

BYTE SIZE: Associated with each connection is a byte size that
specifies the type of data to move on that connection. The send side
indicates in its RFC what the byte size of the connection is to be;
the receive side of the connection has no choice in the matter.
Stanford allows byte sizes of 1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 32,
and 36 bits. Most other hosts allow only 8, 32, and 36 bits. The
standard TELNET connection is 8 bits with the rightmost 7 bits of
each byte being an ascii character unless the high-order bit (200
bit) is on, in which case the character is a command to the receiving
TELNET. A byte size is established for the life of a connection and
may not be changed until the connection is broken. When you do IMP
input (output), the data received (sent) is packed (unpacked) into
(from) your buffers effectively with IDPB (ILDB) instructions using
the connection byte size. Thus in buffered mode, after you have
INITed the IMP, you should change your buffer header's byte pointer
byte size to the connection byte size. In dump mode, you should
unpack (pack) the data with ILDBs (IDPBs) using the connection byte
size.

IMP I/O

The IMP is similar to any other sharable I/O device in that it may be
initialized with an INIT and released with a RELEAS, but it is
different in that one must first open a connection before one may
exchange data. Connections are opened and closed separately for the
receive side and the send side, even though the I/O channel number is
the same. One may open and close connections liberally without
having to do more than one INIT. The INPUT and OUTPUT UUOs are used
to read data from, and to send data over, the connection. The CLOSE
UUO may be used to close one or both of the send and receive
connections (the close-inhibit bits determine which sides are
closed). To open a connection or to get one of several special
functions, the user does an MTAPE UUO with the effective address
pointing to a variable length table whose first word is a code
number. This number determines the function of the UUO. These
functions will be explained below, but first here are explanations of
some bits relevant to the IMP.

The status of a connection is contained in several places. The
actual connection status is in a status word, one for each
connection. If you have both a receive and a send connection, then
you will have two status words. MTAPE 2 gives you these status
words. The bits are decoded as follows:
13.12 The IMP I/O Devices 201

BITS OCTAL NAME MEANING OF A 1

1 200000,,0 RFCS RFC sent.
2 100000,,0 RFCR RFC received.
3 40000,,0 CLSS Close sent.
4 20000,,0 CLSR Close received.
11 100,,0 INTINR Interrupt by receiver.
12 40,,0 INTINS Interrupt by sender.

The normal state of an open connection is 300000 in the left half,
possibly with other bits on that are not mentioned above (some bits
are used internally by the system). When a connection is closed or
closing, CLSS or CLSR will be on. No more data may be transmitted or
received over the connection at this point. The foreign host may
send us interrupts. He can send an interrupt from receiver or an
interrupt from sender. These can be received as user interrupts or
can be tested for explicitly by MTAPE 14. Interrupts can be sent
using MTAPE 11; interrupts generated by this UUO will not appear in
the connection status words for the user generating them.

More status bits occur in the I/O status word, which can be gotten
with a GETSTS UUO, or examined with a STATZ or STATO UUO, or cleared
with a SETSTS UUO. These bits are as follows:

BITS OCTAL NAME MEANINGS OF 1'S IN IMP I/O
STATUS WORD

25 0,,2000 HDEAD Host or destination IMP dead.
This means that the last
message sent stayed in the IMP
network for a certain length
of time without being eaten by
the destination. In this
case, the IMP flushes the
message and sends us back a
HOST DEAD message.

26 0,,1000 CTROV Foreign host goofed and sent
us more bits than we allocated
him. The system closes the
connection when this happens.

27 0,,400 RSET Foreign host sent us a reset,
which asks us to clear all our
tables of references to this
host. The connection is
closed. Some sites (including
CMU and Harvard) will, as
13.12 The IMP I/O Devices 202

standard procedure, send a
reset the first time we
connect to them after their
system has come up. In this
case, trying again will
succeed. In the more normal
case, RSET means the host has
just crashed and been brought
up again.

28 0,,200 TMO Timeout occurred. Your job
was in a wait state and timed
out (see MTAPE 17).

User interrupts can be taken on a number of conditions. These are
described below. See Section 9 to find out how to enable and receive
interrupts.

BITS OCTAL NAME INTERRUPT CONDITION

11 100,,0 INTINR Interrupt from foreign receive
side.

12 40,,0 INTINS Interrupt from foreign send
side.

13 20,,0 INTIMS Status change. One or more of
the bits CLSS, CLSR, RFCS,
RFCR has changed.

14 10,,0 INTINP Some new input has arrived.
The next INPUT UUO will not
wait. The INTINP interrupt is
generated every time a regular
data message is received by
the system. One can test for
data received and waiting in
the system with an MTAPE 10
UUO.

IMP MTAPEs

Now on to the MTAPEs themselves.
13.12 The IMP I/O Devices 203

MTAPE [OP=072]
--------------------------------------------------
MTAPE <channel number>,ADR

ADR: <function number>
<other data depending on function number>
...

This is the general form of the IMP MTAPE UUOs. The function number
specified at ADR determines the meaning of the UUO. What is expected
and/or returned in the words following ADR is also dependent on the
function number. The various functions are explained below.

Some of these functions may go into a wait state. They will be
awakened either because of their normal wakeup condition, or some
special condition. Some of the special conditions that may occur are
specified by the bits in the right half of the I/O status word. For
instance, if you are waiting for input and a reset arrives, the job
is awakened and RSET is set. An I/O error bit (one of IOBKTL,
IODTER, IODERR, IOIMPM or IODEND) will be set if the wakeup was due
to a special condition, so the normal IN and OUT UUOs will skip if
the wakeup was not due to the normal wakeup condition.

In any operation which expects the status word to be returned in word
1 (CONNECT, LISTEN, etc), an error code may be returned instead in
the rightmost 6-bits. These errors are as follows:

CODE NAME MEANING

1 SIU Socket in use. There is already a connection
on the specified local socket number.

2 CCS Can't change socket numbers. This means a
foreign socket number has already been set
and an RFC received for this local socket
number. You can't change the socket number
because the foreign host already knows what
it is.

3 SYS Horrible system error. Can't happen.

4 NLA No link available. System IMP capacity
exceeded.

5 ILB Illegal byte size.

6 IDD IMP dead.
13.12 The IMP I/O Devices 204

Here are the various IMP MTAPE functions available.

--------------------------------------------------
ADR: 0 ;CONNECT
ADR+1: <status bits returned here>
ADR+2: <local socket number, 32 bits, right-justified>
ADR+3: <wait flag: non-zero for wait for connection>
ADR+4: <byte size if sending, else byte size returned here>
ADR+5: <foreign socket number>
ADR+6: <host number, 8 bits, right-justified>

An RFC is sent to the host whose number is in word 6 with the local
socket number taken from word 2 and the foreign socket number taken
from word 5. If word 3 is non-zero, the user program goes into RFC
wait until timed out (see MTAPE 17) or until an RFC with matching
socket numbers and host number arrives. If a matching RFC has
already arrived from the foreign host, this UUO will not wait, but
will complete the connection immediately. If you wish to open a
receive connection, the local socket number must be even and the
foreign socket number odd. To open a send connection, the local
socket number must be odd and the foreign socket number even.

If you are opening a receive connection (local socket number is
even), and either the wait flag (word 3) is on or a matching RFC was
already waiting, then the connection byte size is returned in word 4.
If you are opening a send connection (local socket number odd), you
must specify the connection byte size in word 4.

--------------------------------------------------
ADR: 1 ;LISTEN
ADR+1: <status bits returned here>
ADR+2: <local socket number>
ADR+3: <wait flag: non-zero for wait>
ADR+4: <byte size if sending, else byte size returned here>
ADR+5: <foreign socket number returned here>
ADR+6: <host number returned here>

This function is used to listen for an RFC from a foreign host to a
specific socket number here and to connect to that foreign host
automatically when the RFC is received. If word 3 is non-zero, this
UUO will wait for the connection to be made.

When an RFC for the specified socket arrives from a foreign host, a
13.12 The IMP I/O Devices 205

connection is made. If the local socket number is even (receive
side), and either the wait flag (word 3) is on or the RFC was already
waiting for you, then the connection byte size is returned in word 4.
If the local socket number is odd (send side), you must specify the
byte size in word 4. The foreign socket number to which you get
connected is returned in word 5; a -1 is returned if no connection
has been made (wait flag off). The foreign host number is returned
in word 6.

--------------------------------------------------
ADR: 2 ;GET STATUS
ADR+1: <status bits for local send side returned here>
ADR+2: <status bits for local receive side returned here>

This function returns the status bits for both the send side and the
receive side of a connection. These bits are explained on page 201.
If the connection is not open, zero is stored. If a reset has been
received, both CLSS and CLSR will be on.

--------------------------------------------------
ADR: 3 ;TERMINATE CONNECTION
ADR+1: <status bits returned here>
ADR+2: <local socket number>
ADR+3: <Wait flag: non-zero to wait for close>

This sends a close to the foreign host for the socket specified in
word 2. If word 3 is non-zero, the job is placed in CLS wait until a
return close is received, or the CLS timeout occurs (signified by TMO
being on in the I/O status word).

--------------------------------------------------
ADR: 4 ;WAIT FOR CONNECTION COMPLETION
ADR+1: <status bits returned here>
ADR+2: <socket number>

This is meaningful only if a CONNECT or LISTEN was given without
waiting (word 3 = 0). In this case, the job is put into RFC wait
until an RFC arrives or a timeout occurs.
13.12 The IMP I/O Devices 206

--------------------------------------------------
ADR: 5 ;DUMP MONITOR TABLES
ADR+1: <number of words of tables desired>
ADR+2: <address of place to put tables>

This dumps the monitor tables into your core image. The format of
these tables is much too lengthy to be discussed here, but is sort of
described in IMPDDB[S,SYS] pages 6 and 7. The part that is dumped is
after the label SYSTBS.

--------------------------------------------------
ADR: 6 ;WAKEUP MAIN PROCESS

This function is valid only when given at interrupt level. This will
wake up the main process if it is in any wait state due to the IMP.
It also sets TMO in the I/O status bits.

--------------------------------------------------
ADR: 7 ;GET SOCKET NUMBERS AND HOST-LINK NUMBERS
ADR+1: <host-link number for send side>
ADR+2: <local send socket>
ADR+3: <foreign receive socket>
ADR+4: <host-link number for receive side>
ADR+5: <local receive socket>
ADR+6: <foreign send socket>

This function returns the above socket numbers and host-link numbers.
A host-link number is a 16 bit right-justified quantity. The first 8
bits are the host number and the last 8 bits are the link number.

--------------------------------------------------
ADR: 10 ;SKIP IF ANY INPUT PRESENT

This function skips if there is input waiting that has not yet been
transferred to the user's buffers. Otherwise the direct return is
taken.
13.12 The IMP I/O Devices 207

--------------------------------------------------
ADR: 11 ;SEND INTERRUPT
ADR+1: <status bits returned here>
ADR+2: <local socket number>

This function sends an interrupt by receiver (INR) if the socket
number is even (receive side) and an interrupt by sender (INS) if the
socket number is odd (send side).

--------------------------------------------------
ADR: 12 ;RESURRECT IMP IF DOWN

This is a privileged UUO and is applicable only if the IMP system is
down, in which case it attempts to bring it up.

--------------------------------------------------
ADR: 13 ;BLESS HOST
ADR+1: <host number>

If a destination IMP returns a host dead message, a bit is set in the
system and no further transfers are permitted to that host. This UUO
clears that bit and sends a null message to the host to see if he is
still dead.

--------------------------------------------------
ADR: 14 ;TEST AND CLEAR INTERRUPTS
ADR+1: <-1 returned here if any send side interrupts>
ADR+2: <-1 returned here if any receive side interrupts>

This UUO tells you if you have received either an interrupt by
foreign sender or an interrupt by foreign receiver. It also clears
the interrupt condition. For each of the two types of interrupts, a
minus one is returned if the corresponding interrupt has been
received, and a zero is returned if no interrupt has been received.
When one of these interrupts arrives, the corresponding bit (INTINS
or INTINR) is set in the status word for that connection, and if you
are enabled for that interrupt condition, a user interrupt is
generated.
13.12 The IMP I/O Devices 208

--------------------------------------------------
ADR: 15 ;ALLOCATE
ADR+1: <type code: 0 for as specified, 1 for system max,
2 for min, and 3 for system default values>
ADR+2: <number of bits of allocation (for type = 0)>
ADR+3: <number of messages of allocation (for type = 0)>

This changes the allocation we have given the foreign host. If this
UUO is not given, the system default value is used, which is fairly
small. The system maximum is =1024 words, and the system minimum is
2 words. The default value is about =50 words. We allocate in two
dimensions. We allocate both the number of bits and the number of
messages he may send. Since free storage blocks are about =50 words
long, the system maximum number of messages is 1024/50. If the
function code (word 1) is 0, the new allocation is taken from words 2
and 3, clipped to fit within the system maximum and minimum, and set
accordingly. Notice that if the connection is not yet open, this
does not actually cause the allocation to happen, just sets the
values that will be given. Allocation does not actually occur until
the first IN (INPUT) UUO is given, or an MTAPE 10 is given. Do not
expect any input interrupts until one of these UUOs has been given!
If we do not allocate him anything, nothing will happen!

--------------------------------------------------
ADR: 16 ;GET ALLOCATIONS
ADR+1: <number of bits we have allocated him>
ADR+2: <number of messages we have allocated him>
ADR+3: <number of bits he has left>
ADR+4: <number of messages he has left>
ADR+5: <number of bits in free storage>
ADR+6: <number of messages in free storage>
ADR+7: <number of bits he has allocated us>
ADR+10: <number of messages he has allocated us>

Function 16 returns the above allocation values.
13.12 The IMP I/O Devices 209

--------------------------------------------------
ADR: 17 ;SET TIMEOUTS
ADR+1: <word of 6-bit bytes: number of 2-second units
for timeouts on CLS, RFNM, ALLOC, RFC, INP;
0 means never timeout.>

A job can enter a wait state waiting for any one of five different
kinds of messages to arrive over the network: CLS (a return close of
a connection), RFNM (a request for new message, indicating that the
last message sent reached its destination), ALLOC (an allocation from
a foreign receive socket, needed so that we can send some data), RFC
(a request for connection, necessary to complete a connection), or
INP (input data from a foreign host). In each of these cases, a
timeout may be set. IMP MTAPE function 17 takes 6-bit fields from
word 1 for five timeout values: CLS timeout is in bits 0:5 (770000,,0
bits), RFNM in bits 6:11 (7700,,0 bits), ALLOC in bits 12:17 (77,,0
bits), RFC in bits 18:23 (0,,770000 bits), and INP in bits 24:29
(0,,7700 bits). The value in each field is the number of 2-second
units of timeout duration. The maximum timeout duration is thus =126
(2*63) seconds. Zero in any field means never time out waiting for
that condition (i.e., wait forever for that condition). Bits 30:35
(0,,77 bits) are not currently used.

When a RFNM, ALLOC or INP timeout occurs, one or more I/O status
error bits are set (which will cause an IN or OUT UUO to take the
error return). When an RFC or CLS timeout occurs, the UUO in
progress just goes on as if it had never tried to wait. When any of
the five timeouts occurs, the timeout bit (TMO) is set in the
connection status word.

Note that we can go into CLS wait inside a CONNECT or LISTEN if the
local socket has a half-closed connection associated with it. For
this reason, it is always good to wait at least a few seconds for the
return CLS.

The system default timeout values are 6 seconds for CLS, 40 seconds
for RFNM, and no timeout for ALLOC, RFC, and INP.

--------------------------------------------------
ADR: 20 ;GET TIMEOUTS
ADR+1: <current timeout word returned here>

Function 20 returns the current timeout word as defined above in
function 17.
14. Examples Examples 210

SECTION 14

EXAMPLES

This section presents some examples of usage of UUOs. There are
example programs that do file I/O, run display programs and use
interrupts. All of the examples are written in FAIL; note the
comments appearing alongside the code.

14.1 Example of General I/O

Here is a program that copies a text file called FOO into a new file
called GARPLY.TMP (copying is done character by character).

TITLE EXAMPLE OF GENERAL I/O

CHR←1 ;AC to hold character being copied into new file
P←17 ;AC for pushdown pointer

IC←←0 ;channel number used for input
OC←←1 ;channel number used for output

IOTEST: RESET ;Good thing to start with.
MOVE P,[IOWD LPDL,PDL] ;Set up pushdown pointer.

INIT IC,0 ;Initialize device DSK on channel IC
SIXBIT /DSK/ ; in mode 0 with input buffer
IBUF ; header at IBUF.
HALT . ;Impossible error: can't INIT the DSK.

SETZM INAME+3 ;Clear the PPN word of LOOKUP block--use
; current DISK PPN (ALIAS) for old file.
; This word is clobbered by LOOKUPs.
LOOKUP IC,INAME ;Open file FOO for reading.
JRST NOLOOK ;LOOKUP failed--find out why.

INIT OC,0 ;Initialize device DSK on channel OC
SIXBIT /DSK/ ; in mode 0 with output buffer
OBUF,,0 ; header at OBUF.
HALT . ;HALT on failure.
14.1 Example of General I/O Examples 211

SETZM ONAME+3 ;Clear the PPN word of ENTER block--use
; current DISK PPN (ALIAS) for new file.
SETZM ONAME+2 ;Set protection to 000, use current
; date/time for date/time file written.
ENTER OC,ONAME ;Open file GARPLY.TMP for output.
JRST NOENTR ;ENTER failed--find out why.

LOOP: PUSHJ P,GETCH ;Get a character from input file.
JRST DONE ;End-of-file return from GETCH.
PUSHJ P,PUTCH ;Put character into output file.
JRST LOOP ;Loop until EOF.

DONE: RELEAS OC, ;Close output file and release DSK.
RELEAS IC, ;Close input file and release DSK.
EXIT ;Return to monitor level.

NOLOOK: OUTSTR [ASCIZ /
LOOKUP FAILED -- /]
HRRZ CHR,INAME+1 ;Get LOOKUP error code.
CAILE CHR,ERRMAX ;Make sure error code is reasonable.
MOVEI CHR,ERRMAX ;Unreasonable code.
OUTSTR @ERROR(CHR) ;Type appropriate error message.
HALT .

NOENTR: OUTSTR [ASCIZ /
ENTER FAILED -- /]
HRRZ CHR,ONAME+1 ;Get ENTER error code.
CAILE CHR,ERRMAX ;Make sure error code is reasonable.
MOVEI CHR,ERRMAX ;Unreasonable code.
OUTSTR @ERROR(CHR) ;Type appropriate error message.
HALT .

GETCH: SOSG IBUF+2 ;Decrement character count for input buffer.
IN IC, ;No more in current buffer. Read some more.
JRST GETCH1 ;Go get a character out of input buffer.

STATZ IC,20000 ;IN failed. Have we hit end of file?
POPJ P, ;Yes. Take direct return.
OUTSTR [ASCIZ /
INPUT FILE ERROR.
/] ;No. Type error message.
HALT . ;HALT on some input error.

GETCH1: ILDB CHR,IBUF+1 ;Get a character out of input buffer.
AOS (P) ;Take skip return from GETCH with
POPJ P, ; new character.
14.1 Example of General I/O Examples 212

PUTCH: SOSG OBUF+2 ;Decrement character count for output buffer.
OUT OC, ;No room. Do output and get fresh buffer.
JRST PUTCH1 ;Go put character into output buffer.
OUTSTR [ASCIZ /
OUTPUT FILE ERROR.
/] ;OUT UUO failed--type error message.
HALT . ;HALT on any output error.

PUTCH1: IDPB CHR,OBUF+1 ;Put character into output buffer.
POPJ P, ;Return from PUTCH.

OBUF: BLOCK 3 ;Output buffer header
IBUF: BLOCK 3 ;Input buffer header
INAME: SIXBIT /FOO/ ;Block used for LOOKUP: file name of FOO.
BLOCK 3 ; No extension, space for date and PPN words.
ONAME: SIXBIT /GARPLY/;Block used for ENTER: file name of GARPLY,
SIXBIT /TMP/ ; extension of TMP.
BLOCK 2 ; Space for date word and PPN word.

LPDL←←10 ;Length of pushdown list
PDL: BLOCK LPDL ;Block for pushdown list

ERROR: [ASCIZ /NO SUCH FILE.
/]
[ASCIZ /ILLEGAL PPN.
/]
[ASCIZ /PROTECTION FAILURE.
/]
[ASCIZ /FILE BUSY.
/]
ERRMAX←←.-ERROR
[ASCIZ /HOORRIIBBLEL ERRO RNBR 87.
/] ;impossible error

END IOTEST ;End of program, starting address.

14.2 Example of Display Programming

Here is a simple program to display some (fixed) text on either a III
or a Data Disc. This program also positions the page printer at the
bottom of the screen and draws a vector across the screen just above
the page printer.
14.2 Example of Display Programming Examples 213

TITLE DISPLAY PROGRAMMING EXAMPLE

A←1
L←2 ;AC used to hold TTY line characteristics

DDDLIN←←20000 ;Data Disc bit in line characteristics.
IIILIN←←400000 ;III bit in line characteristics.

; Data-Disc macros and definitions
; Command word -- alternating commands and parameters:
DEFINE CW(C1,B1,C2,B2,C3,B3) <
<BYTE (8)<B1>,<B2>,<B3> (3)<C1>,<C2>,<C3>>!4
>

; Command names for DD command bytes
EXCT←←0 ;Execute
FNCN←←1 ALPHBG←←6 ALPHA←←46 ;Function, usual value bytes
CHNL←←2 ;Channel select
COLM←←3 ;Column select
HILIN←←4 ;Set high 5 bits of line address
LOLIN←←5 ;Set low 4 bits of line address

DISPLA: RESET ;A good practice is to start with a RESET.
SETO L, ;Get TTY's line characteristics to find out
GETLIN L ; if TTY is a III or a Data Disc.
AOJE L,FINISH ;Jump if job is detached (no TTY).
TLNN L,DDDLIN!IIILIN
JRST NOTDPY ;Jump if TTY is not a display.

PPSEL 1 ;Select new piece of paper, and
DPYPOS -500 ; position near bottom of screen with
DPYSIZ 3002 ; 3 glitches and 2 lines per glitch.

JUMPL L,DOIII ;Jump if III (sign bit is IIILIN)
DDUPG [[CW FNCN,17,CHNL,0,FNCN,ALPHA↔0]↔2]
;Erase DD screen first.
MOVE A,[CW FNCN,ALPHA,CHNL,0,FNCN,ALPHA]
;DD command word to do channel select
; and set up function register for text.
MOVEM A,DPPROG ;Put into display program.

SKIPA A,[CW COLM,2,HILIN,2,LOLIN,4]
;DD command word to do column/line selects.
DOIII: MOVE A,[BYTE (11)<-777>,640 (3)2,3 (2)1,2 (4)6]
;III long vector word to draw an invisible
; absolute vector to the upper left corner
; of the screen, and select brightness
; of 2, size of 3.
MOVEM A,DPPROG+1 ;Store in display program.
14.2 Example of Display Programming Examples 214

UPGIOT 1,DPHEAD ;Run display program (on piece of
; glass number 1 if III).

JUMPL L,DOIII2 ;Jump if III.
UPGIOT DDDHDR ;Draw line across DD screen.
JRST FINISH

DOIII2: UPGIOT 2,IIIHDR ;Draw vector on III, using POG # 2.

FINISH: EXIT 1, ;Done. Don't do normal EXIT which
; would RESET the display.
EXIT ;In case user types CONTINUE.

NOTDPY: OUTSTR [ASCIZ /
This program only works on displays./]
EXIT

DPHEAD: 200000,,DPPROG ;Double-field mode bit,,address of disp prog
DPLEN ;Length of display program
0
DPPROG+1 ;Address of low order line select in DD prog

DPPROG: BLOCK 2 ;Space for command and position words.
ASCID /This is the text to be displayed on the first line.
And this is the text for the second line.

Note: The ASCID statement turns on the low order bit in each word
generated, thus causing such words to be taken as text words when
they appear in a display program for either III or DD.

Note: For DD, the last line of text must have a CRLF at its end, or
the display program must end with an execute; otherwise the last line
of text will not be displayed.

This is the last text line that will be displayed.
/
0 ;For DD, a HALT (zero) must end the program, or the
; system will zero the last word of the program.
; Zero also stops (but is unnecessary in) a III prog.

DPLEN←←.-DPPROG ;Length of display program.
14.2 Example of Display Programming Examples 215

DDDHDR: DDDVEC ;Address of DD display program to draw line.
LDDVEC ;Length of display program.

DDDVEC: CW FNCN,27,CHNL,0,FNCN,27 ;Graphics mode, own channel.
CW COLM,1,HILIN,27,LOLIN,0 ;Column 1, Line 560 (2*270).
REPEAT =13,<
BYTE (8)377,377,377,377 (4)2 ;Graphics word, all bits on.
> ;Draw a horizontal line =52 graphics bytes long.
CW EXCT,0,FNCN,27,FNCN,27 ;Execute to write out line.
0 ;End of DD program to draw a line.
LDDVEC←←.-DDDVEC

IIIHDR: IIIVEC ;Address of III display program to draw vector.
LIIVEC ;Length of display program.

IIIVEC: 0 ;All III programs must start with unused word.
BYTE (11)<-777>,<-400> (3)2,3 (2)1,2 (4)6
;Draw invisible absolute vector to left margin near bottom.
BYTE (11) 1777,0 (3)2,3 (2)0,0 (4)6
;Draw visible relative vector to right margin.
LIIVEC←←.-IIIVEC ;Length of program to draw III vector.

END DISPLA

14.3 Example of Using Interrupts

Here is a sample program that enables interrupts on the typing of ESC
I and on the receiving of a letter through the inter-job mail system
(see Section 7).

TITLE INTERRUPT EXAMPLE

A←1

INTMAIL←←4000 ;Interrupt bit for letter received.
INTTTI←←4 ;Interrupt bit for ESC I typed

INTSAM: RESET ;A good beginning.
;Note that RESET clears all interrupt enablings.
14.3 Example of Using Interrupts Examples 216

MOVEI A,INTRPT ;Set up address of routine to
MOVEM A,JOBAPR↑ ; handle interrupts.
;The symbol JOBAPR is EXTERNed by the ↑.

SETZM ESCIFG ;Initialize ESC I flag.
MOVSI A,INTMAIL!INTTTI;Interrupt bits we want to enable.
INTENB A, ;Enable interrupts for these bits.

<here is main program> ;Occasionally the main program will
... ; test ESCIFG and clear it and take
; appropriate action if it is set.
EXIT ;End of main program.

INTRPT: MOVS A,JOBCNI↑ ;Get bit which is cause of interrupt.
CAIN A,INTMAIL ;Did we get a letter?
JRST DOMAIL ;Yes. Go process it.
CAIN A,INTTTI ;Did user type ESC I? (He must have.)
SETOM ESCIFG ;Set flag to tell user-level process
; that ESC I has been typed.
DISMIS ;Dismiss the interrupt.

DOMAIL: SRCV LETTER ;Skip and read letter if one there.
DISMIS ;No letter (can't happen). Go home.
MOVE A,LETTER ;Get first word of letter.
CAME A,CODE ;See if letter has right format.
DISMIS ;Wrong format. Someone unknown
; has sent us a letter--ignore it.

<process letter here> ;Interrupt-level process must not
... ; go into wait state or take more
; than 8 ticks (8/60s sec) to finish.
DISMIS ;Dismiss the interrupt.

LETTER: BLOCK =32 ;Block for holding received letter.
CODE: SIXBIT /INTSAM/ ;Some special code to ensure we
; process only reasonable letters.

ESCIFG: 0 ;Flag indicating if ESC I was typed.

END INTSAM
Appendix 1 III Display Processor 217

APPENDIX 1

III DISPLAY PROCESSOR

The III display processor is itself a small computer. The
instructions that it executes form the display. In order for a user
to use the display processor, he must compile display instructions
into his program and ask the system to give these instructions to the
display processor. See Section 4.1 and Section 4.4 for details on
getting the system to run your display program. This appendix
explains the instructions that can be executed by the III display
processor.

TSS Instruction

Test, set, and skip Opcode 12
_____________________________________________________________________
|0 7|8 15|16 23|24 30| 31 |32 35|
| RESET | SET | TEST | unused | I | 1010 |
|___________|____________|___________|___________|_______|__________|

A skip condition is generated if at least one of the eight flags is
on and the corresponding bit in the TEST field is on. If the
exclusive or of the skip condition and bit 31 is true, the next
instruction is skipped. The flags are then set or reset according to
the set and reset field. If both set and reset bits are on, the
corresponding flag is complemented. The flags are as follows:

BITS OCTAL FLAG MEANING

0,8,16 401002,,0 Control bit. This bit may be set,
reset, and tested but has no other
meaning to the processor.

1,9,17 200401,,0 Light pen flag. The bit is set if the
light pen is seen.

2,10,18 100200,,400000 Edge overflow flag. This bit is set if
the beam is ever positioned off the
screen by any means.

3,11,19 40100,,200000 Wrap-around flag. This bit is set if
overflow occurs in incremental vector
mode.
Appendix 1 III Display Processor 218

4,12,20 20040,,100000 Not running mask. If this bit is on,
the processor will interrupt if a halt
is executed. This bit cannot be set or
reset by this instruction.

5,13,21 10020,,40000 Light pen mask. If this bit is on, the
processor will interrupt if the light
pen flag comes on.

6,14,22 4010,,20000 Edge overflow mask. If this bit is on,
the processor will interrupt if the edge
overflow flag comes on.

7,15,23 2004,,10000 Wrap-around mask. If this bit is on,
the processor will interrupt if the
wrap-around flag comes on.

LVW Instruction

Long vector word Opcode 06
_____________________________________________________________________
|0 10|11 21|22 24|25 27|28| 29 |30 31|32 35|
| X | Y | BRT | SIZE | | M | T | 0110 |
|___________|___________|_________|_________|__|_____|_____|________|

The long vector word draws one vector with mode, type and brightness
as specified by the M, T, and BRT fields respectively. A 0 in the
BRT field indicates no change in brightness. 1 is the dimmest
intensity and 7 the brightest. The brightness affects all vectors
and characters until reset by another long vector word.

Mode 0 indicates relative mode and 1 indicates absolute mode. In
absolute mode, the new position is given by the X and Y components
relative to the center of the screen. In relative mode the
components are added to the current position to give the new
position.

TYPE MEANING

0 Visible.
1 End point.
2 Invisible.
3 Undefined, currently end point.

A visible vector is drawn from the current position to the new
position; the invisible vector moves the beam to the new position
Appendix 1 III Display Processor 219

without displaying; the end point vector moves the beam to the new
position and then displays a point.

The size field sets the character size. The selected size is used
for all characters until reset by another long vector word with a
non-zero character size field. The sizes are:

SIZE CHARS PER LINE LINES PER SCREEN

0 no change no change
1 128 (smallest chars)64
2 85 42
3 73 36
4 64 32
5 42 21
6 32 16
7 21 (largest chars) 10

SVW Instruction

Short vector word Opcode 02
_____________________________________________________________________
|0 6|7 13|14 15|16 22|23 29|30 31|32 35|
| dX1 | dY1 | T1 | dX2 | dY2 | T1 | 0010 |
|_________|_________|________|_________|_________|________|_________|

The short vector word always draws two vectors in relative mode. The
type of each vector is specified by the corresponding T field (see
the long vector word above). The high order bits of the dX and dY
fields are extended left to give 11-bit quantities.

CHR Instruction

Character word Opcode 1
_____________________________________________________________________
|0 6|7 13|14 20|21 27|28 34| 35 |
| character | character | character | character | character | |
| 1 | 2 | 3 | 4 | 5 | 1 |
|___________|___________|___________|___________|___________|_______|

The character word displays the five characters in order from left to
right with automatic spacing. All characters are displayed as
printed on the line printer with the following exceptions:
Appendix 1 III Display Processor 220

CODE III CHARACTER

011 None.
013 Integral sign.
014 Plus-or-minus sign.
177 Backslash.

JMP Instruction

Jump Opcode 20
_____________________________________________________________________
|0 17|18 30|31 35|
| A | unused | 10000 |
|_________________________________|_____________________|___________|

The processor jumps to location A and continues executing.

HLT Instruction

Halt Opcode 00
_____________________________________________________________________
|0 17|18 30|31 35|
| unused | unused | 00000 |
|_________________________________|_____________________|___________|

The processor stops with its MA pointing to the location following
the HALT. The not running flag is turned on.

JMS Instruction

Jump to subroutine and save Opcode 04
_____________________________________________________________________
|0 17|18 31|32 35|
| A | unused | 0100 |
|_________________________________|______________________|__________|

The JMS instruction is not allowed in user III programs, but its
description is included here for completeness.
Appendix 1 III Display Processor 221

The following word of information is written into location A:

_____________________________________________________________________
|0 17|18 22|23 30|31 35|
| MA | CPC | unused | 10000 |
|_________________________________|____________|__________|_________|

where CPC is the contents of the CPC buffer register. This register
is loaded whenever the processor discovers an interrupt condition
while processing a character word or short vector word. It is set to
the number of the character being displayed (0-4) or the number of
the vector of the short vector word (0-1). It is reset by a CONO
430, with the clear flags bit on.

The following information is written in location A+1:

_____________________________________________________________________
|0 10|11 21|22 24|25 27|28 35|
| X | Y | BRT | SIZE | FLAGS |
|_____________|_____________|___________|___________|_______________|

Here are the meanings of the flag bits (see also the TSS instruction
above).

BITS OCTAL MEANING

28 0,,200 Control bit.
29 0,,100 Light pen flag.
30 0,,40 Edge overflow flag.
31 0,,20 Wrap around flag.
32 0,,10 Wrap around mask.
33 0,,4 Light pen mask.
34 0,,2 Edge overflow mask.
35 0,,1 This bit is always 1.

After storing the above words at A and A+1, the program continues
executing at A+2.

Note that the word stored in A is in the form of a jump instruction.
This permits the subroutine to return by jumping to A.
Appendix 1 III Display Processor 222

JSR Instruction

Jump to subroutine Opcode 24
_____________________________________________________________________
|0 17|18 30|31 35|
| A | unused | 10100 |
|_________________________________|_____________________|___________|

The JSR instruction saves a PC word into location A and then executes
code from location A+1. The PC word is in the same format as the
word stored in location A by the JMS instruction. The word is a jump
instruction so that the subroutine return can be simply a jump to A.

SAVE Instruction

Save Opcode 64
_____________________________________________________________________
|0 17|18 29|30 35|
| A | unused | 110100 |
|_________________________________|_____________________|___________|

The save instruction saves a position word in location A. This word
is in the same format as the word put into A+1 by the JMS instruction
and is in the correct format to be used by the REST instruction
below.

REST Instruction

Restore Opcode 14
_____________________________________________________________________
|0 17|18 29| 30 | 31 |32 35|
| B | unused | P | F | 1100 |
|_________________________________|____________|_____|_____|________|

The contents of location B are assumed to be in the format of the
word stored in location A+1 by a JMS or the word stored in location A
by a SAVE. If bit 30 is a 1, the X and Y position registers and the
size and brightness registers are reloaded from the corresponding
fields of this word. If bit 31 is a 1, the flags are restored.
Appendix 1 III Display Processor 223

SEL Instruction

Select (displays) Opcode 10
_____________________________________________________________________
|0 11|12 23|24 31|32 35|
| SET | RESET | unused | 1000 |
|____________________|_____________________|_______________|________|

If any of bits 0:11 (777700,,0 bits) are on, the corresponding
displays are selected. If any of bits 12:23 (77,,770000 bits) are
on, the corresponding displays are deselected. If both the select
and deselect bits are on for a given display, the state of selection
of that display will be complemented. Note that we have only 6 III
displays at Stanford; only bits 0:5 (770000,,0 bits) and 12:17 (77,,0
bits) are relevant in the SET and RESET fields.
Appendix 2 Data Disc Display System 224

APPENDIX 2

DATA DISC DISPLAY SYSTEM

The Data Disc display system uses a =64-track disc rotating at =60
r.p.s. to store TV images. The terminals used with this system are
standard television monitors. Each picture on the disc uses one
CHANNEL, which is two disc tracks. The tracks are switched
alternately every 60th of a second--one track for each field of the
standard television raster. Characters and graphics are sent to a
one-line buffer and then commanded to be written. Characters must be
written twice; once for each field.

There is an interface that takes display instructions from main
memory and sends data to the Data Disc. The display instructions are
used to change the pictures stored on the disc. A user can have his
own display programs executed by the Data Disc interface by using the
UUOs explained in Section 4.4; see also Section 4.2. This appendix
describes the display instructions, how they are handled by the
interface and their effects on Data Disc pictures.

The Data Disc system itself operates in two modes: text and graphics.
In text mode, each byte sent to the Data Disc is interpreted as a
character and will be displayed in the current column on the current
line; each column position is one character wide (6 bits wide in
single width character mode, 12 bits wide in double width character
mode). Characters must be written on the disk twice, once for each
track of the given channel. In graphics mode, each byte is
interpreted as eight bits to be written on the disk exactly as sent.
The bits are written on the current line at the current column
position. Each column position in graphics mode is 8 bits wide.

Normally, in both graphics and text modes data is sent to the Data
Disc line buffer and is not written onto the disc until an execute is
received by the Data Disc system. It is possible, however, to write
directly onto the disc without use of the line buffer. See the Write
Directly command in the command word description below.

Now here are the display instructions which the interface will
accept.
Appendix 2 Data Disc Display System 225

Text Word

Text word Opcode 1
___________________________________________________________
|0 6|7 13|14 20|21 27|28 34| 35|
| chr1 | chr2 | chr3 | chr4 | chr5 | 1 |
|__________|____________|__________|__________|_________|___|
| | | | | | | | | | | | |

A text word causes the interface to send five bytes to the disc's
line buffer. Tabs (011) and backspaces (177) are ignored unless
preceded by a backspace, in which case a special character is sent to
the line buffer (e.g., a small "tb" will be printed for 177&011).
Nulls are always ignored. Carriage return and linefeed are specially
processed to do the right thing: If any characters have been
transmitted to the line buffer since the last execute command (see
command word below), an execute is generated. (Execute causes the
line buffer to be written onto the disc.) Carriage return then
causes a select to column 2, and linefeed increments the line address
by 14. (If you are displaying double-height text, then each line
should be ended with a carriage return and TWO linefeeds in order for
subsequent lines to be positioned properly.) Both carriage return
and linefeed print special characters instead of the above functions
when preceded by a 177. Note: The Data Disc must be in text mode for
the bytes sent to it to be written onto the disc as text. In
graphics mode, these same bytes will be written as graphic bits.

Graphics Word

Graphics word Opcode 02
___________________________________________________________
|0 7|8 15|16 23|24 31|32 35|
| byte 1 | byte 2 | byte 3 | byte 4 | 02 |
|____________|_____________|____________|____________|______|
| | | | | | | | | | | | |

A graphics word causes the interface to send 4 8-bit bytes directly
to the disc's line buffer with no modification. Note: The Data Disc
must be in graphics mode for the bytes sent to it to be written onto
the disc as graphics bits. In text mode, these same bytes will be
written as characters.
Appendix 2 Data Disc Display System 226

Halt Instruction

Halt Opcodes 0, 40, 60
___________________________________________________________
|0 29|30 35|
| unused | X0 |
|_________________________________________________|_________|
| | | | | | | | | | | | |

A halt stops the interface, terminating the display program.

Jump Instruction

Jump Opcode 20
___________________________________________________________
|0 17|18 29|30 35|
| jump address | unused | 20 |
|_____________________________|___________________|_________|
| | | | | | | | | | | | |

A jump word causes the interface to take subsequent display
instructions starting at the address contained in the left half of
the jump word.

No Operation

No-op Opcodes 06,16,26,36,46,56,66,76, 12,32,52,72
___________________________________________________________
|0 29|30 35|
| unused | XX |
|_________________________________________________|_________|
| | | | | | | | | | | | |

Opcodes ending in 6 or 12 have no function. The interface ignores
them and proceeds.

WARNING: Opcodes ending in 10 (10, 30, 50, 70), previously advertised
as no-ops, are not no-ops at all; they are actually command words,
although their use as such is not recommended because the 10 bit is
part of the third command code (OP 3 in the command word below).
Appendix 2 Data Disc Display System 227

Command Word

Command word Opcode 4
___________________________________________________________
|0 7|8 15|16 23|2426|2729|3032|3335|
| data 1 | data 2 | data 3 |op 1|op 2|op 3| 4 |
|____________|____________|_____________|____|____|____|____|
| | | | | | | | | | | | |

A command word causes the interface to send the Data Disc three
commands, as indicated above by "op 1," "op 2" and "op 3." Sent with
each command is an 8-bit data byte. The commands possible are as
follows:

COMMAND NAME MEANING

0 Execute Write the line buffer onto the
disc at the position previously
specified. The data byte is
irrelevant for this command.

1 Function code Load the function code register
with the given data byte. The
meanings of the bits in the
function code register are
explained below.

2 Channel select Select the channel specified in
the data byte for writing. If
the erase bit is on and the
graphics mode bit is set, the
channel selected is erased to
the background selected by the
dark/light bit. Only the first
channel select in a DD display
program has any effect.

3 Column select The data byte is loaded into the
column register and the line
buffer address register. This
sets the X-position of your
output. Column 0 is illegal and
will hang the controller.
Column =85 is the last column to
be displayed with normal size
characters; characters sent for
columns =86 through =128 are
flushed, over =128, you wrap
Appendix 2 Data Disc Display System 228

around. A column select greater
than =85 will also hang the
controller. The last graphics
column is =64 and columns
greater than that will hang the
controller.

4 High order line address The data byte is loaded into
the high order 5 bits of the
line address.

5 Low order line address The data byte is loaded into
the low order 4 bits of the line
address. Line range is from 0
to 737 (octal). Line addresses
between 740 and 777 cause
execute commands to be ignored.
Line addresses above 777 wrap
around.

6 Write directly Data is written directly on the
disc at the location previously
set up; the line buffer is not
used. The column address is
automatically incremented.
Executes are not necessary.

7 Line buffer address Data is loaded into the line
buffer address only. This
allows some of the line buffer
contents to be changed and the
rest retained. The first
character displayed will be the
one specified by the column
address, and the last character
will be the last one sent after
this command.
Appendix 2 Data Disc Display System 229

The 8-bit function code register, which is loaded by command 1 above,
has the following format:

Bit# 0 1 2 3 4 5 6 7
_______________________________________________________________
| | |single |nospace|2 wide | dark | write |graphic|
|unused |unused |height | (add) |(erase)| back |enable | mode | 1
|_______|_______|_______|_______|_______|_______|_______|_______|
| | |double | space | | light |display| text |
|unused |unused |height | (rep) |1 wide | back |direct | mode | 0
|_______|_______|_______|_______|_______|_______|_______|_______|
MSB | | LSB |

BITS OCTAL MEANING

2 040 Single height/double height. (Text mode
only.)
This bit determines what height
displayed characters will have. Single
height characters are 12 lines tall; 10
lines above the "base" line and 2 lines
below. The top line of the character
prints on the line addressed. This bit
has no effect in graphics mode. If you
are displaying double-height text, then
each line should be ended with a
carriage return and TWO linefeeds in
order for subsequent lines to be
positioned properly.

3 020 Space/nospace. (Text mode only.)
When this bit is on, each character
written is substituted on top of the
character previously written; when this
bit is off, the remainder of the line is
erased.

3 020 Additive/replacement. (Graphics mode
only.)
When this bit is on, only 1 bits are
written, ORed with the bits already
written; when this bit is off, 1's and
0's are written over previous data.
CAUTION: When replacing, the bits at the
beginning and end of the line segment
you are writing should be the same as
the previous data or bit lossage may
occur.
Appendix 2 Data Disc Display System 230

4 010 Double width/single width. (Text mode
only.)
This bit determines what width displayed
characters will have. With this bit on,
characters are 5 bits wide with a 0 bit
on the end (total 6 bits); when this bit
is off, characters are =10 bits wide
with two 0 bits on the end.
CAUTION: When using double width
characters, do not exceed =43 characters
in a line or the controller will hang.
Double width characters often fail to
get displayed correctly anyway.

4 010 Erase. (Graphics mode only.)
If this bit and the graphics mode bit
are on, a channel select will cause the
screen to be erased to the background
indicated by the dark/light bit below.

5 004 Dark/light.
When this bit is on, an erase causes the
screen to go dark and characters and
graphic 1 bits are displayed as light.
When this bit is off, an erase makes the
background light and characters and
graphic 1 bits are displayed as dark.

6 002 Write/display directly.
When this bit is on, operations go to
the disc (normal mode). When off, data
is displayed once on the selected
channel and then goes away and previous
data remains on the disc.

7 001 Text/graphics mode.
When this bit is on, you are in graphics
mode; when it is off, you are in text
mode.
Appendix 3 PDP-10 Information 231

APPENDIX 3

GENERAL INFORMATION ABOUT THE PDP-10

The PDP-10 is a 36-bit word, single address machine. Normal
instructions (excluding I/O instructions) take the following form.

BITS OCTAL MEANINGS OF FIELDS IN AN INSTRUCTION
WORD

0:8 777000,,0 Instruction code.
9:12 740,,0 Accumulator.
13 20,,0 Indirect bit.
14:17 17,,0 Index register if non-zero.
18:35 0,,777777 Memory address.

For I/O instructions, the following format is used:

BITS OCTAL MEANINGS OF FIELDS IN I/O INSTRUCTIONS

0:2 700000,,0 This field is a 7 in all I/O instructions.
3:9 77400,,0 Code of I/O device.
10:12 340,,0 I/O instruction code.
13:35 37,,777777 Same as in normal instructions.

Machine I/O instructions are generally privileged in that only the
monitor is allowed to issue such instructions. The opcodes
corresponding to these instructions trap to the monitor, which
normally interprets them as UUOs. However, the user is permitted to
give machine I/O instructions when he is in IOT-USER mode, which is
described below.

For every instruction, an effective address calculation is carried
out in the following manner using bits 13:35 of the instruction. If
the index register field (bits 14:17) is non-zero, the contents of
the specified index register are added to the memory address found in
bits 18:35 of the instruction. Then if the indirect bit (bit 13) is
0, this result is the effective address for the instruction. If the
indirect bit is 1, then another word is picked up from the location
specified by the result so far. Then the effective address
calculation starts over using bits 13:35 of this new word. This
process continues until the indirect bit in some word used in this
calculation is 0; the address (including any indexing) specified by
that word is then the effective address of the instruction.
Appendix 3 PDP-10 Information 232

PC Flags

The PDP-10 has several flags that indicate the state of the program
running. These flags are commonly called the PC flags because their
values are stored in the left half of the PC word stored by the
PUSHJ, JSR and JSP instructions. The PC itself is stored in the
right half of this PC word. The bit positions and meanings of the
flags are explained below. For further detail, see the PDP-10
instruction manuals.

Note that there are no flags in bits 13:17; these bits are always
stored as zero in the PC word so that when the PC word is addressed
indirectly neither indexing nor further indirecting will take place.

BITS OCTAL MEANINGS OF FLAGS IN THE PC WORD

0 400000,,0 Overflow. An arithmetic operation has
resulted in an incorrect result because
of some kind of overflow.

1 200000,,0 Carry 0. An arithmetic operation has
caused a carry out of bit 0. This does
not necessarily indicate an overflow
condition.

2 100000,,0 Carry 1. An arithmetic operation has
caused a carry out of bit 1. This also
does not necessarily indicate an
overflow condition.

3 40000,,0 Floating overflow. A floating point
instruction has resulted in an incorrect
result because of some kind of overflow
or underflow.

4 20000,,0 Byte-increment suppression. The next
ILDB or IDPB instruction will be
executed without incrementing the byte
pointer. This flag is set when an ILDB
or IDPB instruction is interrupted after
the byte pointer has been incremented
but before the byte has been moved.
This flag can also be set by a user
program with the "JRST 2," instruction.

5 10000,,0 User mode. The processor is in user
mode.
Appendix 3 PDP-10 Information 233

6 4000,,0 User in-out. The processor is in
IOT-USER mode. This mode is explained
below.

11 100,,0 Floating underflow. The exponent of the
result of a floating point operation was
less than -128 (decimal).

12 40,,0 No divide. A division operation was not
carried out because either the divisor
was zero or an overflow would have
resulted.

IOT-USER Mode

On the PDP-10, usually only the monitor is allowed to use the
machine's I/O instructions. In user programs, the opcodes (700:777)
of these instructions are usually interpreted as UUOs. However,
there exists a special mode, called IOT-USER mode, in which the
opcodes 700:777 are executed not as UUOs but as machine I/O
instructions.

A user program can get into IOT-USER mode by giving the EIOTM UUO
(see page 149), which does nothing but put you into this mode. Also,
an interrupt-level process will be started up in IOT-USER mode after
a new style interrupt if bit 6 (the 4000,,0 bit) is on in JOBAPR; see
Section 9. Finally, spacewar processes are always started up in
IOT-USER mode; see Section 8.

The simplest method for getting out of IOT-USER mode, whether at
user, spacewar or interrupt level, is to execute a

JRST 2,@[.+1]

This turns off all of the PC flags, except the user-mode flag. See
the JRST instruction in the PDP-10 manuals and note that DEC calls
IOT-USER mode "user in-out".

In summary, opcodes 700:777 are treated as UUOs unless the program
executing such instructions is in IOT-USER mode, in which case these
opcodes are machine I/O instructions.
Appendix 3 PDP-10 Information 234

Text Representations

There are several common representations used for storing text on the
PDP-10. These include ASCII, ASCIZ, ASCID and SIXBIT. In each of
these four representations, characters are stored left-justified in a
block of one or more words. The octal codes for characters are given
in Appendix 7.

ASCII In this representation 7-bit characters are packed
5 to a word with the low order bit (bit 35--the
0,,1 bit) always being zero. A word count or
character count is needed to determine the length
of an ASCII string.

ASCIZ This is the same as ASCII except that a null (zero)
byte follows the last character in the string to
mark its end.

ASCID This is the same as ASCII except that the low order
bit of each word is always a one.

SIXBIT This representation packs 6-bit characters 6 to a
word. The characters representable in SIXBIT are
those with ascii representations from 40 to 137.

Assembler Features Relevant to this Manual

Here is an abbreviated list of PDP-10 assembler features, including
those used in the UUO writeups in this manual.

1. The form "[...]" is a literal whose value is the address at which
the code and/or data specified by "..." is placed in the program.
The code/data can consist of any number of words and can include
other literals.

2. The form "A,,B" represents a word whose left half contains the
value A and whose right half contains the value B. This is
equivalent to the form "XWD A,B".

3. The form "IOWD A,B" is exactly equivalent to the form "-A,,B-1".

4. The forms "ASCII /.../", "ASCIZ /.../", "ASCID /.../" and
"SIXBIT /.../" represent blocks of words containing the string "..."
in the ASCII, ASCIZ, ASCID and SIXBIT representations respectively.
See these representations above.
Appendix 4 Job Data Area 235

APPENDIX 4

JOB DATA AREA

The first 140 words of each core image are reserved for storage of
various parameters for that job. This block is called the user's Job
Data Area. The data here can be examined by the user, and he can
change some of it directly simply by storing new values in the
appropriate words.

Part of this data, however, is important to the system and is
protected from any attempt by the user to change it. In particular,
the block from JOBHCU to JOBPFI (see table below) is copied into the
monitor when the job is run so that the user cannot change it. When
the job is not running, this block is stored back in the user's job
data area to conserve space in the system.

References to locations in the job data area should be by their
symbolic names rather than by their absolute addresses. It is
possible that some of these locations might be moved around, and if
that happens, programs that refer to these locations symbolically
will need only to be reloaded. All of the symbols for these words
are defined in a system library file; their definitions will
automatically be retrieved from there by the LOADER if the symbols
are declared EXTERNAL.

The table below explains the names and uses of the locations in the
job data area.

WORD SYMBOL EXPLANATION

0 JOBAC The user's accumulators are stored here over
UUO calls.

20 JOBDAC The user's accumulators (whether Exec mode or
user mode) are stored here when a clock trap
occurs.

40 JOBUUO User UUOs (opcodes 001:037) encountered are
stored here after the effective address
calculation has been done. See Section 1.4.

41 JOB41 The instruction in this location is executed
whenever a user UUO (opcodes 001:037) is
encountered. This instruction is often a JSR
to the user's UUO-handling routine. See
Section 1.4.
Appendix 4 Job Data Area 236

43 JOBENB The user's APR trap enablings (old style
interrupt enablings) are stored here. See
Section 9.

44 JOBREL The job's protection constant is stored here.
This is the highest address in the user's
core image (excluding any upper segment).

45 This is the first of several words used for
temporary storage by the system.

71 JOBINT If this word is non-zero, it specifies the
address in the user's core image of a block
of three words to be used in place of JOBCNI,
JOBTPC and JOBAPR, respectively, for new
style interrupts. See Section 9.

72 JOBHCU (Also know as JOBPRT.) The number of the
highest I/O channel in use by this job is
stored here. This is the first location of
the block copied into the system when the job
is run.

73 JOBPC Your program counter is stored here when your
program is not running.

74 JOBDDT If DDT or RAID is present in your core image,
its starting address is stored here. When
you type the DDT monitor command, your
program is started at the address specified
in this word, unless this word contains zero.
Also, when RAID is present, bits 0:12 (the
777740,,0 bits) of this word hold the version
number of RAID. This is first word written
into a dump file by the SAVE monitor command.

75 JOBJDA This is the first word of a 20-word block in
which are stored the system addresses of the
device data blocks (DDBs) for the devices you
have open on the 20 logical I/O channels.
The address of the DDB for channel 6, for
instance, is stored in JOBJDA+6.

114 JOBPFI This is the last word of the 20-word block
starting at JOBJDA and is also the last word
of the block (starting at JOBHCU) that is
copied into the system when you run.

115 JOBHRL The right half of this word contains the
Appendix 4 Job Data Area 237

highest address in your upper segment (e.g.,
401777 for a 1K upper), and the sign bit
(400000,,0 bit) is on if your upper is write
protected. If you have no upper, this word
is zero.

116 JOBSYM A pointer to your symbol table is placed
here. If you have no symbols in your core
image, this word is zero. Otherwise, the
left half of this word contains the negative
of the number of symbols in the table, and
the right half contains the address of the
first word of the table.

117 JOBUSY A pointer to the table of undefined globals
encountered is placed here by the LOADER.
This word has the same format as JOBSYM above
(i.e., -<word count>,,<table>). If there
were no undefined globals, the left half of
this word will contain zero.

120 JOBSA The right half of this word contains the
starting address of your program. The START
and CSTART monitor commands cause your
program to be started at that address (unless
it is zero). The left half of this word
contains the address of the first location
above your symbol table (or program if no
symbol table). The RESET UUO (see page 139)
causes this number to be stored in JOBFF (see
below).

121 JOBFF The address of the first free (unused)
location in your core image is stored here.
The words from that address up to that in
JOBREL are not used. Whenever the system
sets up an I/O buffer for you, it is put at
the address specified by JOBFF and JOBFF is
then increased to point to the first word
beyond the buffer. The RESET UUO causes
JOBFF to be reset to the value stored in the
left half of JOBSA (see above).

122 JOBS41 The contents of JOB41 (see above) are stored
here just before the core image is written
into a dump file by a SAVE or SSAVE monitor
command or by the SWAP UUO. JOB41 is
restored from this word when the file is read
by a GET, RUN or R command or by the SWAP
UUO.
Appendix 4 Job Data Area 238

123 JOBEXM This is a temporary cell used by the EXAMINE
and DEPOSIT monitor commands.

124 JOBREN This word contains the address at which the
program should be started when the REENTER
monitor command is given. A zero in this
word means REENTER will not work.

125 JOBAPR This word should contain the address at which
you wish your interrupt routine started when
an interrupt occurs. See Section 9.

126 JOBCNI When an interrupt occurs, a bit indicating
the cause is stored here. See Section 9.

127 JOBTPC When an interrupt occurs, the program counter
word is stored here before control is given
to your interrupt routine. See Section 9.

130 JOBOPC When you start the program with a START,
CSTART, DDT or REENTER monitor command, the
program counter word (picked up from JOBPC)
is stored here.

131 JOBCHN This word is used for FORTRAN chaining.

132 JOBFDV This word is used for temporary storage by
the FINISH command.

133 JOBCOR This word is used for temporary storage by
the SAVE and GET commands.

134 HINAME The name of your upper segment, if any, is
stored here just before your core image is
written onto a dump file by a SAVE or SSAVE
monitor command or by the SWAP UUO.

135 HILOC The location within the dump file of your
upper segment is stored here prior to writing
a dump file with the SSAVE monitor command.

140 JOBDA This is the first word in your core image
that is not part of the job data area.
Appendix 5 Monitor Pointers 239

APPENDIX 5

LOCATIONS OF USEFUL POINTERS IN THE MONITOR

The table below lists the contents of some absolute locations in the
monitor. Most of these locations contain pointers to system tables
that user programs occasionally need to examine. Any word in memory
may be examined by use of either the PEEK UUO (see page 105) or the
SETPR2 UUO (see page 103).

To get the address of a particular job's entry in a job table, add
the job number to the base address of the table.

WORD CONTENTS EXPLANATION

210 JBTSTS This is the address of the job table of
status words. The bits in each entry are
explained with the JBTSTS UUO on page 101.

211 PRJPRG This is the address of the job table of
project-programmer names.

212 JBTSWP This is the address of the job table of
swapper data. The left half (bits 0:17--the
777777,,0 bits) of each entry contains the
logical band number used to swap this job.
Bits 18:26 (0,,777000 bits) contain the size
of the job (in 1K blocks) as stored on the
disk. Bits 27:35 (0,,777 bits) contain the
size of the job (in 1K blocks) as it will
appear when it is swapped in.

213 SPWGO This is the address of the job table of
PDP-10 spacewar processes. The right half
(bits 17:35--0,,777777 bits) of each entry
contains the user-specified starting address
of the spacewar process. Bits 14:17 (17,,0
bits) contain the number of ticks between
startups, and bits 10:13 (36,,0 bits) contain
the number of ticks until the next startup.
This word is zero for jobs that do not have
PDP-10 spacewar processes running. See
Section 8.

214 TTIME This is the address of the job table of total
run times (in ticks). The time for job 0 is
Appendix 5 Monitor Pointers 240

the null time (idle time) since the last
system reload or restart.

215 UPTIME This is the address of a word that contains
the length of time in ticks since the last
system reload or restart.

216 CORMAX This is the address of a word that contains
the largest size (in 1K blocks) a user
program can be and still fit in core.

217 DEVLST This is the address of the header word for
the list of all device data blocks (DDBs).
The left half of the header word contains the
address of the first DDB. DDBs are described
in Appendix 6.

220 TTYTAB This is the address of the table of pointers
to TTY DDBs. The entry for a TTY in use
contains the TTY line number in the left half
and a pointer to the TTY's DDB in the right
half. The entry for a TTY not in use is
zero. Index into this table with the TTY
line number.

221 BYTE (9) SCNNUM,DPYNUM,DDNUM,PTYNUM These four
quantities are the numbers of 1) teletype
lines, 2) III display lines, 3) Data Disc
display lines and 4) pseudo-teletype lines,
respectively.

222 JOBN-1 This is the highest possible job number.

223 JBTADR This is the address of the job table of
protection-relocation constants. The left
half of each entry contains the job's
protection, which is the highest location
addressable in the job (not counting any
upper segment). The right half of each entry
contains the job's relocation, which is the
physical memory address where the job's core
image is actually located. When a job is
swapped out, its entry in this table is zero.

224 JBTQ This is the address of the job table of
entries in the job queues. The queues are
circular with each entry containing a forward
pointer in the right half and a backward
pointer in the left half. The pointers are
Appendix 5 Monitor Pointers 241

all relative to JBTQ: a pointer that is
positive points to another job's entry in the
table; a pointer that is negative points to
the queue's header word, which itself is just
another entry in the circular queue and which
contains both forward and backward pointers.
The magnitude of a negative pointer indicates
the number of the queue the entry is in.

225 JOBNAM This is the address of the job table of
sixbit job names.

226 JOB This is the address of a word that contains
the number of the currently running job.

227 CONFIG This is the address of an ASCIZ string that
gives the title of the current system.

230 SP2GO This is the address of the job table of PDP-6
spacewar processes. The format of this table
is the same as that of the SPWGO table; see
word 213 above.

231 JOBQUE This is the address of the job table of queue
numbers. Each entry in this table contains
either the queue number or the negative of
the queue number for the particular job.

234 NQUES This is the number of different queues. The
queues are numbered from 1 to this number.

235 QNAMS This is the address of a table of the ASCII
names of the various queues. Index into this
table with the queue's number.

236 JBTLIN This is the address of the job table of
attached terminals. The entry in this table
will be -1 for a detached job. For an
attached job the entry will contain the TTY
line number in the right half and the
permanent TTY line characteristics in the
left half. There may be bits on for
non-permanent characteristics, but these bits
are not kept up to date in this word. See
LINTAB in word 302 below for the current line
characteristics; see also the GETLIN UUO on
page 45.

237 LETAB This is the address of the table of pointers
Appendix 5 Monitor Pointers 242

to the displays' line editor headers. The
right half of each entry contains a pointer
to the free storage block for that display.
The left half holds various flags used by the
line editor. When a display is not in use,
its entry here is zero. Index into this
table with the number of the display line
minus 20.

250 JBTKCJ This is the address of the job table of
kilo-core-jiffies (KCJs) used by each job. A
jiffie is a tick, i.e., 1/60th of a second.
One KCJ represents a job running for one tick
with 1K of core.

251 JBTBTM This is the address of the job table of login
times. Each entry in this table contains the
date and time when the particular job logged
in, with the date (in system date format) in
the left half and the time (in seconds after
midnight) in the right half.

257 SHFWAT This is the address of a word that contains
the number of the next job to be shuffled in
core.

265 SYSTOP This is the address of a word that contains
the physical address of the first word in
memory that can be allocated to user
programs.

266 CORTAB This is the address of a table that indicates
the usage of each 1K block of core. The
entries in this table are 9-bit bytes packed
4 to a word. The entry for a given block
contains either 1) the number of the job
occupying the block, 2) a 101 if the block is
part of the system, 3) a 105 if the block is
part of free storage or 4) a 0 if the block
is unused.

270 PTYJOB This is the address of the table of owners of
pseudo-teletypes (PTYs). Each entry contains
the number of the job that owns that PTY.
Index into this table with the PTY line
number minus 121.

271 JBTPRV This is the address of the job table of
privileges.
Appendix 5 Monitor Pointers 243

272 UCLLEN*1000+UCLDLN,,UCLTAB The right half of this
word contains UCLTAB which is the address of
the CALL UUO name table. This table is made
up of two parts. The first UCLDLN words
contain the names of DEC CALLs, and the next
UCLLEN-UCLDLN words contain the names of the
special Stanford CALLs (numbers from 400000
up). Thus the total length of the table is
UCLLEN, which is in bits 0:8 (777000,,0 bits)
of word 272; the length of the first part of
the table, UCLDLN, is in bits 9:17 (777,,0
bits) of word 272. The CALL names within
each part are in their expected order by
CALLI number.

273 DSKPPN This is the address of the job table of Disk
PPNs (ALIASes). If a job has no ALIAS, its
entry in this table is zero. Disk PPNs are
explained on page 17.

274 FTIME This is the address of the job table
containing each job's time last run. Each
entry contains the date and time when the
particular job was last run, with the date
(in system date format) in the left half and
the time (in seconds after midnight) in the
right half.

275 NJOBS This is the address of the job table that
gives the number of users for each upper
segment. Each entry contains the number of
jobs attached to the given upper segment.
Index into this table with the upper
segment's job number.

276 DSKOPS This is the address of the job table
containing the number of disk operations each
job has done. The entry for job 0 is the
total number of disk operations since the
system was reloaded.

277 INITIM This is the address of a word that contains
the date and time of the last system reload
or 203 restart. The date (in system date
format) is in the left half and the time (in
seconds after midnight) is in the right half.

300 -DISPL,,COMTAB COMTAB is the address of the table of
monitor commands names in sixbit, and DISPL
is the number of commands in that table.
Appendix 5 Monitor Pointers 244

302 LINTAB This is the address of the table of TTY line
characteristics. Each entry in this table
corresponds to a particular TTY. The TTY's
line characteristics are in the left half
(see the GETLIN UUO on page 45 for the
meanings of these bits). The right half is
used to store ESCAPE arguments (for TTYs that
are displays). Index into this table with
the TTY line number of interest.

303 ASTAB This is the address of the audio switch
connection table. There is a word here for
each display; index into this table with the
display's line number minus 20. The data in
each entry of this table is as follows (for
more details about the audio switch, see
Section 4.7):

BITS OCTAL VALUES OF FIELDS IN ASTAB ENTRY

0 400000,,0 One if a UUO is waiting for a
temporary connection to finish
on this display.
1 200000,,0 One if the current connection is
a temporary connection.
2 100000,,0 One if a page interruption is
happening at this display.
3 40000,,0 One if a delayed beep is
pending.
4 20000,,0 One if the permanent audio
channel is not page
interruptible.
5 10000,,0 One if the permanent channel is
not beep interruptible.
6:7 6000,,0 Beep disposition for temporary
channel.
8:9 1400,,0 Page disposition for temporary
channel.
10:13 360,,0 Temporary channel number.
14:17 17,,0 Permanent channel number.
18:35 0,,777777 Remaining duration of temporary
connection (0 for infinite).
Appendix 6 DDBs 245

APPENDIX 6

DEVICE DATA BLOCKS (DDBS)

For each device used, there is a Device Data Block (DDB) in the
system in which is kept a collection of data pertinent to the device.
Certain devices (including the disk, the IMP, and TTYs) do not have
DDBs when they are not in use; other devices' DDBs are permanently
built into the list. With sharable devices such as the disk, there
is a DDB for each user I/O channel with the device open.

All the DDBs are linked together in one big list. The header for
this list is located at DEVLST; the left half of the word at DEVLST
points to the first DDB. (The word DEVLST is pointed to by the word
at absolute memory address 217; see Appendix 5.)

The data common to all DDBs is explained below. Other data is device
dependent.

WORD NAME CONTENTS

0 DEVNAM This is the device's physical name in sixbit.

1 DEVCHR Bits 0:5 (770000,,0 bits) of this word
contain the number of the job the device
belongs to, or zero if the device is unused;
if this field contains zero and the device is
ASSIGNed (see the DEVCHR UUO on page 38),
then the device has been detached from the
system (probably for maintenance).
Bits 6:11 (7700,,0 bits) contain the current
hung time count down in seconds.
Bits 12:17 (77,,0 bits) contain the hung time
in seconds.
Bits 18:23 (0,,770000 bits) contain the unit
number for multiple unit devices like
dectapes and magnetic tapes.
Bits 24:35 (0,,7777 bits) contain the size in
words of the buffer this device uses.

2 DEVIOS This is the device's I/O status word. See
Section 2.6.

3 DEVSER The right half of this word contains the
address in the system of this device's UUO
dispatch table. The left half contains the
Appendix 6 DDBs 246

address of the next DDB in the list, or zero
if this is the last DDB.

4 DEVMOD This is the word returned by the DEVCHR UUO
(see page 38).

5 DEVLOG This is the device's logical name in sixbit,
if any.

6 DEVBUF The left half of this word contains the user
address of the output buffer header, if any.
The right half contains the user address of
the input buffer header, if any.

11 DEVFIL For directory devices like the disk and
dectapes, this word contains the sixbit name
of the file that is currently open, or zero
if no file is open.

12 DEVEXT For directory devices the left half of this
word contains the file name extension of the
file currently open.

13 FILPRO For disk files this word contains the
protection, mode and date/time written. For
dectape files this word contains the date
written. See the LOOKUP UUO on page 24.

14 FILPPN For disk files this word contains the
project-programmer name of the file currently
open.
Appendix 7 Stanford Character Set 247

APPENDIX 7

STANFORD CHARACTER SET

The table below gives the octal codes for characters in the Stanford
ascii character set. The octal code for a character is three digits
and is obtained for a character in the table by adding the label of
the character's row to the label of the character's column. For
example, the ascii code for "G" is 100+7, or 107.

To get the sixbit code for a character, find the ascii code and
subtract 40. Note that the only characters with sixbit
representations are those with ascii codes in the range 40:137.

The abbreviations used for special characters in the table are
explained below.

0 1 2 3 4 5 6 7

000 NUL ↓ α β ∧ ¬ ε π
010 λ TAB LF VT FF CR ∞ ∂
020 ⊂ ⊃ ∩ ∪ ∀ ∃ ⊗ ↔
030 _ → ~ ≠ ≤ ≥ ≡ ∨
040 SP ! " # $ % & '
050 ( ) * + , - . /
060 0 1 2 3 4 5 6 7
070 8 9 : ; < = > ?
100 @ A B C D E F G
110 H I J K L M N O
120 P Q R S T U V W
130 X Y Z [ \ ] ↑ ←
140 ` a b c d e f g
150 h i j k l m n o
160 p q r s t u v w
170 x y z { | ALT } BS

NUL (0) is a null.
TAB (11) is a tab.
LF (12) is a linefeed.
VT (13) is a vertical tab.
FF (14) is a form feed.
CR (15) is a carriage return.
SP (40) is a space.
ALT (175) is an altmode.
BS (177) is a backspace.
Appendix 8 UUOs by Number 248

APPENDIX 8

UUOS BY NUMBER

-----UUOs----- ----CALLIs---- ----CALLIs----
Opcode Name Number Name Number Name
040 CALL 0 RESET 400010 UFBGET
041 INIT 1 DDTIN 400011 UFBGIV
043 SPCWAR 2 SETDDT 400012 UFBCLR
047 CALLI 3 DDTOUT 400013 JBTSTS
050 OPEN 4 DEVCHR 400014 TTYIOS
051 TTYUUO 5 DDTGT 400015 CORE2
055 RENAME 6 GETCHR 400016 ATTSEG
056 IN 7 DDTRL 400017 DETSEG
057 OUT 10 WAIT 400020 SETPRO
060 SETSTS 11 CORE 400021 SEGNUM
061 STATO 12 EXIT 400022 SEGSIZ
062 GETSTS 13 UTPCLR 400023 LINKUP
063 STATZ 14 DATE 400024 DISMIS
064 INBUF 15 LOGIN 400025 INTENB
065 OUTBUF 16 APRENB 400026 INTORM
066 INPUT 17 LOGOUT 400027 INTACM
067 OUTPUT 20 SWITCH 400030 INTENS
070 CLOSE 21 REASSI 400031 INTIIP
071 RELEAS 22 TIMER 400032 INTIRQ
072 MTAPE 23 MSTIME 400033 INTGEN
073 UGETF 24 GETPPN 400034 UWAIT
074 USETI 25 TRPSET 400035 DEBREA
075 USETO 26 TRPJEN 400036 SETNM2
076 LOOKUP 27 RUNTIM 400037 SEGNAM
077 ENTER 30 PJOB 400040 IWAIT
31 SLEEP 400041 USKIP
32 SETPOV 400042 BUFLEN
701 DPYCLR 33 PEEK 400043 NAMEIN
702 PPIOT 34 GETLN 400044 SLEVEL
703 UPGIOT 35 RUN 400045 IENBW
704 UINBF 36 SETUWP 400046 RUNMSK
705 UOUTBF 37 REMAP 400047 TTYMES
706 FBREAD 40 GETSEG 400050 JOBRD
707 FBWRT 41 GETTAB 400051 DEVUSE
710 MAIL 42 SPY 400052 SETPR2
711 PTYUUO 43 SETNAM 400053 GETPR2
712 POINTS 44 TMPCOR 400054 RLEVEL
713 UPGMVE 400055 UFBPHY
714 UPGMVM 400000 SPWBUT 400056 UFBSKP
715 PGIOT 400001 CTLV 400057 FBWAIT
716 CHNSTS 400002 SETNAM 400060 UFBERR
717 CLKINT 400003 SPCWGO 400061 WAKEME
720 INTMSK 400004 SWAP 400062 GETNAM
721 IMSKST 400005 EIOTM 400063 SNEAKW
722 IMSKCL 400006 LIOTM 400064 SNEAKS
723 INTUUO 400007 PNAME 400065 GDPTIM
Appendix 8 UUOs by Number 249

----CALLIs---- ----TTYUUOs---
Number Name Number Name
400066 SETPRV 0, INCHRW
400067 DDCHAN 1, OUTCHR
400070 VDSMAP 2, INCHRS
400071 DSKPPN 3, OUTSTR
400072 DSKTIM 4, INCHWL
400073 SETCRD 5, INCHSL
400074 CALLIT 6, GETLIN
400075 XGPUUO 7, SETLIN
400076 LOCK 10, RESCAN
400077 UNLOCK 11, CLRBFI
400100 DAYCNT 12, CLRBFO
400101 ACCTIM 13, INSKIP
400102 UNPURE 14, INWAIT
400103 XPARMS 15, SETACT
400104 DEVNUM 16, TTREAD
400105 ACTCHR 17, OUTFIV
400106 UUOSIM
400107 PPSPY ----PTYUUOs---
400110 ADSMAP Number Name
400111 BEEP 0, PTYGET
1, PTYREL
---MAIL UUOs-- 2, PTIFRE
Number Name 3, PTOCNT
0, SEND 4, PTRD1S
1, WRCV 5, PTRD1W
2, SRCV 6, PTWR1S
3, SKPME 7, PTWR1W
4, SKPHIM 10, PTRDS
5, SKPSEN 11, PTWRS7
12, PTWRS9
----INTUUOs--- 13, PTGETL
Number Name 14, PTSETL
0, INTJEN 15, PTLOAD
1, IMSTW 16, PTJOBX
2, IWKMSK
3, INTDMP
4, INTIPI ----PPIOTs----
5, IMSKCR Number Name
0, PPSEL
----PGIOTs---- 1, PPACT
Number Name 2, DPYPOS
0, PGSEL 3, DPYSIZ
1, PGACT 4, PPREL
2, PGCLR 5, PPINFO
3, DDUPG 6, LEYPOS
4, PGINFO 7, PPHLD
INDEX 250

INDEX CLSR bit (20000,,0--IMP
connection status) 201
136 interface 192 CLSS bit (40000,,0--IMP
167 data channel 197 connection status) 201
: 6 CMWB bit (200000,,0--job status)
= 6 101
ACCTIM UUO (CALLI 400101) 96 compute time 97
ACTCHR UUO (CALLI 400105) 53 CONNECT to socket 204
activation table 46, 50 CONTROL and META keys 42, 59,
AD/DA converter 192 61
ADSMAP UUO (CALLI 400110) 83 control-C by PTYUUO, sending 61
ALIAS command 18 control-CR, disabling 50
APRENB UUO (CALLI 16) 131 COPY 16
ARPA network 199 CORE UUO (CALLI 11) 97
ascii character codes 247 CORE2 UUO (CALLI 400015) 90
ASCII, ASCID and ASCIZ creation date 24
representations 234 CSTART command 237, 238
ASSIGN command 34 CTLV UUO (CALLI 400001) 53
ATTSEG UUO (CALLI 400016) 90 CTROV bit (0,,1000--IMP status)
audio switch 81 201
bad retrieval 29 DART 16
BEEP UUO (CALLI 400111) 86 Data Disc channels 76
bit numbers 6 Data Disc display system 224
bits, groups of 6 Data Disc displays 66
bits, references to 6 data modes 8
bless host 207 data switches, PDP-10 console
buffer diagram 13 102
buffer header 11 date format, system 95
buffer pointers 12 date last dumped 156
buffer rings 11 DATE UUO (CALLI 14) 95
buffer rings, setting up 21 dates and times from UUOs 95
buffer sizes, nonstandard 22 DAYCNT UUO (CALLI 400100) 95
buffer-creating UUOs 21 DDBs 245
buffered mode 8 DDCHAN UUO (CALLI 400067) 77
buffers 12 DDT 148, 236
BUFLEN UUO (CALLI 400042) 23 DDT command 148, 238
CALL UUO (UUO 040) 3 DDTGT UUO (CALLI 5) 153
CALLI UUO (UUO 047) 3 DDTIN UUO (CALLI 1) 151
CALLIT UUO (CALLI 400074) 103 DDTOUT UUO (CALLI 3) 152
cameras, TV 195 DDTRL UUO (CALLI 7) 153
channel number 8 DDUPG UUO (PGIOT 3,) 75
channel use bits 37 DEASSIGN command 34
CHARACTER MODE 44 DEBREAK UUO (CALLI 400035) 125
character set 247 DEC UUOs 5
CHNSTS UUO (UUO 716) 37 DECIMAL 6
CLKINT UUO (UUO 717) 123 dectapes 179
clock interrupts 123 DELETE command 17
CLOSE UUO (UUO 070) 32 delete-protect bit (200--file
CLRBFI UUO (TTYUUO 11,) 49 protection) 17
CLRBFO UUO (TTYUUO 12,) 49 deleting files 26
INDEX 251

detached jobs 45 example of display programming
DETSEG UUO (CALLI 400017) 91 212
DEVCHR UUO (CALLI 4) 38 example of general I/O 210
device characteristics word 38 example of using interrupts 215
device data blocks 245 EXIT UUO (CALLI 12) 138
device I/O status word SEE I/O extended UUOs 2
device status word FAIL 3, 4
device names, logical and fast bands 133
physical 19 FBERP bit (0,,4000--job status)
device unit number, finding 40 102
DEVNUM UUO (CALLI 4000104) 40 FBINP bit (0,,10000--job status)
DEVUSE UUO (CALLI 400051) 39 102
directory files 156 FBREAD UUO (UUO 706) 135
disk error codes 29 FBWAIT UUO (CALLI 400057) 137
disk file record offset 157 FBWRT UUO (UUO 707) 136
disk files 155 file dumping 16
Disk PPN 17 file protection bits 16
disk, bad retrieval for 29 file's protection, mode written,
disk, full 29 and date/time written 24
DISMIS UUO (CALLI 400024) 114, filenames 16
124 filenames, changing 26
display output 65 files 16
display programming, an example files, creating 25
212 files, deleting 26
display programs 72 files, extending 35
displays, Data Disc 66 files, opening 23
displays, III 65 files, random access of 34
displays, resetting 76 files, updating 27
DMPBIT bit (0,,400--disk status) Font compile and select 173
158 Font Compiler 177
DPYCLR UUO (UUO 701) 76 full-character-set mode 47
DPYOUT 72 GARBIT bit (0,,200--disk status)
DPYPOS UUO (PPIOT 2,) 69 158
DPYSIZ UUO (PPIOT 3,) 69 GARBIT bit (0,,200--UDP status)
DSKPPN UUO (CALLI 400071) 18 190
DSKTIM UUO (CALLI 400072) 96 GCW 167
dump date for disk files 156 GDPTIM UUO (CALLI 400065) 154
dump mode 8, 10 GETCHR UUO (CALLI 6) 152
dump mode command lists 10 GETLIN UUO (TTYUUO 6,) 45
dump-never bit (400--file GETLN UUO (CALLI 34) 54
protection) 17 GETNAM UUO (CALLI 400062) 98
echo suppression for terminals GETPPN UUO (CALLI 24) 98
41, 47, 53, 63 GETPR2 UUO (CALLI 400053) 105
EIOTM UUO (CALLI 400005) 149 GETSEG UUO (CALLI 40) 153
ENTER UUO (UUO 077) 25, 190 GETSTS UUO (UUO 062) 36
ENTERs, long block 156 GETTAB UUO (CALLI 41) 153
ENTRB bit (0,,20000--channel glitch hold count 71
status) 37 glitches 69
escape characters by PTYUUO, Group Command Word 167
sending 59
INDEX 252

HDEAD bit (0,,2000--IMP status) INITB bit (0,,400000--channel
201 status) 37
hidden records 157 initializing a device 18
high segments SEE upper INPB bit (0,,10000--channel
segments status) 37
HNGTRP bit (0,,200--LPT status) INPUT UUO (UUO 066) 31
166 input/output SEE I/O
I/O byte pointer and byte count INSKIP UUO (TTYUUO 13,) 49
11 INTACM UUO (CALLI 400027) 123
I/O channels 8 INTCLK bit (200,,0--interrupt
I/O device status word 14, 36, bits) 118
54 INTDMP UUO (INTUUO 3,) 129
I/O Devices 155 INTENB UUO (CALLI 400025) 122
I/O status error bits 30 INTENS UUO (CALLI 400030) 123
I/O status testing and setting interrupt level 122
36 interrupt mask 127, 130
I/O UUOs, example sequence of 7 interrupt-wait wakeup mask 129
I/O, an example 210 interrupts pending 126
I/O, general 7 interrupts, an example 215
I/O, synchronous 15 interrupts, generating 126, 130
I/O, terminating 32 interrupts, new style 120
I/O, transferring data 30 interrupts, old style 130
I/O, TTY 41 interrupts, user 115
IBUFB bit (0,,200000--channel INTFOV bit (0,,100--interrupt
status) 37 bits) 120
ICLOSB bit (0,,2000--channel INTGEN UUO (CALLI 400033) 126
status) 38 INTIIP UUO (CALLI 400031) 150
IENBW UUO (CALLI 400045) 126 INTIMS bit (20,,0--interrupt
III display processor 217 bits) 118, 202
III displays 65 INTINP bit (10,,0--interrupt
illegal memory reference 119 bits) 118, 202
ILM bit (0,,20000--interrupt INTINR bit (100,,0--IMP
bits) 119 connection status) 201
IMLACs, sending special commands INTINR bit (100,,0--interrupt
to 51 bits) 118, 202
IMP 199 INTINS bit (40,,0--IMP connection
IMSKCL UUO (UUO 722) 127 status) 201
IMSKCR UUO (INTUUO 5,) 130 INTINS bit (40,,0--interrupt
IMSKST UUO (UUO 721) 127 bits) 118, 202
IMSTW UUO (INTUUO 1,) 128 INTIPI UUO (INTUUO 4,) 130
IN UUO (UUO 056) 30 INTIRQ UUO (CALLI 400032) 126
INBFB bit (0,,400--channel INTJEN UUO (INTUUO 0,) 128
status) 38 INTMAIL bit (4000,,0--interrupt
INBUF UUO (UUO 064) 21 bits) 117
INCHRS UUO (TTYUUO 2,) 44 INTMSK UUO (UUO 720) 127
INCHRW UUO (TTYUUO 0,) 43 INTORM UUO (CALLI 400026) 123
INCHSL UUO (TTYUUO 5,) 45 INTOV bit (0,,10--interrupt bits)
INCHWL UUO (TTYUUO 4,) 44 120
information UUOs 95 INTPAR bit (400,,0--interrupt
INIT UUO (UUO 041) 20 bits) 118
INDEX 253

INTPTI bit (1000,,0--interrupt IOWC bit (0,,20--I/O status)
bits) 118 12, 15
INTPTO bit (10000,,0--interrupt IOWD 10, 234
bits) 117 IWAIT UUO (CALLI 400040) 125
INTQXF bit (2,,0--interrupt bits) IWKMSK UUO (INTUUO 2,) 129
118 JACCT bit (100000,,0--job status)
introduction 1 101
INTSHD bit (40000,,0--interrupt JBTSTS UUO (CALLI 400013) 101
bits) 117 JERR bit (20000,,0--job status)
INTSHW bit (100000,,0--interrupt 101
bits) 117 JLOCK bit (0,,100000--job status)
INTSWD bit (200000,,0--interrupt 102
bits) 117 JLOG bit (10000,,0--job status)
INTSWW bit (400000,,0--interrupt 101
bits) 117 JNA bit (40000,,0--job status)
INTTTI bit (4,,0--interrupt bits) 101
118 job data area 235
INTTTY bit (20000,,0--interrupt job information 97
bits) 117 job name 98, 100
INTUUO UUO (UUO 723) 128 job number 98
INTWAIT bit (2000,,0--interrupt job status word 101
bits) 117 job using a device 39
INWAIT UUO (TTYUUO 14,) 49 JOBAPR 115, 121, 131, 238
IOACT bit (0,,10000--I/O status) JOBCNI 115, 116, 120, 130, 150,
15 238
IOBKTL bit (0,,40000--I/O status) JOBDDT 148, 236
14, 30, 179 JOBENB 236
IOBOT bit (0,,4000--I/O status) JOBFF 21, 139, 237
182 JOBHCU 236
IOCON bit (0,,40--I/O status) JOBHRL 87, 236
15 JOBINT 122, 236
IODEND bit (0,,20000--I/O status) JOBJDA 236
14, 30 JOBOPC 238
IODERR bit (0,,200000--I/O JOBPC 236
status) 14, 30, 172 JOBRD UUO (CALLI 400050) 147
IODTER bit (0,,100000--I/O JOBREL 21, 87, 236
status) 14, 30, 172 JOBREN 238
IOIMPM bit (0,,400000--I/O jobs waiting for a device, number
status) 14, 30, 172 of 39
IONRCK bit (0,,100--I/O status) JOBSA 139, 141, 237
182 JOBTPC 115, 120, 125, 130, 238
IOP 197 JSEG bit (1000,,0--job status)
IOPAR bit (0,,1000--I/O status) 102
182 JWP bit (1,,0--job status) 102
IOSUPR bit (0,,1000--TTY I/O letters, =32 word 106
status) 163 LEYPOS UUO (PPIOT 6,) 71
IOT UUOs 5 LF insertion after CRs 41, 47
IOT-USER mode 2, 149, 233 Librascope fast band storage
IOTEND bit (0,,2000--I/O status) 133
172, 182 line characteristics 45, 48
INDEX 254

line characteristics, PTY 62 NOECHB bit (0,,400--TTY I/O
line editor Y-position 71 status) 163
line hold count 71 NOECHO bit (0,,200--TTY I/O
LINE MODE 44 status) 163
line number, finding TTY 45 non-existent memory reference
Line Printer 165 119
LINKUP UUO (CALLI 400023) 89 NXM bit (0,,10000--interrupt
LIOTM UUO (CALLI 400006) 151 bits) 119
LISTEN for connect to socket OBUFB bit (0,,100000--channel
204 status) 37
LOCK UUO (CALLI 400076) 147 OCLOSB bit (0,,1000--channel
logical device name 19 status) 38
LOGIN UUO (CALLI 15) 153 OCTAL 6
LOGOUT UUO (CALLI 17) 153 OPEN UUO (UUO 050) 20
LOOKB bit (0,,40000--channel OUT UUO (UUO 057) 31
status) 37 OUTBFB bit (0,,200--channel
LOOKUP UUO (UUO 076) 24 status) 38
LOOKUPs, long block 156 OUTBUF UUO (UUO 065) 22
lower segments SEE upper OUTCHR UUO (TTYUUO 1,) 43
segments OUTFIV UUO (TTYUUO 17,) 51
LPT 165 OUTPB bit (0,,4000--channel
LPTNCC bit (0,,100--LPT status) status) 38
166 OUTPUT UUO (UUO 067) 32
MACRO 4 OUTSTR UUO (TTYUUO 3,) 44
magnetic tapes 9, 182 overflow, arithmetic 120
mail system, inter-job 106 page printer 67, 70
mail system, inter-job, an paper tape 186, 188
example 215 parity error 118, 121
MAIL UUO (UUO 710) 106 PC flags 232
mail, receiving 108 PDP-10 information 231
mail, sending 106 PEEK UUO (CALLI 33) 105
mailboxes, peeking at 108 PGACT UUO (PGIOT 1,) 74
microswitch keyboard bits 51 PGCLR UUO (PGIOT 2,) 74
misc. UUOs 138 PGINFO UUO (PGIOT 4,) 75
modes, I/O data 8 PGIOT UUO (UUO 715) 74
monitor calls 1 PGSEL UUO (PGIOT 0,) 74
monitor commands, rescanning 48 phantom jobs 146
monitor pointers 239 physical device name 19, 40
monitor, peeking at the 100 physical name of attached
MSTIME UUO (CALLI 23) 96 terminal 54
MTAPE UUO (UUO 072) 159, 173, pieces of glass 66, 74, 75
184, 203 PIECES OF PAPER 67
MTAPE UUO for magnetic tapes PJOB UUO (CALLI 30) 98
184 plotter 186
MTAPE UUO for the disk 159 PNAME UUO (CALLI 400007) 40
MTAPE UUO for the IMP 202 POINTS UUO (UUO 712) 93
MTAPE UUO for the XGP 173 POV bit (0,,200000--interrupt
NAMEIN UUO (CALLI 400043) 100 bits) 119
network, ARPA 199 PPACT UUO (PPIOT 1,) 68
PPHLD UUO (PPIOT 7,) 71
INDEX 255

PPINFO UUO (PPIOT 5,) 70 reading data 30
PPIOT UUO (UUO 702) 68 REASSI UUO (CALLI 21) 33
PPN word of zero 17 record offset feature 157, 160
PPREL UUO (PPIOT 4,) 69 REENTER command 238
PPSEL UUO (PPIOT 0,) 68 RELEAS UUO (UUO 071) 33
PPSPY UUO (CALLI 400107) 72 REMAP UUO (CALLI 37) 89
privileges 99 RENAME UUO (UUO 055) 26, 190
project-programmer name 16, 17, RENAMEs, long block 156
98 RESCAN UUO (TTYUUO 10,) 48
protection constant of a job RESET UUO (CALLI 0) 139
236 RFCR bit (100000,,0--IMP
protection key for disk files connection status) 201
16 RFCS bit (200000,,0--IMP
pseudo-teletypes 54 connection status) 201
PTGETL UUO (PTYUUO 13,) 62 RLEVEL UUO (CALLI 400054) 100
PTIFRE UUO (PTYUUO 2,) 57 RSET bit (0,,400--IMP status)
PTJOBX UUO (PTYUUO 16,) 63 201
PTLOAD UUO (PTYUUO 15,) 62 RUN bit (400000,,0--job status)
PTOCNT UUO (PTYUUO 3,) 58 101
PTP 186 RUN UUO (CALLI 35) 142
PTR 188 RUNMSK UUO (CALLI 400046) 151
PTRD1S UUO (PTYUUO 4,) 58 RUNTIM UUO (CALLI 27) 97
PTRD1W UUO (PTYUUO 5,) 58 second segments SEE upper
PTRDS UUO (PTYUUO 10,) 60 segments
PTSETL UUO (PTYUUO 14,) 62 SEGNAM UUO (CALLI 400037) 93
PTWR1S UUO (PTYUUO 6,) 59 SEGNUM UUO (CALLI 400021) 94
PTWR1W UUO (PTYUUO 7,) 60 SEGSIZ UUO (CALLI 400022) 153
PTWRS7 UUO (PTYUUO 11,) 61 SEND UUO (MAIL 0,) 107
PTWRS9 UUO (PTYUUO 12,) 61 service level 100
PTY echoing 55 SETACT UUO (TTYUUO 15,) 50
PTY line characteristics 62 SETCRD UUO (CALLI 400073) 99
PTY line characteristics, initial SETDDT UUO (CALLI 2) 148
55 SETLIN UUO (TTYUUO 7,) 48
PTY line numbers 55 SETNAM UUO (CALLI 400002) 153
PTYGET UUO (PTYUUO 0,) 57 SETNAM UUO (CALLI 43) 98
PTYREL UUO (PTYUUO 1,) 57 SETNM2 UUO (CALLI 400036) 93
PTYs 54 SETPOV UUO (CALLI 32) 132
PTYUUO UUO (UUO 711) 56 SETPR2 UUO (CALLI 400052) 103
PTYUUOs to physical TTYs 56 SETPRO UUO (CALLI 400020) 92
PTYWAKE 46, 59 SETPRV UUO (CALLI 400066) 99
push-down stack overflow 119, SETSTS UUO (UUO 060) 36
132 SETUWP UUO (CALLI 36) 92
RAID 148, 236 SHF bit (4000,,0--job status)
random access to files 34 102
re-edited line, activation simulating UUOs 145
character of 53, 71 sixbit character codes 247
re-edited line, number of SIXBIT representation 234
characters in 49 SKPHIM UUO (MAIL 4,) 109
re-editing lines with PTLOAD 62 SKPME UUO (MAIL 3,) 109
Read-Alter (RA) mode 27 SKPSEN UUO (MAIL 5,) 107
INDEX 256

SLEEP UUO (CALLI 31) 138 TTY input buffer, peeking at 53
SLEVEL UUO (CALLI 400044) 100 TTY input buffers, clearing 49
SNEAKS UUO (CALLI 400064) 53 TTY input, LF insertion 41
SNEAKW UUO (CALLI 400063) 53 TTY line characteristics 45
sound sources 81 TTY line number, finding 45
sound system, 4-channel 192 TTY output buffer, clearing 49
spacewar buttons 111, 149 TTY UUOs, miscellaneous 52
spacewar level, executing UUOs at TTY ECHO and TTY NO ECHO 47
111 TTY FILL and TTY NO FILL 46
spacewar mode 110 TTY FULL and TTY NO FULL 47
spacewar modules, killing 113 TTY TAB and TTY NO TAB 47
SPCWAR UUO (UUO 043) 112 TTYIOS UUO (CALLI 400014) 54
SPCWGO UUO (CALLI 400003) 113 TTYMES UUO (CALLI 400047) 52
special activation mode 46, 50 TTYUUO UUO (UUO 051) 43
SPWBUT UUO (CALLI 400000) 149 TV cameras 195
SPY UUO (CALLI 42) 154 UDP 189
SRCV UUO (MAIL 2,) 108 UDSD bit (0,,100--I/O status)
SSAVE command 88 179
Stanford UUOs 5 UFBCLR UUO (CALLI 400012) 135
START command 237, 238 UFBERR UUO (CALLI 400060) 137
STATO UUO (UUO 061) 37 UFBGET UUO (CALLI 400010) 134
status word, I/O device SEE I/O UFBGIV UUO (CALLI 400011) 134
device status word UFBPHY UUO (CALLI 400055) 136
STATZ UUO (UUO 063) 36 UFBSKP UUO (CALLI 400056) 137
SWAP UUO (CALLI 400004) 140 UGETF UUO (UUO 073) 35
SWITCH UUO (CALLI 20) 102 UINBF UUO (UUO 704) 22
SWP bit (2000,,0--job status) understanding this manual 5
102 unit number of a device 40
SYSDEV bit (0,,100--channel UNLOCK UUO (CALLI 400077) 148
status) 38 UNPURE UUO (CALLI 400102) 92
system date format 95 unused opcodes 2
terminal, physical name of UOUTBF UUO (UUO 705) 22
attached 54 UPGIOT UUO (UUO 703) 72
terminals 162 UPGMVE UUO (UUO 713) 76
terminals, sending messages to UPGMVM UUO (UUO 714) 75
52 upper segments 87
terminology in this manual 5 upper segments, making and
TIMER UUO (CALLI 22) 96 killing 88
TMO bit (0,,200--IMP status) upper segments, protection keys
202 of 87, 92
TMPCOR UUO (CALLI 44) 143 upper segments, simulated 103
TPMON bit (400,,0--TTY I/O upper segments, status of 91
status) 163 upper segments, write protecting
TRPJEN UUO (CALLI 26) 153 87, 92
TRPSET UUO (CALLI 25) 153 User Disk Pack 189
TTCALL 43 user interrupt system SEE
TTREAD UUO (TTYUUO 16,) 51 interrupts, user
TTY echoing 41, 53 user level 122
TTY I/O 41 user UUOs 4
TTY I/O status word 54, 162 USET pointer 159
INDEX 257

USETI UUO (UUO 074) 35
USETO UUO (UUO 075) 35
USKIP UUO (CALLI 400041) 150
UTPCLR UUO (CALLI 13) 180
UUO mnemonics 2, 103
UUO trapping 4
UUOs 1
UUOs at spacewar level 111
UUOs by number 248
UUOs, extended 2
UUOs, obsolete 150
UUOs, simulating 145
UUOs, user-defined 4
UUOSIM UUO (CALLI 400106) 145
UWAIT UUO (CALLI 400034) 124
VDSMAP UUO (CALLI 400070) 79
video switch 78
WAIT UUO (CALLI 10) 32
WAKEME UUO (CALLI 400061) 146
word count computation 15
WRCV UUO (MAIL 1,) 108
writing data 31
XGP (Xerox Graphics Printer)
167
XGP character mode 169
XGP escapes 169
XGP video mode 167
XGPUUO UUO (CALLI 400075) 177
XPARMS UUO (CALLI 400103) 154
Y-position of line editor 71
zero PPN 18