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C00002 00002	SUPDUP.MRC[UP,DOC]
C00006 00003	 SUPDUP FEATURES:
C00010 00004	 Everything nobody wanted to know about SUPDUP's internal mappings
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SUPDUP.MRC[UP,DOC]

		SUPer-DUPer Display TELNET to ITS
			  Mark Crispin

 INTRODUCTION:

SUPDUP is the SAIL implementation of the ITS SUPDUP program, which is used
for TELNETing  between ITS  sites.   This program  uses the  internal  ITS
display codes  for highly  efficient  communication and  full use  of  ITS
display programs over the ARPAnet.  In addition, SUPDUP allows the user to
send the full  ITS ASCII  character set  (which includes  some very  hairy
characters!) and maps  both keyboard input  and display output  so that  a
Stanford display (DD, III, or DM) appears as a funny kind of ITS display.

SUPDUP will also run  on printing consoles; on  these ↑E will  controllify
the next character, and ↑↑ will enter command mode.

When SUPDUP is run,  it will prompt  for the host name.   Type one or  two
characters to identify the name  of the ITS system  you wish to TELNET  to
(ie, either  "A", "D",  "MC", and  "ML").  SUPDUP  will then  establish  a
connection  with  the  specified  ITS  site,  and  after  that  you   will
effectively be a display on ITS, with full bucky bit capability.

Some mappings in input and output are made due to the differences  between
the SAIL  and  ITS ASCII  character  sets.   Most of  these  mappings  are
transparent to the user.  The design philsophy behind the mappings was  to
cause characters typed on the Stanford keyboard  to be seen by ITS as  the
character appears on the key tops, and for characters received from ITS to
be displayed as they would be at a console at MIT.

NOTE!!!:

One thing that I should mention: you MUST NOT do a :TCTYP on ITS that will
set your terminal type.  SUPDUP's operation depends upon the terminal type
being SOFTWARE and things will not work correctly if it is set to anything
else.  It  is alright  to set  certain other  TCTYP options  such as  SAIL
character set enable, however, in general you probably will not want to do
any TCTYP  at all.   SUPDUP sets  the line  length and  page size  to  the
maximum possible on the screen.
 SUPDUP FEATURES:

  Visible OUTPUT MAPPINGS:

Caret is  mapped to  AND sign  (∧)  since there  is no  code in  the  SAIL
character set for caret.   There is no  way to tell  between AND sign  and
caret.  In addition, centered-dot, gamma,  delta, and circle-plus are  not
displayed (they generate an error message).

  Visible INPUT MAPPINGS:

αz and αZ are mapped to [CALL], αβz  and αβZ are mapped to α[CALL]; α_  is
mapped to [BACK NEXT] and  αβ_ is mapped to β[BACK  NEXT]. ↑ is mapped  to
caret; to send ↑  (distinct from VT) see  below.  Some other more  obscure
characters must be sent by using a command; see below.

  COMMANDS:

[ESCAPE]I is used to enter a  SUPDUP command.  The following commands  are
defined:

	F	Use Fast display mode (discussed below).
	K or L	Kill the job on ITS and break network connections.
	P	Temporarily restore the page printer.  Typing any
		 character will return your screen to ITS.
	Q	Quit out, close network connections, detach the job
		 on ITS if there is one.
	R	Record contents of screen onto a file; asks you for
		 name of file to write.
	S	Use Slow display mode (see below).
	V	Re-draw the current screen.
	?	Type a help text.

Command mode also allows  some of the more  esoteric ITS characters to  be
sent.  For example, ↑, α↑, β↑, αβ↑, αz, αβz, αZ, αβZ, α_, and αβ_ are sent
in image mode without being mapped.   Special mappings exist for keys  not
on the keyboard or trapped  by the monitor.  They  may be sent with  bucky
bits, and  they have  no explicit  graphic here  or on  ITS, as  they  are
special function keys.  These are:

 .	centered-dot	[TAB]	gamma		[LF]	delta
 [CR]	circle-plus	[BS]	integral	∂	[NULL]
 λ	[BACK SPACE]	≠	[CALL]		∨	[BACK NEXT]
 α	[ESCAPE]	β	[BREAK]		ε	[CLEAR]

DISPLAY MODES:

SUPDUP has two display modes; fast and slow, which are set by the F and  S
commands.  Fast mode, which is the  default, is highly optimal on  network
input  and  very  fast  on  display.   On  the  other  hand,  it  can   be
disconcerting to have  the screen  flash as suddenly  as it  does with  no
semblance  of   line-  per-line   output  (it   sort  of   comes  out   as
chunk-per-chunk), therefore, there is a  slow mode which causes SUPDUP  to
output in the old-fashioned manner which just does normal optimization but
not line/screen optimization.
 Everything nobody wanted to know about SUPDUP's internal mappings

The following character set mappings are in effect.  These mappings  occur
on both input and output,  so in general they  are invisible to the  user.
In particular, the graphic on the keytop is what ITS will see, and what is
displayed on the screen is what would be displayed on an ITS TV.  But  see
the second table and notes for exceptions.

	SAIL		ITS
	----		---

  013	 VT		 ↑	(6)

  030	 _		 ←

  032	 ~		 ≠

  033	 ≠		ALT

  136	 ↑		 ∧	(2)

  137	 ←		 _

  175	ALT		 }

  176	 }		 ~

  177	BS		INT	(1) (6)


 In addition, the following keyboard mappings are done:

	KBD code	Sent to ITS
	--- ----	---- -- ---

	   αz		   [CALL]	(3)

	   αZ		   [CALL]

	  αβz		  α[CALL]

	  αβZ		  α[CALL]

	   α_		 [BACK NEXT]	(4)

	  αβ_		α[BACK NEXT]

	    ↑		     ∧		(2) (5)

 Notes:

(1) This character  is image rubout,  which on  a PDP-11 TV  is output  as
integral sign.

(2) AND sign  (∧) is used  for caret since  there is no  code in the  SAIL
character set for caret anyway.

(3) These four mappings are necessary since there is no way that any  form
of [CALL] can be read by a user program.

(4) This mapping is necessary since there is no key remotely equivalent to
the [BACK NEXT] key.

(5) This mapping  is necessary since  otherwise there is  no way to  enter
caret from the  keyboard.  As  caret is more  important on  ITS, up  arrow
lost.  VT  will input  an up-arrow,  however it  will not  be  [TOP]ified,
meaning that in order  to enter this  character into TECO  one must use  a
quoting convention  or  up-arrow  as  a command;  see  previous  page  for
details.

(6) Output only mapping.