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C00002 00002			SUPer-DUPer Display TELNET to ITS
C00005 00003	SUPDUP FEATURES:
C00009 00004	Everything nobody wanted to know about SUPDUP's internal mappings
C00012 ENDMK
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		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.

     When SUPDUP is run, it  will prompt for the  host name.  Type one  or
two characters to identify the  name of the system  you wish to TELNET  to
(ie, either "A", "D", "MC", "ML",  or "S").  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],
and α_  is mapped  to  [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.  REENTER does this too.
	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, and α_ 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)

	    ↑		     ∧		(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.