From: utzoo!decvax!cca!rlb@Purdue@sri-unix
Newsgroups: net.unix-wizards
Title: Re: Alternate Troff Output Query
Article-I.D.: sri-unix.4368
Posted: Wed Nov 24 04:01:23 1982
Received: Thu Nov 25 12:19:13 1982

From: Bob Brown <rlb@Purdue>
Date: 22 Nov 1982 22:25:16-EST
For all you old-troff hackers, I'm submitting the following manual
page (we call it ptl.5, not "praise the lord").  It was written
at Purdue-CS by Eric Dittert after he was forced to repair our
versatec phototypesetter in order to complete his thesis.  Pay
particular attention to the "bugs" section.

Bob Brown
------------------------------------------------------------------
 .PU
 .TH PTL 5
 .SH NAME
ptl \- phototypesetter language; (\fItroff\fR output/\fIvcat\fR input)
 .SH DESCRIPTION
Each byte of the \fItroff\fR output file is a command to the phototypesetter.
The following is a summary of the phototypesetter instructions.
 .sp 1
 .ft B
\h'2n'Command_Byte  \h'|0.5i+15n'Meaning
 .ft R
 .RS 0.5i
 .IP "000  :" 15n
No-op.
 .IP "001-077  :" 15n
Print an ASCII character.
 .br
The character to be printed is determined by using the command_byte
(if \fIcase\fR is currently LOWER) or command_byte+64 (if \fIcase\fR is
currently UPPER) as an index into a table, the entries in which do not seem
to be ordered in any describable way.
 .IP "0100  :" 15n
Initialize.
 .br
This includes setting the modes as follows: \fIcase\fR=LOWER,
\fIhorizontal\fR=LEFT, \fIvertical\fR=DOWN, \fIfont\fR=0.
It does not change \fIpointsize\fR.
 .IP "0101-0104  :" 15n
Select font.
 .br
The phototypesetter (and hence, \fIvcat\fR) can handle four fonts,
numbered 0, 1, 2, and 3.  Consider the current font number, \fIfont\fR, as
a two-bit value.  The command 0101 resets bit 0, 0102 sets bit 0, 0103 sets
bit 1, and 0104 resets bit 1.  (And yes, we have already sent this one in to
Ripley.)
 .IP "0105  :" 15n
Set \fIcase\fR to LOWER.
 .IP "0106  :" 15n
Set \fIcase\fR to UPPER.
 .IP "0107  :" 15n
Set \fIhorizontal\fR to LEFT.
 .IP "0110  :" 15n
Set \fIhorizontal\fR to RIGHT.
 .IP "0111  :" 15n
Halt.
 .IP "0112  :" 15n
Set \fIvertical\fR to DOWN.
 .IP "0113  :" 15n
Undefined (no-op).
 .IP "0114  :" 15n
Set \fIvertical\fR to UP.
 .IP "0115  :" 15n
Formfeed.
 .br
(Added for the Versatec.)
 .IP "0116,0117  :" 15n
Undefined (no-op).
 .IP "0120-0137  :" 15n
Set point size.
 .br
The new value of \fIpointsize\fR is command_byte - 0120.
 .IP "0140-0177  :" 15n
Move vertically (lead).
 .br
The number of units to move is 0177 - command_byte.
The direction is determined by the current value of \fIvertical\fR.
 .IP "0200-0377  :" 15n
Move horizontally (escape).
 .br
The number of units to move is 0377 - command_byte.
The direction is determined by the current value of \fIhorizontal\fR.
 .RE
 .sp 1
Notes:
 .RS
 .IP 1) 0.25i
Being a single byte, each motion instruction can only specify a relatively
small number of units to move (037(oct) = 31(dec) units vertically;
0177(oct) = 127(dec) units horizontally).
Hence, it is not uncommon to see lengthy strings of similar motion commands
in \fItroff\fR output.
 .IP 2) 0.25i
The units for horizontal and vertical motion are \fItroff\fR basic units
(432 units = 1 inch).
 .IP 3) 0.25i
"Print character" instructions do not cause any horizontal or vertical
motion.
Therefore, the instructions for printing two adjacent characters are separated
by a horizontal motion command.
 .IP 3) 0.25i
There is no "new line" instruction; so, in order to avoid large numbers of
horizontal motion commands, every other line of text is reversed.
 .IP 4) 0.25i
The mode variables \fIcase\fR, \fIhorizontal\fR, \fIvertical\fR, \fIfont\fR,
and \fIpointsize\fR appear in \fIvcat\fR as \fImcase\fR, \fIback\fR,
\fIverd\fR, \fIrailmag\fR, and \fIcpsize\fR, respectively.
 .RS
 .SH SEE ALSO
pti(1), troff(1), vpr(1)
 .SH BUGS
If you are this deeply into the \fIvtroff\fR scene, you should be rewriting
\fItroff\fR for the Versatec instead of wasting time reading manual pages.