In 1979, Honeywell Information Systems announced a new programming language for their time-sharing service named TEX, an acronym for the Text Executive text processing system. TEX was a first-generation scripting language developed around the time of AWK and used by Honeywell initially as an in-house system test automation tool.

TEX extended the Honeywell Time-Sharing service (TSS) line editor with programmable capabilities, which allowed the user greater latitude in developing ease-of-use editing extensions as well as writing scripts to automate many other time-sharing tasks formerly done by more complex TSS FORTRAN programs.

Overview

TEX was a subsystem of Honeywell Timesharing (TSS). Users would enter the TSS command tex to change to a TEX session mode of operation. TEX expressions could be entered directly on the command line or run from a script file via the TEX command call ⟨filename⟩.

TEX programs are a collection of TSS line editing commands, TSS session commands, and TEX statements. TEX variables could be inserted into TSS commands, and TSS line editor commands via the TEX variable substitution feature. TEX programs were primarily designed to extend the line editor system. Consequently, TEX had no concept of file input/output relying instead on applying line edit commands to the working file and saving as needed.

The key developers of TEX at Honeywell were Eric Clamons and Richard Keys with Robert Bemer, famous as the father of ASCII and grandfather of COBOL, acting in an advisory capacity.^[1]

TEX should not be confused with TeX a typesetting markup language invented by Donald Knuth.

The American Mathematical Society has also claimed a trademark for TeX, which was rejected because at the time this was tried (the early 1980s), "TEX" (all caps) was registered by Honeywell for the "Text EXecutive" text processing system.^[2]

TEX Variables

All variables ^[3] were stored as strings and converted to integer numeric values when required. Floating point variables, arrays, or other datatypes common in current scripting languages did not exist in a TEX environment.

All variables were stored in a single global variable pool which users had to manage in order to avoid variable naming conflicts. There were no variable scoping capabilities in TEX. Variable names were limited to 40 characters.

TEX provided several internal read-only registers called star functions^[4] which changed state when certain TEX string parsing operations were executed. Star functions provided a means to get the current date and time, resultant strings from a split or scan string parsing operation or from TEX internal call level and TSS session information.

The maximum length of a string value was 240 ASCII characters. This includes intermediate results when evaluating a TEX expression. Numeric string values are limited to 62 digits in the string, including the (-) for negative numbers. Numeric values are also normalized where leading zeros are stripped from the string representation.

Some examples of variable usage:

   _ we can use quotes or other characters as delimiters as long as the string doesn't contain them
   _ and can use the comma operator to concat them together
   _
   a="hello"
   b=/world/
   c=a,/ /,b

   _ the out statement prints "hello world" to the terminal without quotes
   _
   out:c

   _ Using TEX variables in a line editing command to find a line containing "hello"
   _ replacing the "hello" string with the "hello world" string
   _
   rs:a:c

TEX Operators

TEX has three types of operators:^[5]

• arithmetic
• boolean
• string

When constructing a TEX expression, all spaces must be compressed out except for string literals. In general, spaces delimit TEX statements.

    _ NOTE: In the "d=" statement, there are no spaces between the commas 
    _ or the variables
    a="hello"   b=" "   c="world"   d=a,b,c   out:d

    _ In contrast, a space  is needed to separate the 'if' from its expression and 
    _ the expression from the next TEX command to conditionally execute
    _
    if a:eqs:"hello" out:a

   a=1
   b=-2
   c=3*(a-b)/(2*2+(4+1))

   if name:eqs:"luke"   out:"May the force be with you!"

   if ^age:gtn:500  out:"Heh, you can't be Yoda!" 

   _ an example of an and construct
   if a:eqs:'a'   if b:eqs:'b'  goto !its_true
   goto !its_false

   _ an example of an or construct
   if a:eqs:'a'   goto !its_true
   if b:eqs:'b'   goto !its_true
   if c:eqs:'c'   goto !its_true
   goto !its_false

   !its_true out:"It's true!" goto !next_block
   !its_false out:"It's false!" goto !next_block

   !next_block
   ...do something...

   a="hello"," "," world"

   a="hello world"
   b=a']5
   c=a]'5

   out:"It's a strange new ",c," but ",b," anyways!"

   a="hello world"
   b=a'>" "

   out:b

TEX Labels

All TEX statement labels were prefixed with a (!).^[11] Statement labels were ignored unless referenced by a goto^[12] or call^[13] statement. One notable feature of TEX was the ability to call or goto labels in other files. Coupled with the TEX SUBS mode meant that TEX could create new scripts via line editing, save, and then call or goto labels in these scripts dynamically.

The mypgm.tex file:

   !hello
   out:"hello world"
   return

   !hello2
   out:"hello world again"
   exit

   (end-of-file marker)

Calling by label example:

   call /mycat/mypgm.tex!hello

In the above example, TEX would process the /mycat/mypgm.tex file searching for the !hello label(*). TEX would continue processing the file until a return statement or exit statement was executed, or an end-of-file was reached.

Goto by label example:

   goto /mycat/mypgm.tex!hello2

In the next example, TEX would process the /mycat/mypgm.tex file searching for the !hello2 label(*). TEX would continue processing until an exit statement or end of file was reached. An error would be thrown if a return statement was executed and there were no CALLs active.

(*) TEX did not check for duplicate labels in the same file, consequently execution was unpredictable if present.

TEX Substitutions

TEX provides the SUBS and NOSUBS commands to activate or deactivate variable substitution for TEX statements or TSS commands.

   xx=/out:"Hello World"/

   subs ?

   ?xx?
      
   nosubs

   ?xx?

In the above example, the xx variable contains a TEX output statement as its value. The subs command specifies that (?) is the substitution character for all future statements of the program. Upon processing the first ?xx? line, TEX will substitute the out:"Hello World" command for ?xx? and then execute the resultant statement. The nosubs command turns off substitutions for subsequent statements and so TEX issues an error when it tries to execute the second ?xx? line.

TEX Indirections

In addition to variable substitution, TEX supported variable indirection. Variables prefixed with the underscore character (_) were considered to contain a variable name as their contents and so TEX would use indirection to get the value. TEX limited indirection to 64 levels to avoid possible looping.

As an example:

   a="b"
   b="c"
   c="hello world"

   _ here the out:__a would print "hello world" to the terminal, 
   _ since two underscore prefix of a means a >> b >> c
   out:__a

TEX Input/Output

Honeywell Timesharing sessions had a concept of the working file. To edit an existing file, you would first make it the working file via the old command. To create a new file, you would first create it via the new command. Once changes were complete, you would either save (for new files) or resave the working file. Basically only one file could be open for editing at a time.

TEX programs were primarily designed to extend the line editor system. Consequently, TEX had no concept of file input/output relying instead on making changes to the working file via line edit commands and saving as needed.

However, TEX did provide terminal-oriented input/output commands:

• in -- print a prompt and pause until text is entered, storing it in the *in star variable
• out -- print a message

A simple example using in and out:

   in:"What is your name?"

   out:"Hi ",*in

TEX Star Functions

as a means to access results/side-effects of TEX subsystem functions or to represent ASCII terminal codes.^[14]

A list of star variables follows:

• *account - user account number associated with the current userid
• *cl - the current line of the current file being edited
• *lcl - the length of the *cl value
• *clvl - current depth of calls
• *date - current date in the form of YY-MM-DD
• *eof - T if positioned after the last line of the current file or when there is no current file
• *in - contains the last response to an in or int TEX command execution
• *lin - length of *in
• *left or *l - left string from scan or split command execution
• *lleft or *ll - length of *left
• *middle or *m - middle string from scan or split command execution
• *lmiddle or *lm - length of *middle
• *right or *r - right string from scan or split command execution
• *lright or *lr - length of *right
• *null - represents the null string
• *random - contains a randomly selected digit from 0 to 9
• *rmdr - remainder of the last division operation
• *snumb - system number of the last batch job run
• *svmd - TEX commands to restore the TEX modes at the time of the last interfile call or goto
• *sw00 to *sw35 - examines the TSS 36-bit switch word with 1 bit returning a T value and a 0 bit returning a F
• *time - current time in hh:mm:ss always to the nearest second
• *userid - current userid

Commands

TEX was built on top of the TSS line editor, as such line editor commands could be used within a TEX program. TEX programs may have:

• TSS line editing commands
• TEX commands
• TEX mode changing statements
• TSS subsystem commands

   verb:<search_expr>;<repeat_cnt>;<occurrence_cnt>:<replacement_string>

   !ELIM_DUPS a=*cl f;1
   _
   !NEXT_LINE if *eof out:"task complete" return

   b=*cl if a:eqs:b d;1 goto !NEXT_LINE

   a=b f;1 goto !NEXT_LINE

TEX Examples

This code was excerpted from a TEX based Adventure game written by a team of Explorer Scouts from GE Post 635, Schenectady New York circa 1980. The Adventure game was the first of several popular online text-based adventure games available on the GE Timesharing service. The scouts decided to create their own adventure game using TEX. The original Adventure game used two word commands to navigate Colossal Cave. The parser shown below handled simple two word commands like go west or move right and converted them into x,y deltas for positioning and directional orientation in the game.

Parsing the Adventure two word commands:

   ...

   _ force a clear screen on the televideo terminal
   !init 
   out:*esc,":"
   
   _ clear program variables
   rmdr=*null
   del=0
   dir="n"
   xlocn=1    ylocn=1
   return

   _ _______________________________________________________________
   _
   _ The PARSER subroutine interprets your input commands and tries to 
   _ pre-process them prior to returning to your program.
   _
   !parser
   qry=*cr,*lf,"-->" sntc=*null call !ask1
   ergo !unkn_cmd verb=ans vdel=0 goto !$ans$_cmd
   _
   !walk_cmd   del=2     call !move_to  return
   !run_cmd    del=4     call !move_to  return
   !fly_cmd    del=6     call !move_to  return
   !swim_cmd   del=2     call !move_to  return
   ...
   !unkn_cmd   return

   !move_to call !ask3 if ans:eqs:*null goto !to_$dir$
   ercall !to_same call !to_$ans$
   _
   !to_locn xlocn=xlocn+xdel ylocn=ylocn+ydel return
   _
   !to_f
   !to_forward
   !to_ahead
   !to_same goto !to_$dir$
   _
   !to_b
   !to_backward goto !inv_$dir$
   _
   !to_r
   !to_right goto !rt_$dir$
   _
   !to_l
   !to_left goto !lt_$dir$
   _
   !inv_south
   !rt_northwest
   !lt_northeast
   !to_n
   !to_north dir="north" xdel=0 ydel=del return
   _
   !inv_west
   !rt_northeast
   !lt_southeast
   !to_e
   !to_east dir="east" xdel=del ydel=0 return
   _
   !inv_north
   !rt_southeast
   !lt_southwest
   !to_s
   !to_south dir="south" xdel=0 ydel=-del return
   _
   !inv_east
   !rt_southwest
   !lt_northwest
   !to_w
   !to_west dir="west" xdel=-del ydel=0 return

   _ adjust delta speed if these words are spotted as in "go very fast"
   !to_very vdel=vdel+1 goto !to_same
   !to_fast del=del+vdel vdel=0 goto !to_same
   !to_slow del=del-vdel vdel=0 goto !to_same

   _ ______________________________________________________________
   _
   _ The ASK subroutines get your terminal input and break it up depending
   _ on the spaces. ask1 falls into ask2 and ask2 falls into ask3 then returns
   _
   _ rmdr holds remainder of input line, sntc holds remainder of current command sentence
   _ sentences are terminated with a period. ans holds the current word being processed
   _
   !ask1 if rmdr:eqs:*null in:qry rmdr=*in sntc=*null
   !ask2 if sntc:eqs:*null scan:rmdr:"." sntc=*l rmdr=*r]'1
   !ask3 scan:sntc:" " ans=*l sntc=*r return

Rolling dice:

   _ _______________________________________________________________
   _
   _ The DICE subroutine rolls the dice for you and returns the answer
   _ in the variable called DICE.
   _
   _ Input to the DICE subroutine is via the DICE variable as shown below :
   _
   _     1d6 - roll the 6-sided die once
   _     3d8 - roll the 8-sided die 3 times
   _     d%  - roll the 100-sided die once (percentage roll)
   _
   !dice if dice:eqs:"d%" dice="1d100"
   scan:dice:"d" i=*l j=*r dice=0
   
   !dice_1 
   k=*random if j:gt:9 k=k,*random
   k=k/j dice=dice+*rmdr+1
   i=i-1 if i:gt:0 goto !dice_1
   
   clear i clear j clear k 
   return

Televideo screen codes:

   _ _______________________________________________________________
   _
   _ The following routines allow you to easily draw pictures on the
   _ the Televideo 950 terminal.
   _
   _      xyplot: positions the cursor
   _ 
   _      gr:     turns graphics mode on
   _
   _      nogr:   turns graphics mode off
   _
   _      clear:  clears the screen
   _
   _      load:   used by xyplot to load the xytbl
   _
   !xyplot
   ercall !load xytbl=xytbl
   cx=(xytbl]'(x-1))']1
   cy=(xytbl]'(y-1))']1
   out:*ESC,"=",cy,cx,z
   return
   _
   _
   !load
   xytbl=" !",/"/,"#$%&'()*+,-./"
   xytbl=xytbl,"0123456789:;<=>?",*AT,"ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_"
   xytbl=xytbl,"`abcdefghijklmnopqrstuvwxyz{|}~",*DEL
   return
   _
   _
   !gr nosubs
   out:*ESC,"$" subs $
   $*SVMD$ return
   _
   _
   !nogr out:*ESC,"%" return
   _
   _
   !clear out:*ESC,":" return

Notable TEX Features

The most notable feature in TEX was its SUBS mode allowing variable values to crossover and become executable code. It allowed a programmer to create new variables on the fly to be used in later TEX expressions in a LISP-like fashion. TEX also allowed programmers to create scripts on the fly via line editing, saving the content to file later to be executed as part of the current program using interfile call and goto statements. However, in most cases, these features were used to provide simple dynamic goto statements in code as seen in the Adventure game parser example. What other kinds of Artificial Intelligence constructs could be developed were never fully explored.

An example of creating variables on the fly and then using them to do an interfile goto.

   _ incorporate x,y,z into the global variable pool
   cmd="x=1 y=2 z=3"
   subs ?
   ?cmd?

   _ next we modify mycat/mypgm_1_2.tex to say "hello world" we are writing some code to 
   _execute later in our script
   _
   old mycat/mypgm_1_2.tex
   r:*cl:/!label_3 out:'Hello World'/
   resave mycat/mypgm_1_2.tex

   _ lastly we subs in x,y,z and then evaluate the goto mypgm_1_2!label_3 which does an interfile goto
   _
   goto mycat/mypgm_?x?_?y?.tex!label_?z?

The TEX program above illustrates dynamic script creation and then execution via substitution, file editing and interfile goto. In effect, programs writing programs were possible although never done. In the above example, the mycat/mypgm_1_2.tex file would be executed at label_3 printing out "hello world".

References