HP-71 PLEX & LEXCAT

[KimH]

One more step forward, thanks for the explanation!

(11-04-2020 04:11 PM)Joe Horn Wrote:  LEXCAT requires the PEEKUTIL lexfile. Although it outputs a lot of useful information about lexfiles and their commands, it only outputs information which is easily looked up inside the lexfile, such as the number and type of function arguments. However, command options (which are not in parentheses after the command, e.g. "EXTEND" in OPTION EXTEND) are not as easily discerned and therefore LEXCAT makes no attempt to figure them out.

What follows is my writeup about it from The Titan File, published in HPX Exchange, V1 N3, May/Jun 1987.

RUN LEXCAT (or CALL LEXCAT(F$) with a filename in F$), and see the hex address of the specified lexfile, the address of its poll handler(s), the address of the next file, and all the keywords in the lexfile with their execution code address (entry point), lex ID and token number, and function syntax. This is an invaluable program for those of us who use lexfiles a lot. It is based on a program by HP, with a few more bells and whistles, cleaner output, and much faster thanks to PEEKUTIL.

If LEXCAT is run on SPLEX, you’ll see (with varying addresses):
*** SPLEX ***
(80008) File Header
(80077) Poll Handler
(800D5) 52/24 LIST$(#,?$)
(80281) 52/23 MODIFY
(808C4) Poll Handler
(80900) 53/55 MAXRC fn
(809F1) Next File Header

which means SPLEX’s file header begins at hex address 80008; its first poll handler begins execution at hex 80077; the LIST$ function starts execution at hex address 800D5, it has lex ID 52 (hex), token 24 (hex), and takes one numeric argument, followed by an optional string argument; the MODIFY keyword is a statement (no clue to its syntax!); there’s another poll handler at 808C4; MAXRC is a function with no arguments; and the file ends at 809F0.