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From: drw@cullvax.UUCP (Dale Worley)
Newsgroups: comp.lang.forth
Subject: Debugging Aids for Forth
Message-ID: <1456@cullvax.UUCP>
Date: Wed, 12-Aug-87 11:04:46 EDT
Article-I.D.: cullvax.1456
Posted: Wed Aug 12 11:04:46 1987
Date-Received: Fri, 14-Aug-87 06:07:04 EDT
Organization: Cullinet Software, Westwood, MA, USA
Lines: 21

I once implemented FIG-Forth on the PDP-11 (translating from their
6502 or whatever distributed (paper!) version, and put in simple
debugging facilities.  These included breakpointing and
single-stepping (the tricky part is stepping over a complex
colon-word).  Breakpointing isn't too hard, you just have a BREAKPOINT
word that you write over the breakpointed colon-word reference, just
as in assembler debugging.  Single stepping is harder, because you
have to modify the NEXT (?) routine to watch to see if it's supposed
to interrupt after executing the colon-word.

Anyway, once you've hit a breakpoint, you go back to the standard
input-eval loop, which lets you screw around with things and then
resume execution.

I might still have the code floating around, if anyone's interested.

Dale
-- 
Dale Worley	Cullinet Software		ARPA: cullvax!drw@eddie.mit.edu
UUCP: ...!seismo!harvard!mit-eddie!cullvax!drw
OS/2: Yesterday's software tomorrow	    Nuclear war?  There goes my career!