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From: ForthNet@willett.pgh.pa.us (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: nephyte needs f83 examples & examples
Message-ID: <2845.UUL1.3#5129@willett.pgh.pa.us>
Date: 4 Jun 91 02:40:54 GMT
Organization: (n.) to be organized.  But that's not important right now.
Lines: 56

Category 1,  Topic 33
Message 40        Sun Jun 02, 1991
F.SERGEANT [Frank]           at 23:07 CDT
 
     Maybe I shouldn't butt in regarding your Atari & F83 questions,  Paul,
but I will anyway.  I don't have an Atari so I'll assume you have  a version
of F83 that is almost identical to the IBM PC version and  make my suggestions
accordingly.

     What you should do to start with is _read_ the documentation that  comes
with F83.  It should tell you how to approach becoming familiar  with F83. 
Most of its documentation is not in the form of text files,  manuals, etc., so
it should be a simple matter to read what _is_ in  such form.  Then follow its
suggestions regarding VIEWing words.  Use  VIEW on a likely prospect (such as
OPEN or CREATE-FILE) to get you into  the general area of the source code. 
Then read the source code and the  shadow screens that go with it.  Don't just
read the one screen that  VIEW throws you into: also read the surrounding
screens (using N and B  or whatever the editor commands are that move forward
one screen or  back one screen; A should switch between source and shadow
screens).  Make note of other words used within the definitions of the word
you  are VIEWing so you can VIEW those words also.  A way to get likely 
candidates to VIEW is to type WORDS and see the words in the  vocabulary. 
Beware that some of the words you need to research may  reside in a different
vocabulary (such as DOS or HIDDEN or ???) so you  may need to change
vocabularies and do WORDS several times.  Eventually  you will be able to find
the exact word to create a new file, _and_ its  stack comment (so you'll know
how to use the word).  This is one of the  beauties of a system that comes
with complete source code.

     Your method of copying an existing file to a new name and erasing  all
its text and then using the file for your own purpose is also a  perfectly
workable method for making a new file.

     Now, _why_ didn't that Starting Forth example you typed in work?   Again,
you should research it.  To do this you should study the example  to
understand what it is doing and how it goes about it.  Then try  typing in the
example word by word (you can't type in the looping,  branching, >R R@ R> type
words), checking the stack after each one,  perhaps DUMPing memory or checking
the values of VARIABLEs, in order to  actually see what is happening.  (By
typing in the example, I mean to  execute the parts of each definition, one by
one, from the keyboard.)  Another possibility is to use F83's trace or debug
facility, but I  might recommend you delay that until you've tried the method
I just  suggested.  By using this system you will locate an F83 word that 
doesn't do what you expected it to from the Starting Forth example.  Then use
VIEW and study its source and shadow code until you understand  the difference
and can adjust for it.

     If you follow these suggestions, please post a follow up letting  us know
how it all works out.

  -- Frank
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