NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/sys/cbm/1571

Internet Message Format | 1996-08-05 | 1.8 KB

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From: [e-mail]
Newsgroups: comp.sys.cbm
Subject: CHRGET routine on the C=64
Date: Wed, 31 Jan 1996 07:37:08 -0500
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I want to incorporate some of my own routines into BASIC.  The
C=64 Programmer Reference Guide is not much help.  This is all I
could find on it:

CHRGET routine is used by BASIC to get each character/token.
This makes it simple to add new BASIC commands....  A common way
to use this method is to specify a character (@ for example)
which will occur before any of the new commands.  The new CHRGET
routine will search for the special character.  If none if
present, control is passed to the normal BASIC CHRGET routine.
If the special character is present, the new command is
interpreted and executed by your machine language program.  This
minimizes the extra execution time added by the need to search
for additional commands.  This technique is often called a wedge.

Now, I understand this means that when you RUN a program, CHRGET
will search the BASIC RAM and look for your special symbol in
addition to all the regular commands.  Is this a correct
assumption?  My question is:   (1) How do I change the vector
from the normal CHRGET routine to point to my CHRGET routine to
search through RAM for my @ of whatever else it will be.  (2)
Where in memory do I store my CHRGET routine and the routine
after the @ to be executed.

Any help with this problem would be greatly appreciated :-)

If you could please respond by e-mail to [e-mail]
because I don't have access to a newsreader as of yet.

Thanks

Steve M.