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From: estell@m.cs.uiuc.edu (John Estell)
Newsgroups: comp.sys.apple2
Subject: Re: Stacks, Basic, and Onerr
Message-ID: <1991Mar20.164430.14182@m.cs.uiuc.edu>
Date: 20 Mar 91 16:44:30 GMT
References: <9103191800.AA11676@apple.com> <9788@latcs1.oz.au> <1991Mar20.160105.14029@m.cs.uiuc.edu>
Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL
Lines: 29

bazyar@ernie (Jawaid Bazyar) writes:

>>"Edward M. Moore" writes:
>> I'm trying to design a program using gosubs.  One of the sections is
>> where I have a file-handeling (loading a shape table) from disk.  I would
>> like to use OnErr Goto in order to handle the error, but when that happens
>> I loose my stack of gosubs.  How can this be prevented?

>   I seem to recall there being a bug with Applesoft's error handling
>routines that could cause it to forget the gosub stack in certain cases. A
>few pokes correct the problem, but offhand I wouldn't know what they were

Adapted from the Applesoft Basic Programming Reference Manual, p. 136:

10 FOR I=768 TO 777 : READ X : POKE I, X : NEXT
20 DATA 104, 168, 104, 166, 223, 154, 72, 152, 72, 96

"Establishes a machine-language routine at location 768, which can be used
in an error-handling routine.  Clears up some ONERR GOTO problems and
?OUT OF MEMORY ERROR messages.  Use the command CALL 768 in the error-
handling routine."

Hope this helps.

------------------
 NAME: John K. Estell
 USPS: CS Dept - Univ of Illinois, 1304 W. Springfield, Urbana, IL 61801
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VOICE: "Hi John!"              QUOTE: CHR$(34)