Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!mips!apple!dlyons
From: dlyons@Apple.COM (David A. Lyons)
Newsgroups: comp.sys.apple
Subject: Re: Basic memory crash...
Message-ID: <38614@apple.Apple.COM>
Date: 13 Feb 90 23:09:51 GMT
References: <8228@wpi.wpi.edu>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 23

In article <8228@wpi.wpi.edu> greyelf@wpi.wpi.edu (Michael J Pender) writes:
>[...]
>My other thought is that since I request pages for the screen image
>data, but don't mark these pages used in the bitmap (since they're 
>only temporary) that they might be being overwritten by BASIC
>or something.

Marking pages used in the $BF-page bitmap is not necessary--it only
tells ProDOS not to read/write that memory; it won't affect how BASIC.SYSTEM
uses the memory.

Calling GETBUFR (BASIC.SYSTEM) will not give you pages that are being
used for Applesoft storage, although it will move existing Applesoft
strings down to make room.
-- 

 --David A. Lyons, Apple Computer, Inc.      |   DAL Systems
   Apple II Developer Technical Support      |   P.O. Box 875
   America Online: Dave Lyons                |   Cupertino, CA 95015-0875
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   My opinions are my own, not Apple's.