Path: utzoo!attcan!uunet!ogicse!orstcs!usenet!jacobs.CS.ORST.EDU!parkern
From: parkern@jacobs.CS.ORST.EDU (Neil Parker)
Newsgroups: comp.sys.apple2
Subject: Re: Danger in using graphics library
Summary: Hi-res routines zero-page usage
Message-ID: <1990Nov08.111124.22108@scion.CS.ORST.EDU>
Date: 8 Nov 90 11:11:24 GMT
References: <1990Nov5.183142.31882@wpi.WPI.EDU>
Sender: @scion.CS.ORST.EDU
Reply-To: parkern@jacobs.cs.orst.edu (Neil Parker)
Organization: The Universal Society for the Prevention of Reality
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Nntp-Posting-Host: jacobs.cs.orst.edu

In article <1990Nov5.183142.31882@wpi.WPI.EDU> greyelf@wpi.WPI.EDU (Michael J Pender) writes:
>[snip]
>Does anyone know what areas of memory the hplot/hplotto/draw/
>xdraw routines use?
>
>I could just copy the areas before making 
>graphics calls, and then restore them.
>

The standard Applesoft hi-res routines use the following zero-page locations:

     $1A-$1D
     $26-$27
     $30
     $D0-$D5
     $E0-$EA (except $E3, which appears to be unused)

There seems to be a rumor floating around that the hi-res routines use
space on page 3.  This is not true--at least not for the Applesoft routines.
The original Integer BASIC graphics routines (on the Programmer's Aid No. 1
chip at $D000) did use page 3 space--they used $320-$32A instead of $E0-$EA.
They also used $50-$55 instead of $D0-$D5.  You shouldn't have to worry
about that, though, unless you expect to be running on an original
Apple ][ with the Programmer's Aid chip installed.  (We're talking ancient
history here.)

>Michael J Pender Jr  Box 1942 c/o W.P.I.   Part of this D- belongs to 
>greyelf@wpi.bitnet   100 Institute Rd.     God...  
>greyelf@wpi.wpi.edu  Worcester, Ma 01609           - B. Simpson

          - Neil Parker
--
Neil Parker                 No cute ASCII art...no cute quote...no cute
parkern@jacobs.cs.orst.edu  disclaimer...no deposit, no return...
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