Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!lll-winken!sun-barr!newstop!sun!imagen!atari!portal!cup.portal.com!Ordania-DM
From: Ordania-DM@cup.portal.com (Charles K Hughes)
Newsgroups: comp.sys.atari.8bit
Subject: Re: XL/XE RAM
Message-ID: <23199@cup.portal.com>
Date: 20 Oct 89 00:10:34 GMT
References: <47017@bbn.COM>
Organization: The Portal System (TM)
Lines: 19


  Short lesson in memory management on the XL/XE computers:

   Address  Use
 $c000-$cfff  ROM 
 $D000-$D7ff  device registers
 $D800-$FFFF  ROM

   The device registers can never be disabled, they are physically wired 
such that any instruction referencing the area from $D000-$D7FF accesses 
them.
   When you disable the ROM, you disable the entire thing and you can access
the ram from $C000-$CFFF and $D800-$FFFF.
   The best source of information for this is "Mapping the Atari" by Compute
Books.  Make sure you get the "Revised Edition" (it says that on the front 
cover).

Charles Hughes
@cup.portal.com