Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!tut.cis.ohio-state.edu!ucbvax!MIAMIU.BITNET!RC1DSANU
From: RC1DSANU@MIAMIU.BITNET (Ryan Collins)
Newsgroups: comp.sys.atari.8bit
Subject: Re: 64K
Message-ID: <8908272245.AA07246@ucbvax.Berkeley.EDU>
Date: 27 Aug 89 23:31:34 GMT
References: <SINCLAIR_R@WUMS>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
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  In reply to the msg about upgrading an Atari 800 to a full 64K, It can't be d
one without a major reworking of the computer. The Atari, being an 8-Bit
computer, can only access 64K of memory at one time. In the XL's and XE's
with 64K, only 48K is easily accessible at one time. To access the other 16K
that is "under the OS", mapped in the memory where the OS is, you must use
location $D301 of the PIA. Its 8 bits are used to turn internal Basic on/off,
turn OS on/off, turn Diagnostic Rom on/off,or select extra RAM (above 64K) if
there. The Atari 800 has this location of the PIA controlling joysticks 3&4.
To change it would require the newer OS out an XL be put in the 800, and
something would have to be done with internal Basic and the diagnostic ROM.
It would be so mush easier to buy an XL or XE. (Analog Mag has an ad for an
Atari 1200XL for $50.00!!!)

                         Ryan Collins
                       a.k.a Gozar
Ataris rule forever!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!