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From: DYOUNG@USC-ISID.ARPA (C. David Young)
Newsgroups: net.micro.atari
Subject: Re: 256K memory expansions, etc.
Message-ID: <8512092114.AA01700@ucbvax.berkeley.edu>
Date: Mon, 9-Dec-85 08:05:44 EST
Article-I.D.: ucbvax.8512092114.AA01700
Posted: Mon Dec  9 08:05:44 1985
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Chuck, Regarding your desire for someway to standardize the way extra
memory is addressed in the 8 bit ATARIs, I have come to the conclusion
that we have to accept ATARI's way of doing things, e.g. via the bank
select address at $D301. And I see why ATARI did it this way instead of
using the well established adress of $CFFF used by AXLON: they already
had $D301 decoded so that no extra logic was involved. Other than this
difference, the extra memory of AXLON and ATARI look the same (i.e. the
memory banks are mapped in the same place from $4000-$7FFF). I have even
considered adding to the AXLON ramdisk handlers built into the OMNIMON
and OMNIVIEW for the 800 the ability to convert refences to $D301 into
references to $CFFF so that programs written to run on the 130XE and
800XL's with compatible upgrades would also run on the old 800 with an
AXLON ramdisk (or its compatible). I may eventually do this, but for now
it is too far down on the priority list to think about.

As far as an extra memory 'handler' which would allow programs to
address the extra memory banks as if they were merely an extension of
the 6502 address space, the only practical solution that I can come up
with is to buy an ST.

David Young
CDY Consulting
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