Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!ux1.cso.uiuc.edu!uxa.cso.uiuc.edu!jb10320
From: jb10320@uxa.cso.uiuc.edu (Jawaid Bazyar)
Newsgroups: comp.sys.apple2
Subject: Re: Apple IIGS's Memory Limit
Message-ID: <1991Jun21.090808.7620@ux1.cso.uiuc.edu>
Date: 21 Jun 91 09:08:08 GMT
References: <1991Jun20.221622.561@crash.cts.com>
Sender: usenet@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at Urbana
Lines: 30

rhood@pro-gsplus.cts.com (Robert Hood) writes:

>In-Reply-To: message from MQUINN@UTCVM.BITNET

>Re: Theoretical memory limit on the GS - 8 MB?  16 MB?  17.125 MB?
> 
>I'm shocked.  In all of this thread I've seen, everyone has mentioned only
>what is directly accessible.  Has everyone forgotten the 128K 8-bits?  The
>address space on a 6502/65C02 is only 64K - surely someone could figure out
>a way to do something similar with the GS, no?

   ICKY!  NASTY!  FOO!  The whole point of having a processor that can
directly access 16 megabytes is so you don't have to use bank switching.
Adding bank switching would be a fruitless task on the GS.  A much better
project would be true demand paged virtual memory. 
   According to the hardware reference, cards that follow Apple's design
rules for memory cards can have to 4 megabytes, period.  Add this 4 meg
to whatever the machine you've got has on the motherboard (ROM 01- 256k,
ROM 03- 1.125Meg), and that's the total in your machine.  I doubt a card
like the Octo RAM would work in a ROM 03, but I think AE's GSRAM+ does,
so there you have 6Meg+1.125Meg for close to eight.
   It might be possible to build a 12Meg RAM card, but it would be useless
because the Memory manager is only built for 8 megs.


--
Jawaid Bazyar               |  "Twenty seven faces- with their eyes turned to
Graduated!/Comp Engineering |    the sky. I have got a camera, and an airtight
bazyar@cs.uiuc.edu          |     alibi.."
   Apple II Forever!        |  I need a job... Be privileged to pay me! :-)