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From: glenn@gla-aux.uucp (Glenn Austin)
Newsgroups: comp.sys.mac.misc,comp.sys.mac.hardware
Subject: Re: upgrading mac SE with Gemini accelerator
Message-ID: <0E010021.d0gakk@gla-aux.uucp>
Date: 21 May 91 04:36:00 GMT
Reply-To: glenn%gla-aux.uucp@skinner.cs.uoregon.edu
Organization: The Pit Lane
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In article <6398@crystal9.UUCP>, derosa@motcid.UUCP (John DeRosa) writes:
> kentiler@matt.ksu.ksu.edu (Kent Iler) writes:
> 
> >Hi,  I was wondering if anyone has any experiance with the Gemini accelerator
> >boards fro an SE.  I was looking to boost my little SE up to 40 mhz.  Only
> >thing, I would like to have more than the 4 meg RAM that I have now, which
> >is the max for an SE.  Anyone have any suggestions?  Thanks.
> 
> The limit you will always have is 4 megs, no matter which accelerator
> that you get.  The problem is your SE ROMs, they only support 4 megs.
> 
> The only option around this is to upgrade to an SE/30.  This will
> get you a 68030 so the VM will work in system 7.0.  Also you get 
> 8 megs of hard RAM capability.   How?  New ROMs!
> 
> Of course, you will not get a 40 mhz cpu, but you can always 
> accelerate later....

This is not necessarily true -- it is possible to "move" the ROMs in the
memory map via the MMU on an '030, and there would be some necessary patching
to clean up the ROM calls within itself.  It certainly isn't impossible
to have 4GB - 256K ROM - approx 64K for I/O space = approx. 4GB memory space,
if you are using the full 32-bit address of the '030.  Therefore, it is
theoretically possible, and is being worked on, to put 16MB on an accelerator.

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| Macintosh Wizard and           |    Turn too late, much better fate."       |
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