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From: mueller@hatteras.cs.unc.edu (Carl Mueller)
Newsgroups: comp.sys.amiga
Subject: Re: MAC SE has something HUMAN!
Message-ID: <16417@thorin.cs.unc.edu>
Date: 30 Sep 90 21:04:56 GMT
References: <31417@nigel.ee.udel.edu> <5950@eklektik.UUCP> <9583@uhccux.uhcc.Hawaii.Edu> <13555@wehi.dn.mu.oz>
Sender: news@thorin.cs.unc.edu
Reply-To: mueller@hatteras.cs.unc.edu (Carl Mueller)
Organization: University Of North Carolina, Chapel Hill
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In article <13555@wehi.dn.mu.oz> BAXTER_A@wehi.dn.mu.oz writes:
[... deleted stuff about the Mac SE slideshow ...]
>The story behind this is very funny. As you know, the mac roms are a pair of
>chips. Would you believe that one half of that ROM space is taken up by that
>slide show? And it's not all just on one chip. That is a real bone of 
>contention amongst mac owners who are forced to pay for a _new motherboard_
>every time they burn out a rom (which is fairly common).
>
>Regards Alan

I think you've distorted the story a bit.  The Mac SE uses the 68000,
so therefore requires 16 bits at a time from its memory chips.  Each
ROM chip supplies eight bits, so two are always required.  The Mac
Plus used 64K roms, giving a total of 128K for the system.

When the system was upgraded for the SE, they overflowed this space,
and went to the next larger size (128K roms -> 256K space).  It turns
out they didn't really need twice the space, since the system ROM
routines didn't double in size, so there was room left for the slide
show.

If my memory serves, the show consists only of two coarsely dithered
images.  Even if stored uncompressed, they would only be 22K a piece
(512*342/8).

As a sidenote, I think the latest Macs have 512K of ROM.  Anybody
found anything interesting in them?

We now return you to your regularly scheduled comp.sys.amiga :-).

-Carl Mueller (mueller@cs.unc.edu)