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From: dsmall@well.sf.ca.us (David Small)
Newsgroups: comp.sys.atari.st
Subject: Re: how about an upgrade to 68010
Message-ID: <22795@well.sf.ca.us>
Date: 21 Jan 91 23:54:57 GMT
References: <A1444681262@thelake.mn.org> <22662@well.sf.ca.us> <1991Jan17.203526.15849@math.lsa.umich.edu>
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 35


Howard's question concerns installing the 68010 CPU into an Atari.

	First, the 68010 is the same sized chip as the 68000. Thus it plugs
in. That's the only easy part.

	You'll need to build an adaptor board with 256K-size ROM sockets (2)
on it, mapped with an address decoder to $e0 0000. (I've gotten in the habit
of splitting up big hex numbers that way). You'll then need to get TOS 1.6 or
1.62 (I have not worked with 1.62), find every hardware access to the STE
stuff, and NOP it out. You'll have to burn that into EPROMS and somehow
connect the adaptor board to the Atari; we did it through the Mega slot.

	TOS 1.6 just won't fit in the old TOS ROM sockets. Two reasons: It's
64K too big, and it is relocated from the original $fc 0000 TOS address to the
new $e0 0000 TOS address, so the first hard coded jump would crash.

	THEN, you need to make sure that $e0 001a (if I remember right) is
presented to the bus on RESET so the CPU knows where to power up to. I think
you can do that by connecting a pin of the old TOS ROM socket that would
select
at RESET to the address decoder, but you're getting out of where I feel 
comfortable.

	After all this, you'll experience an extremely mild speed increase,
and have a little bit of all that's needed for VM and MMU mapping available;
the 68010 required external chips to do it, which you'd have to wire on.

	My personal feeling is the project is worthwhile only if it would be
fun to do for the learning experience and challenge. It took us some time to
pull it off.

	Also, Quick-Index doesn't run on the 68010. Tisk, tisk, tisk.

	-- thanks, Dave / Gadgets