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From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.mac
Subject: Re: Is 68020 + 68851 == 68030
Message-ID: <8297@cbmvax.UUCP>
Date: 26 Oct 89 19:27:31 GMT
References: <1178@lzsc.ATT.COM>
Organization: Commodore Technology, West Chester, PA
Lines: 17

in article <1178@lzsc.ATT.COM>, mkg@lzsc.ATT.COM (Marsh Gosnell) says:

> Is there any difference (other than a wait state) between a 68020 and
> the MMU and a 68030?  This question came up at a user group meeting and
> I'd like to get the answer.

They're practically the same, software-wise.  There are some 68851 instructions
and addressing modes that aren't supported by the 68030 (these can be emulated,
but it's better to use the 68030 subset, and most folks do), and the 68030 has
two transparent translation registers that aren't supported by the 68851.  The
big change in MMUs comes with the 68040....

>   Marsh Gosnell  mkg@lzma.att.com
-- 
Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests"
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