🚀 go-pugleaf

in article <13822@well.UUCP>, nagle@well.UUCP (John Nagle) says:

> In article <822@rodan.acs.syr.edu> jstewart@rodan.acs.syr.edu (Ace Stewart [Jonathan III]) writes:
>       The MC68030 has a built-in MMU comparable to (but not
> compatible with) the PMMU.  So all '030-based machines are in theory
> capable of running a virtual memory operating system with protected
> memory.

Actually, the 68030 Internal PMMU is very similar to the external 68851 PMMU
that can be used with the 68020 in machines like the Mac II.  There are a few
additional addressing modes for some instructions in the '851, there's no
support for CALLM/RTM in the '030's MMU (or the '030 for that matter), and the
'030 adds two "transparent translation" registers, which support simple mapping
of I/O regions in a virtual system.  The 68851 also has a larger Address
Translation Cache (64 vs. 22 entries).

So, while there are slight differences, it's quite simple to write code that
works on both MMUs just fine.

If you're looking for a major change in MMU architecture, the 68040 will be
along someday soon...

>       					John Nagle

-- 
Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests"
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