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From: jfh@killer.UUCP (John Haugh)
Newsgroups: comp.arch,comp.sys.nsc.32k,comp.sys.intel,comp.sys.m68k
Subject: Re: Question:  on-chip or off-chip MMU?
Message-ID: <814@killer.UUCP>
Date: Wed, 29-Apr-87 10:53:00 EDT
Article-I.D.: killer.814
Posted: Wed Apr 29 10:53:00 1987
Date-Received: Thu, 7-May-87 06:11:31 EDT
References: <5635@shemp.UCLA.EDU> <1774@im4u.UUCP>
Sender: usenet@killer.UUCP
Organization: The Unix(tm) Connection, Dallas, Texas
Lines: 28
Summary: Pinnacle/Logic Process used custom MMU
Xref: mnetor comp.arch:1190 comp.sys.nsc.32k:128 comp.sys.intel:224 comp.sys.m68k:451


Much has been argued in this group about whether or not Intel has a better
MMU and how slow Motorola was in getting their MMU out.

Custom MMU's are not particularly hard to build, and many companies have
done so.  Pinnacle Systems/Logic Process Co/Whoever they are next week uses
a custom MMU built out of 45ns or 35ns (depending on which machine) static
rams.  The Pinnacle XL/MPulse 10 (sounds like a merger of 2 bank cards here
in Dallas, MPact and Pulse :-) runs a 68K at 12MHz, 0 wait states, and
according to the latest rumors the Pinnacle XL020/MPulse 20 runs a 68020
at 16MHz, 1 wait state.  Supposedly John Bremsteller has been working on
getting the 020 up to 25MHz with only 1 or 2 wait states.

So, with a lack of 'on chip MMU' this little company has done about as
good as you can get.  I see no reason to argue about whether the MMU
belongs on chip or off, so long as you don't take a performance hit for
it.

And yes, when someone said an IBM-PC/?? would beat my 6MHz 68000, I too
laughed.  I have never seen a 286 running more than 4 or 5 users at 8MHz,
but I have seen 8 or 9 users on a 68000 at 6MHz, and it just gets better
with more memory, faster clock speeds, faster disks, and all of the other
new goodies that have come out in the 5 years I've had my machine.

- John.		(jfh@killer.UUCP)

Disclaimer:
	No disclaimer.  Whatcha gonna do, sue me?