Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!mtxinu!taniwha!paul
From: paul@taniwha.UUCP (Paul Campbell)
Newsgroups: comp.sys.mac
Subject: Re: 68851 PMMU Test?
Message-ID: <384@taniwha.UUCP>
Date: 22 Jun 89 20:26:31 GMT
References: <134@nisca.ircc.ohio-state.edu> <383@taniwha.UUCP> <25656@agate.BERKELEY.EDU>
Reply-To: paul@taniwha.UUCP (Paul Campbell)
Distribution: comp.sys.mac
Organization: Taniwha Systems Design, Oakland
Lines: 25

In article <25656@agate.BERKELEY.EDU> steve@violet.berkeley.edu (Steve Goldfield) writes:
>I also installed a 68851 PMMU and a 68882 in my Mac II. I've also
>been wondering if I was successful. Are you suggesting that
>because I was able to turn the machine back on with everything
>functioning, that means both chips are properly installed?
>I'll admit I was relieved that the system seemed unaffected,
>but is it possible for something to be wrong with one or
>both of the chips without a visible problem?

I can't vouch for the '882 (just try some floating point). But in order for
a Mac II to work at all with a PMMU in it has to work with some basic
functionality (it has to be able to walk single level page tables, 
translate virtual addresses etc). The PMMU has all sorts of modes and
other crud in it, no one uses all of them, most people use a very small
subset. In the '030 MMU Mot. actually removed a lot of stuff that noone seemed
to be using in the PMMU - this has the added effect that for compatability
no one will use the stuff that got left out.

	Paul

-- 
Paul Campbell    UUCP: ..!mtxinu!taniwha!paul     AppleLink: D3213
"Free Market": n. (colloq.) a primitive fertility goddess worshipped by an
obscure cult in the late 20th C. It's chief priest 'Dow Jones' was eventually
lynched by an enraged populace during an economic downturn (early 21st C).