Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!mtxinu!taniwha!paul
From: paul@taniwha.UUCP (Paul Campbell)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Why no VM on a 68K? (was: Re: Why 68000?)
Keywords: MMU virtual memory Sys. 7.0 low-end
Message-ID: <502@taniwha.UUCP>
Date: 17 Feb 90 01:15:53 GMT
References: <1990Feb11.154304.19943@smsc.sony.com> <3919@hub.UUCP> <10223@hoptoad.uucp> <1990Feb15.155556.5319@uncecs.edu> <19472@dartvax.Dartmouth.EDU>
Reply-To: paul@taniwha.UUCP (Paul Campbell)
Organization: Taniwha Systems Design, Oakland
Lines: 20

In article <19472@dartvax.Dartmouth.EDU> tga@eleazar.dartmouth.edu (Greg Ames) writes:
>And I may be going out on a limb saying this, but didn't the original
>Sun's (the 1/XX series) use a 68000 to run Unix and virtual memory?
>I was under the impression that they came out before the 68010.  If so,
>how did Sun do it?  The MMU could be implemented in custom hardware,
>but what about restarting instructions in mid-stream? (I was under
>the impression the 1/XX's used 68000's, the 2/XX's used 68010's, and
>the 3/XX's used 020's and, later, 030's).

I'm sure a 100 people will answer this but .... I think that the original
Suns got around this by having TWO 68000, the primary one never took a
bus error for a page fault .... instead it took a long 'wait state' while
the secondary one got fired up to handle the page fault .... a number
of companies used this scheme .....

	Paul
-- 
Paul Campbell    UUCP: ..!mtxinu!taniwha!paul     AppleLink: CAMPBELL.P
You know there's something wrong when 100,000 people marching in Moscow
make page 1 and 400,000 in Washington don't .....