Xref: utzoo comp.sys.mac:32400 comp.sys.mac.programmer:6552
Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!batcomputer!mha
From: mha@batcomputer.tn.cornell.edu (Mark H. Anbinder)
Newsgroups: comp.sys.mac,comp.sys.mac.programmer
Subject: Re: System 7.0
Message-ID: <8029@batcomputer.tn.cornell.edu>
Date: 23 May 89 14:29:07 GMT
References: <3353@tank.uchicago.edu> <18660@cup.portal.com>
Reply-To: mha@tcgould.tn.cornell.edu (Mark H. Anbinder)
Distribution: usa
Organization: Department of Media Services, Cornell University, Ithaca NY
Lines: 32

In article <18660@cup.portal.com> Greg_Mark_Finnegan@cup.portal.com writes:
>Jonathan Garber's quote ("...there's only one way to do virtual memory...")
>bothers me a bit.  The Connectix VM scheme limits you to 8Meg period. Apple's
>method lets you go to 14Meg by mucking with NuBus (in 24 bit mode) and gobs
>more in 32 bit mode.
>
>Sounds like 2 ways to do virtual memory to me (and probably a judge).

I'd have to disagree with you and the judge. :-)  In 24-bit mode, Apple
is giving users up to 14 megs by allowing their virtual memory program
to access the one megabyte of addressable memory that is allotted to
each NuBus slot (NOT one meg IN each slot; it's just using the address
space), using the space that isn't being used by unused slots.

In 32-bit mode, the computer can address gobs more memory, so they let
the virtual memory program do so, if you've got the SCSI disk space!
(Lucky you, if you do! :-).

They may be using EXACTLY the same method of implementing virtual memory
as Connectix, the same way of swapping memory pages, whatever, despite 
the additional space their version will be able to access (I don't know
whether the mechanisms each company is using truly are the same).  If
the VM algorithm itself is substantially the same, THAT is what any
putative future court case would consider, NOT whether one or the other
implementation has additional features.


-- 
Mark H. Anbinder                                ** MHA@TCGould.tn.cornell.edu
NG33 MVR Hall, Media Services Dept.             ** THCY@CRNLVAX5.BITNET
Cornell University      H: (607) 257-7587 ********
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