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From: tim@hoptoad.uucp (Tim Maroney)
Newsgroups: net.micro.mac
Subject: Re: Rabid Defense of Multi-Tasking
Message-ID: <1051@hoptoad.uucp>
Date: Wed, 3-Sep-86 05:11:29 EDT
Article-I.D.: hoptoad.1051
Posted: Wed Sep  3 05:11:29 1986
Date-Received: Thu, 4-Sep-86 05:28:02 EDT
References: <419@sask.UUCP> <213@bridge2.UUCP>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Distribution: net
Organization: Centram Systems, Berkeley
Lines: 23

About memory management, it seems certain to me that the Open Mac will
contain an MC68851 Paged Memory Managment Unit chip.  The Programmer's
Workshop documentation contains complete support for and a number of
references to this chip, as well as the MC68881 floating-point chip.  The
thing to remember is that this is an unreleased chip, with release
tentatively scheduled for last quarter this year or first quarter next.
Motorola is not giving even tentative pricing information on it yet.  Given
this, the only way for Apple to have enough of the chips to have provided
full support in MPW for them is to have made a fairly firm agreement with
motorola to purchase a shit-load of them; and it is unlikely they would have
released documentation on communicating with the chip unless they expected
it to be of wide interest in the Mac community.

I haven't gotten an MC68851 manual yet, but I hope Motorola did better than
the MC68451 segmented memory managment unit chip.  The functionality of the
chip was great, but it took 200 ns to translate a logical address to a
physical one!  Can you say "wait states"?  I knew you could....
-- 
Tim Maroney, Electronic Village Idiot
{ihnp4,sun,well,ptsfa,lll-crg,frog}!hoptoad!tim (uucp)
hoptoad!tim@lll-crg (arpa)

These are the official opinions of the Vatican Council of Bishops.