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From: johan@apple.UUCP
Newsgroups: net.micro
Subject: Re:  The 68010 and MMU's
Message-ID: <134@apple.UUCP>
Date: Fri, 20-Jul-84 04:56:22 EDT
Article-I.D.: apple.134
Posted: Fri Jul 20 04:56:22 1984
Date-Received: Sun, 22-Jul-84 03:21:54 EDT
References: <1999@sri-arpa.UUCP> <3@rlgvax.UUCP>
Organization: Apple Education Research Group, Cupertino CA
Lines: 18

>> 	The one thing you do need to do is always use a 68010 in ANY scheme
>> that does dynamic memory management, (to wit, most UNIX implementations), as
>> the 68000 has unrecoverable faults when a bus-error occurrs.
>
>Also not true - Masscomp uses two 68000s.  The main 68K halts on a page fault,
>and the other 68K services the page fault and restarts the main 68K.  Doing it
>with one 68000 isn't possible (to my knowledge - maybe somebody out there
>*has* squeezed blood from a stone).

The apple Lisa uses a plain 68000 and *does* squeeze blood out of the stone.
Memory is segmented and code is demand loaded. The trick is that *some*
instructions are restartable. There is much magic and kludges involved.

____________________________Computare necesse est!____________________________

	Johan Strandberg				
	Apple Computer Education Research Group [ERG]
	{mtxinu,dual,nsc,voder}!apple!johan