RE: [N8VEM-S100:253] An interesting implementation of MC68000 demand paging...

["Andrew Lynch" <lyn...@yahoo.com>]

Hi!  The next version of the S-100 68K CPU board is going to come out soon.
My plan is to order some prototype boards in the near future and probably
this upcoming weekend.

There is a lot of activity lately and I have to space out my prototyping and
PCB buying due to cost.  However the next S-100 68K CPU board is probably
going to be here in less than three weeks.

So far, I am thinking Pontus and Mike are on the build and test team for
sure.

Thanks and have a nice day!

Andrew Lynch

> -----Original Message-----
> From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On
> Behalf Of mike
> Sent: Friday, June 03, 2011 10:12 AM
> To: n8vem...@googlegroups.com
> Subject: [N8VEM-S100:253] An interesting implementation of MC68000 demand
> paging...
> 
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> 
> Hi All,
> 
> I was just browsing through some of the m68k source in the uClinux
> kernel and started researching the Apollo series after looking at some
> of the support code that looked kind of interesting.
> 
> The early models where based on the MC68000 processor and did, in fact,
> implement demand paging. How they did it was very cleaver. They actually
> ran two 68K processors, one was the main processor and one was a sort of
> MMU assitant such that when the MMU hardware detected that a page would
> fault, it would force the main 68K processor into wait-state while the
> second processor handled the fault and swapped in the page or whatever
> it needed to do.
> 
> I though this was extreemly cleaver, and goes back to something Andrew
> was saying about the 68K MMU that I've been working on that if we could
> keep it sort of generic, it might be able to be used on other processors
> on the S100 bus. Well, using an approach similar to this might make
> demand paging possible with some of the processor that otherwise would
> not be able to support demand paging.
> 
> Anyway just thought I'd share that very interesting tidbit.
> 
> Kind Regards,
> 
> Mike Sharkey
> 
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