68K (was: Happy Birthday VAX 11/780)

[Ethan Dicks]

On Sat, Oct 30, 2010 at 6:51 AM, Johnny Billquist <bqt at softjar.se> wrote:
> On 2010-10-30 01:12, Ethan Dicks<ethan.dicks at gmail.com> wrote:
>> I know it works well enough in early Sun workstations and the AT&T
>> Unix PC (3B1/7300), but I have no knowledge of any required
>> workarounds due to possible bugs.
>
> Yes, the 68010 worked fine with demand paging. The 68000 did not.
> Neither of them implemented instructions restarts, though. As noted below,
> the 68010 did instuction suspension instead.

Yes.  I was previously unaware of the distinction but did know what
the 68000 could not do that the 68010 could.

> The "interesting" workarounds that I've hear of are actually 68000-related...

> Using their own designed MMU (there were none from Motorola for the 68000),

What about the 68451?  (we had one in a prototype product design in
1984/1985 that never made it to market)

It wasn't terribly popular, but it did exist.

> and a second CPU, Apollo made the primary CPU stall on a page fault, and the
> secondady CPU wake up. The secondary CPU could then do a page in...

That sounds like the design of the Perkin-Elmer workstation I have -
two 68000s, one for running the OS, one for paging.

-ethan