Branching the thread away from Compaq deskpro boards: "What We Have Lost"

[Chuck Guzis]

On 8/1/21 11:45 AM, ben via cctalk wrote:

> I suspect if they had the proper virtual memory, it would have been picked
> up as a Unix cpu, instead. It is the only common non segemented 16 bit
> cpu I can think in that time frame.

There were ways around that.  You could run two, with one slightly
lagging the other, such that one would hit a trap condition before the
"real one" (was that Daisy?) Or you could limit the instruction set to
the restartable ones (Apple).

I recall attending a trade show (NCC, WESCON...?) where the Moto reps
were handing out literature (but not chips).  After a brief reading of
the 68K manual, I approached the rep with a question about implementing
virtual memory.  He looked wearily at me (he'd probably been asked the
same question a hundred times before) and quietly said, no, there wasn't
enough information saved in a trap to ensure restartability of all
instructions.

You also have to recall that at the time, virtual memory Unix was very
new--I think it was introduced with BSD in 1979 or so.  I still have a
BSD tape from Ernie (Co VAX) from that time.

--Chuck