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
