>    But wait...why would this have anything to do with Qbus (and its 22bit
> address space) at all?  Wouldn't such other-processors-accessing-my-memory
> transactions happen over the PMI bus?

in the KA630 (and KA65* series), the PMMI can only have one processor.
so a multiprocessor KA630 would be several CPU's each with their own
PMMI and its own RAM boards.  moving data from a CPU to some other CPU's
memory would go over the QBUS, using a very UNIBUS-map kind of mapping
scheme.  this is not very different from how the 782 worked.  if you
wanted direct access to all memory then the total memory in the system
would have to be 4MB or less.  far better to do specific page sharing
for DMA-like access, and let your total memory be the total of all that's
addressable by all PMMI's.  as der mouse said, this isn't traditional SMP
but it's not completely antithetical to traditional SMP either.