7 Aug
2025
7 Aug
'25
5:51 p.m.
On Aug 7, 2025, at 5:43 PM, Paul Koning <paulkoning(a)comcast.net> wrote:
A very important enhancement in the 68010 is that you could take a page fault and handle
it in a way that allowed virtual memory systems. Apollo Computer built some of the first
workstation products, with VM, using a pair of 68000s running in lockstep, to make page
faults work with a chip that didn't handle it right.
That’s why I said:
> The 68010 did change exception stack frame layout
and added a register and a couple supervisor-only instructions to meet Popek &
Goldberg virtualization requirements
All instructions need to be restartable to meet the Popek & Goldberg requirements,
whether they trap due to a privilege violation or a bus error. Memory is just one of the
things that can be virtualized once a system meeds the requirements.
-- Chris