On Aug 7, 2025, at 5:59 PM, Chris Hanson via cctalk
<cctalk(a)classiccmp.org> wrote:
On Aug 7, 2025, at 2:44 PM, Mike Stein <mhs.stein(a)gmail.com> wrote:
AFAIK the 68000 and 68010 were also available in a pin-compatible package, as in the
Cromemco XPU.
Yeah, the 68010 was essentially a "minor" revision of the 68000, and shared the
same pinout in all packages.
It was really a "more than minor, less than major" revison: The 68010 did
change exception stack frame layout and added a register and a couple supervisor-only
instructions to meet Popek & Goldberg virtualization requirements, added the
two-instruction loop cache, and added a signal that indicates a read-modify-write cycle is
taking plce for multi-processor support (which was only actually brought out to a pin on
the 68012, like the additional 7 address lines).
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.
paul