22 Nov
2006
22 Nov
'06
2:48 a.m.
On 11/22/06, Chris M <chrism3667 at yahoo.com> wrote:
Yep... a 68EC030, to be specific (no MMU, thus Enforcer won't run, etc).
One _can_ replace the 'EC030 with a full 68030, but a full-on SMT
rework station is recommended.
It's easier to upgrade the CPU board to an 040 or better.
The original
A4000 was a 68020 wasn't it?
Apparently an '030. I remember reading an article that the 68010 was
more
or less a drop in replacement for the 68k in the
Ataris.
The Amiga, too. The difference is that the "MOVcc" instructions are
priv'ed on the 68010, and the stack frame can be larger, permitting
true instruction restart, and, thus, easy-to-implement page-demand
virtual memory, a-la UNIX.
One "test" for the 68010 in the Amiga is to run OS1.1 (if possible),
then fire up the calculator. You should get a Guru Meditation with a
68010 installed and not a 68000... it's an embedded MOVcc in the
application (rather than a call to the OS which _does_ know what to
to). The Calculator app that comes with OS1.2 does request the
condition codes from the OS rather than executing a potentially
illegal instruction in user mode.
My AT & T 7300 UNIX Peecee has a 68010.
Yep... it needs that for its virtual memory implementation. It's
_possible_ to design a true 68000 system with VM, but much, much
harder, typically requiring external state-saving hardware or, as in
the case of the Perkin-Elmer workstation, a second 68000 to take care
of things while the primary CPU is page faulting.
Seems the '020 is still available from Digi-Key,
but
it ain't cheap.
Anyone that still carries any of the older CPUs new is likely to have
a price that seems painful. OTOH, how many places _still_ carry the
'020? You are paying for storage and inventory, not the chip itself.
Not likely, but did anyone produce a processor
upgrade for the Lisa/MacXL?
No idea.
-ethan