25 Oct
2012
25 Oct
'12
6:48 p.m.
At 09:14 PM 10/25/2012, Jon Elson wrote:
Memory is NOT on the Q-bus, it has it's own
dedicated bus on
the C-D connector rows (how many slots are memory only in the
CD rows depends on the specific backplane.) Possibly you
might have a Q-bus board in a memory-only slot, that is certainly
something to check. Otherwise, you may have a bad memory card,
a bad or dirty slot, or possibly a bad CPU board.
Ah yes, you're right. Microvax 2, so memory's not on the Q-bus. It's
got to be a bad memory area. Enabling windows or AUTOGEN has just moved
that bad chip to somewhere that's now being used.
Hmm, I've never seen this error, but I think if a
peripheral
board is bad, it does not cause a machine check, but maybe I've
never had the specific error. Can you tell what the physical
address was? or, at this point, might virtual=physical?
If so, is 7FF3xxxx in the Q-bus I/O space?
No, it's a virtual address. You're running with memory management
enabled by that point, so the only way to figure out what physical
address this corresponds to is to look at the page tables, which you
could get from running SDA on the resulting dump.
At this point, it's pretty likely to be a memory fault. Unless you're
going to try to find out what chip to replace, my suggestion to remove
RAM until it stops failing so the bad board can be isolated is probably
the best simple diagnostic.
Eventually, running diagnostics is probably the best thing to try. It's
probably bad RAM but could also be a bad CPU. However, my experience
with bad CPU modules is that they don't get very far along the boot
process before dying.
-Rick