25 Oct
2012
25 Oct
'12
7:16 p.m.
On Oct 25, 2012, at 10:02 PM, Dave McGuire wrote:
On 10/25/2012 09:14 PM, Jon Elson wrote:
I was gonna say. The PMI interconnect for QBUS doesn't supply enough
address pins for VAX-sized memory, nor is it 32-bit, so MV boards have
their own ribbon cables as a side channel. Not knowing much about VAX
failure modes but having plenty of experiences with touchy ribbon
cables, I'd say that might be a good first bet.
- Dave
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.)
Actually the MicroVAX-II uses a PMI interconnect on a daisy-chained
ribbon cable across the tops of the memory and CPU boards, in addition
to the C-D interconnect.