2 Feb
2002
2 Feb
'02
2:43 a.m.
Speaking of CPU and Unibus together, there are a few
machines that follow
their own rules - the Unibus slots in a 11/730 and 11/725 (and one model
of PDP-11) are *not* wired identically to the slots in a DD11DK. Our
COMBOARD-I used certain pins for extracting the Unibus signals from the
backplane. It must be heavily modified to fit into one of these Unibuses.
The COMBOARD-II uses the "right" pins and goes into any Unibus without
modification. I don't think there are any DEC cards that have this
limitation, but I wouldn't be surprised if CBD1 wasn't the only 3rd party
card to get it wrong.
-ethan
It's been a long time -- I was trained on the 11/7xx series at DEC in
'85 or so and I don't remember any special things about their Unibus as
far as bus loads, power or signals.
IIRC they 11/730 and 11/725 were pre-cut for DMA devices and had to have
special dual-width Unibus grant cards in place if the slots were empty.
IIRC, again it was because ot the tightness of the packaging of these
slots, anything in the Unibus expansion cabinets was standard.
Bill
--
d|i|g|i|t|a|l had it THEN. Don't you wish you could still buy it now!
bpechter@shell.monmouth.com|pechter@ureach.com