30 Sep
2014
30 Sep
'14
10:27 a.m.
Does anyone know of a list of quad QBUS cards that work (or do not work) in
Q/CD backplanes (other than the board pairs specifically designed to go in a
Q/CD backplane, of course)? I tried Google, but either there is no such list,
or my Google-fu is pretty weak.
For instance, I'm looking at a BDV11, and it has the usual grant jumpers on
CM2-CN2 and CR2-CS2, but I don't think those will be a problem (provided there
is no quad board immediately next to it). Similarly, CB2 is tied to DB2, and
the two feed (through a jumper which is normally removed) special power (-5V)
for a particular kind of EPROM; but again, I don't think this will be a
problem (again, if blank neighbour slot).
But I'd rather not have to go through that exercise for every quad card; it
would be nice if there's a table which just says which ones are OK. (I did
find mention, in the 1980 Interfaces Handbook, in the BA11-N entry, that
MMV11-A modules will _not_ work in a Q/CD backplane, which _implies_ that
all the rest are OK, but...)
Noel
30 Sep
30 Sep
10:50 a.m.
On 30/09/14 18:27, Noel Chiappa wrote:
Does anyone know of a list of quad QBUS cards that
work (or do not work) in
Q/CD backplanes (other than the board pairs specifically designed to go in a
Q/CD backplane, of course)? I tried Google, but either there is no such list,
or my Google-fu is pretty weak.
This explains the situation quite clearly:
http://hoffmanlabs.org/openvms/hwvax/hwqbus.shtml
I don't know of a specific list. There are lots and lots of Q-bus cards
so it would be quite a long
list. I think you might have to work it out for yourself on a
card-by-card basis.
Antonio
11:22 a.m.
On Sep 30, 2014, at 1:27 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
Does anyone know of a list of quad QBUS cards that
work (or do not work) in
Q/CD backplanes (other than the board pairs specifically designed to go in a
Q/CD backplane, of course)? I tried Google, but either there is no such list,
or my Google-fu is pretty weak.
The SHORT (but by no means definitive) answer is that most boards designed
to work in a Q/Q (generally serpentine) backplane will work fine in a Q/CD
backplane; they generally just use the power pins on the CD connectors and
have optional jumpers. As you pointed out, there are exceptions, but in my
experience, they're relatively rare and you'll probably see lots of warning
about them when you look up the card.
Conversely, cards designed for the CD interconnect (RLV11 board sets, PMI
memory, PMI CPUs) should NEVER, EVER be plugged into a Q/Q backplane.
That's a good way to let out the magic smoke.
For instance, I'm looking at a BDV11, and it has
the usual grant jumpers on
CM2-CN2 and CR2-CS2, but I don't think those will be a problem (provided there
is no quad board immediately next to it). Similarly, CB2 is tied to DB2, and
the two feed (through a jumper which is normally removed) special power (-5V)
for a particular kind of EPROM; but again, I don't think this will be a
problem (again, if blank neighbour slot).
-5v is an optional rail on Qbus, anyway.
But I'd rather not have to go through that
exercise for every quad card; it
would be nice if there's a table which just says which ones are OK. (I did
find mention, in the 1980 Interfaces Handbook, in the BA11-N entry, that
MMV11-A modules will _not_ work in a Q/CD backplane, which _implies_ that
all the rest are OK, but...)
That's a REALLY weird module; there were very few /11s from the Qbus era
that used core. It probably won't work because it needs core voltages
(+20v, -5v if I recall correctly from the recent Unibus discussion) that
are only present on special backplanes to begin with.
In general, as long as there are removable grant jumpers for the CD
lanes, you should be good putting most quad boards in Q/CD backplanes.
Just be careful about the reverse situation.
- Dave
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a.carlini＠ntlworld.com -
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jnc＠mercury.lcs.mit.edu