30 Sep
2014
30 Sep
'14
5:05 p.m.
From: Antonio Carlini
> Does anyone know of a list of quad QBUS cards that
work (or do not
> work) in Q/CD backplanes
There are lots and lots of Q-bus cards so it would be
quite a long list.
Indeed; hence the "or do not work" in my original message - I realized that
that list was likely more manageable.
(Although one possible bug with the 'does not work' list is that one could get
a false positive failure...)
From: David Riley
Conversely, cards designed for the CD interconnect
(RLV11 board sets,
PMI memory, PMI CPUs) should NEVER, EVER be plugged into a Q/Q
backplane.
Off-topic somewhat, but I wonder why DEC put PMI signals, etc on power pins
(I assume that's what zaps a PMI/etc card plugged into a Q/Q slot). Surely
there are enough pins which are bus lines, etc, which one could use? Yes, the
machine probably wouldn't work if one plugged such a card into a Q/Q slot,
but you wouldn't zap boards...
> 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
-5v is an optional rail on Qbus, anyway.
Actually, I think AB2/BB2 are 'normally' -12V - although not all power
supplies provide the -12 - e.g. the BA11-N only does +5V and +12V.
In general, as long as there are removable grant
jumpers for the CD
lanes
But not all quad cards have removable grant jumpers - e.g. the BDV11 doesn't.
(Not sure why it even _has_ grant jumpers, given that one would usually make
it the last card, especially since it has pull-ups - but I guess it's in case
one doesn't.)
Noel