26 Oct
2013
26 Oct
'13
1:37 p.m.
On 25 October 2013 13:51, azd30 <azd30 at telus.net> wrote:
QQ/QQ and QQ/CD can be rewritten as AB/AB and AB/CD; or as I like to
use Q18/Q18, Q18/CD, Q22/Q22, and Q22/CD. The normal QBUS signals are
on the AB side, correct. CD has power in the same positions as on the
AB side, as well as the CD interconnect "bus." In the link to ibiblio
you have in your e-mail, the CD interconnect can best be visualized as
"all the 2 pins in one slot, go to all the one pins in the next slot."
With slot 1's 1 pins ignored, and slot n (where n is the last slot)
has all its 2 pins ignored. So yes, in effect the CD interconnect is a
private communications bus, between each separate half of the a slot,
and the half slot above and below it (so slot 1 has a private link to
slot 2, slot 2 to slot 3, 3 to 4, et cetera).
The CD interconnect is also used on the PMI capable QBUS cards, so the
11/83 and 11/93 processors (and third party replacements for those),
the PMI memories (which go *BEFORE* the processor), and the
CannotRememberItsName11 QBUS-to-UNIBUS bridge used to make the 83 and
93 into an 84 and 94. CD is also used by the QBUS VAX cards (uVAX II
for examples) in a similar private memory bus design.
As long as
quad-width cards don't mess about on the right-hand side
connectors (most of them don't) you can use any quad-width slot, whether
its wired QQ/CD or QQ/QQ.
I'm confused here. All the required signals for system operation are on the AB side
(you call it QQ?). Correct? What is on the CD side then?
I always thought that the CD side was like a 'private' communication bus, as in
the M8013 talks to the M8014. I'm not getting something here.
How would a quad card not mess about on the right hand
side? The only thing I can think of, is this. If the right hand side (CD) is wired for AB
there is power
on there. The quad card would just have to stay away from those pins. Does the CD part of
the quad card make use of the AB signals present?
By not mess around, one refers to not doing things on the CD
interconnect pins, and pulling the card into a serpentine backplane
(as that would result in card, and possibly other cards releasing the
magic smoke). I.e. the KDJ11-BF CPU I have (quad-wide 11/83 processor)
would be just fine in a Q22/CD backplane (and possibly a Q18/CD
backplane), but in a QQ/QQ backplane, that could result in damage to
the card because of the PMI interface in the CD slots.
This is based on things I remember, I'd have to reread some manuals to
give you the 100% correct information. If I remember te 1983 QBUS
Interfaces book (
http://bitsavers.trailing-edge.com/pdf/dec/qbus/EB-23144-18_QbusIntrfs_1983…
) has sections on three of the available QBUS backplanes then (H9273
Q18/CD of the BA11-N box, H9275 Q22/Q22 OEM backplane, which can fit
in a BA11-N box (I have an H92275-A but no box...), and the H9276
Q22/CD of the BA11-S box); which also has diagrams of the
interconnection of the slots in the quad width, nine long backplanes.
Cheers,
Christian
--
Christian M. Gauger-Cosgrove
STCKON08DS0