26 Oct
2013
26 Oct
'13
7:59 p.m.
Christian Gauger-Cosgrove wrote:
On 25 October
2013 13:51, azd30 <azd30 at telus.net> wrote:
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.
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.
However, with the uVAX II, there is also a cable over the top
connecting the CPU to the memory, so perhaps the CD portion
of the ABCD slot is not used in the same manner as with a
PDP-11/83.
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.
My one KDJ11-BF CPU is in a BA123 in the third slot with
2 DEC PMI 2 MB boards in slots 1 and 2. Slot 4 has a quad
RQD11-EC (third party MSCP controller and maybe not the
correct board number - quad ESDI controller which supports
4 EDSI hard drives).
Also, with all of this discussion of ABCD slots and PMI memory,
most, maybe all, M8190 boards also support the use of PMI
memory if placed in ABCD slots with the CPU below the memory.
They will run a bit slower than an actual KDJ11-BF with the
18 MHz crystal (as opposed to a 15 MHz crystal), but the PMI
memory provides most of the increased speed. So if anyone
has actual PMI memory (at one point maybe over 10 years ago,
PMI memory was no more expensive than regular memory maybe
due to lack of demand and understanding) and with an M8190-BB
board and a BA23, they will work well together.
Jerome Fine