need info on a Qbus backplane

[Jerry D]

I have several card cages that each include an eight slot, quad wide, Qbus backplane made by Dyna Five Corp and marked "PWB 201241". The plastic card guides mounted in the cages are color coded with the top three being red and the bottom four alternating white and blue. I remember that the red slots were significant but the reason has long since left my brain for parts unknown.
I'm hoping there is someone in this group who might be knowledgeable about the Dyna Five backplane specifically or, if not, at least generally knowledgeable about the Qbus backplane architecture who could provide some insight into what I have and if I'm remembering things correctly in that there's something special about the top three slots.

Any info would be most appreciated.

My apologies if this group is the wrong place for such an inquiry.

[jjh...@gmail.com]

I do not know specifics about the Dyna Five Corp backplanes. I can make some guesses which can be verified by looking at the back of the backplane and noting the traces on the circuit board. Specifically there are a number of Qbus backplane variations that have 18, and 22 bit address lines (referred to as Q18, and Q22) and the C-D interconnect (used as a private memory interconnect).

I am guessing that the Dyna Five backplane is similar to the DEC H9278 quad-8 slot backplane that has a Qbus/CD interconnect on slots 1-3, and a Qbus/Qbus connection on slots 4-8. Specifically that the red slots have the Qbus/CD slot configuration and the blue, white are Qbus/Qbus.

DEC Qbus systems, eg. 11/03, 11/23, 11/23+, micro PDP-11 and 11/73 had different Qbus backplane configurations and upgrading from a, for example 11/23 to 11/23+ required a new backplane or a mod of the existing backplane. They made it all very confusing and I don't remember all the caveats off the top of my head. I do remember that when upgrading from one system to another a lot of precautions had to be considered because some qbus cards could be destroyed, e.g. bus driver chips blown if used in the wrong configuration. If memory serves, there is a detailed explanation the the DEC micro notes (available on bit savers, along with various handbooks that describe the backplane differences).
Hope this helps. Googling 'Qbus backplanes' should turn up lots of useful information.
Good luck
J

[Johnny Billquist]

I would basically agree with the above. Seems very likely that it would
be the same as the DEC backplane that has Q-CD on the first three slots,
and then Q-Q for the rest of them.
The Qbus only occupies two backplane connectors, so for the Q-Q slots,
you usually have two Qbus cards next to each other. Quad cards will
usually have one side wired up to just pass through the Qbus signals.
However, the Q-CD slots were typically used for PMI memory (although
there might have been other cards using them for other purposes as
well). Which means they do not carry Qbus signals, and might have powers
on pins that are at odds with what a Qbus controller would expect. Some
quad cards had some jumpers in order for them to be possible to insert
in either Q-CD or Q-Q slots. Without that, yes, there is certainly a
risk of destroying something on the card if inserted into the wrong slot.

Johnny

[Richard Goodin]

So this is great... I got one of those Dyna Five Back-planes, and it has 15 Ohms between +5 and Ground. Looks like the back-plane draws about 0.3 amps with nothing in it.

Does that seem right?

[Jerry Weiss]

On Tuesday, April 4, 2023 at 9:46:27 PM UTC-5, Richard Goodin wrote:
> So this is great... I got one of those Dyna Five Back-planes, and it has 15 Ohms between +5 and Ground. Looks like the back-plane draws about 0.3 amps with nothing in it.
>
> Does that seem right?

The bus terminators if present (120 Ohm) would draw about .2 amps for a 22bit backplane. This an few led lights could use that much current.