Small DEC QBUS backplane

Nigel Johnson nw.johnson at
Sat Jan 30 17:58:09 CST 2021

OK, thanks, Glen, i didn't think of that! Not sure why they would do
that with all memeory on-board!

One thing I though of was just buying some IDC 36-pin card edge
connectors and wiring them together for the work bench!



Amateur Radio, the origin of the open-source concept!
Skype:  TILBURY2591 nw.johnson at

On 2021-01-30 6:08 p.m., Glen Slick via cctalk wrote:
> On Sat, Jan 30, 2021 at 2:20 PM Nigel Johnson via cctalk
> <cctalk at> wrote:
>> Yes the BA11S would be too big. Can't see why not for the 11/03 chassis.
>> I used to make a good living upgrading 1/03 chasses with four extra bits
>> for the 11/23/73  (Hmm, where is my old stock of W933 bus strip!)
>> Always works except in the MINC laboratory system, which used those four
>> pins for module identification.
>> Since all the memory is on-board with the 11/93 I don't think it would
>> make a difference unless DMA used, and I don't plan to go that far!  I
>> could always wire-wrap them.
> The KDJ11-E 11/93 has PMI signals on the CD connectors, so you need a
> Q/CD backplane, such as the 18-bit 4x9 H9273, the 22-bit 4x9 H9276, or
> the 22-bit 4x8 H9278 (BA23 backplane).
> The 4x4 H9270 is a Q/Q backplane, so that would cause a conflict with
> the PMI signals on the CD connectors of the KDJ11-E 11/93.

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