Small DEC QBUS backplane

Nigel Johnson nw.johnson at
Sat Jan 30 16:20:33 CST 2021

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.

Can you ship to Toronto, ON?  How much?



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

On 2021-01-30 4:14 p.m., Chris Zach via cctalk wrote:
> Hm. I have a 9 slot BA11-S that I have to sell/ebay/something here,
> but that's probably way too big for you. I wonder though: Would an
> 11/93 explode if put in a traditional 18 bit 11/03 chassis? The one
> with the memory refresh lines and power for core memory.
> Probably.
> CZ
> On 1/30/2021 12:30 PM, Nigel Johnson via cctalk wrote:
>> I'm trying to repair an LSI-11/93 that has a bus timeout problem.
>> Unfortunately the BA23 box it normally sits in lives in a cupboard with
>> printers stowed on top of it and due to my domestic situation (small
>> condo) I can't get it out to scope or get a scope anywhere near it to
>> scope the bus.
>> I'm thinking that the solution would be to get a small QBUS backplane
>> that I can put on my desk in the middle of my test equipment.
>> Like a 4-slot ABAB oir even ABCD would do.
>> Does anybody have one they don't want?  Power supply not needed.
>> cheers,
>> Nigel

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