Small DEC QBUS backplane

Chris Zach cz at
Sun Jan 31 11:18:21 CST 2021

I only have the S (well, there is a second one in the basement I need to 
drag up). I did have one of those little 4 slot dual width boxes that 
had a power supply but I sold it. Wouldn't help with quad width modules 

There's another BA23 down there, I'll probably try to haul it up next 
trip. Was going to go over today but snow so next week most likely.

I need to sell some of this stuff. The HP1000 and the BA11-S will go on 
Ebay unless someone here wants to make an offer.


On 1/30/2021 5:20 PM, Nigel Johnson via cctalk 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.
> Can you ship to Toronto, ON?  How much?
> cheers,
> Nigel
> Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
> 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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