DEC QBUS Backplanes

[Pete Turnbull]

On 17/04/2020 17:52, Bill Gunshannon via cctalk wrote:
> 
> I found a backplane.  It says
> Digital on it but does not  have an H- number.  I also
> don;t find it listed in any  of the lists I can find on
> the web.
> 
> It has 8 A-B slots and 4 C-D slots.  the Four C-D are on
> the bottom half of the backplane.  I am assuming it is
> 18 bit and the C-D were intended for things like the 2
> board RL controller.

Is it quad height or hex height?  Is there a picture anywhere?
It sounds a bit like an H9278-A, which is a 22-bit 4 x 8 (ie quad 
height, 8 rows) backplane for a BA23 box.  That has a mixture of Q22 and 
CD in part and Q22 on the rest, but the rows with CD are the top rows.

http://www.dunnington.info/public/PDP-11/QBus_chassis

-- 
Pete
Pete Turnbull