DEC DW11 information?

Josh Dersch derschjo at
Sat Mar 11 22:49:49 CST 2017

On 3/2/17 10:26 PM, Josh Dersch wrote:

> On 2/27/17 10:02 PM, Tony Duell via cctalk wrote:
>> >From memory it handles 18 bit addressing (not 22, of course), 
>> interrupts and
>> NPR (DMA). The Unibus side (quad card) goes in any SPC slot, you have to
>> remove the NPG jumper. It links with a pair of 40 way ribbon cables 
>> to the
>> Qbus board (dual height) which goes in the 'first' slot of a Qbus 
>> backplane,
>> where the CPU board wound normally go. AFAIK there are no real 
>> restrictions
>> on the Qbus backplane, I have used one to hang a MINC chassis off a 
>> Unibus
>> processor.
>> I seems to be transparent in operation. You just acccess Qbus devices 
>> at their
>> normal addresses.
> Cool.  I managed to snag an M8217+M9403 so all I need to do is track 
> down/build some cabling to tie the two together (any idea what the max 
> length of these cables is?).  I'm kind of hoping I can use it to run a 
> QBus SCSI controller, amongst other things. I'll report back my 
> findings...

Just to bring some closure to this thread, I had some time this evening 
to get everything hooked up:  A PDP-11/34 connected to an SB11 QBus 
chassis via a DW11-B.  And I've successfully booted XXDP and Ultrix-11 
from a CMD CQD-200 SCSI controller installed in the SB11.  Seems to work 

Thanks for the input, everyone!

- Josh

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