DEC DW11 information?

Tony Duell ard.p850ug1 at
Tue Feb 28 00:02:32 CST 2017

On Tue, Feb 28, 2017 at 4:32 AM, Josh Dersch <derschjo at> wrote:
> Hi all -
> Anyone have any technical information (manuals, schematics, etc.) for the
> DEC DW11 UNIBUS->QBus interface?  I'm curious to know what it's capable of

I am pretty sure I have the printset for it somewhere. I think the
VS11 prints also
include it (the VS11 is a VSV11 with said interface to allow it to be
used on the

> and what the requirements are, especially on the QBus side of things.  What
> kind of backplane is required?  I assume it doesn't support 22-bit QBus
> devices given the age of the interface (and the complexity required to do
> so), but does it handle 18-bit devices, or only 16?

>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

I seems to be transparent in operation. You just acccess Qbus devices at their
normal addresses.


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