Need DM11 documentation

Noel Chiappa jnc at
Wed Oct 2 09:33:26 CDT 2019

Hi, does anyone out there have any DM11 documentation? The only thing I could
find online is the "DM11-BB model control option manual" (DEC-11-HDMBA-A-D) -
and it's the impetus for this request, actually.

One page 1-5, pg. 15 of the PDF, it has a diagram of which boards go into
which slots on the DM11 backplane - and ir has _two_ boards marked M7245! So
something's clearly wrong.

The DM11 is a fascinating oddball of an interface, BTW. (It's in the 1972
edition of the "peripherals and interfacing handbook".) A lot of its internal
state is kept in main memory, and accessed via DMA! This includes the incoming
data shift registers!!! So it can really chew up a bus - probably why it was
dropped ASAP. I guess when it was done, memory in chips must have been expensive
and/or not very dense; and it must have been before the first UART chips.


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