I believe that DM11 was designed by Vince Bastiani, (SP) after the
DM11 he designed the UART - that is another story - with one or more
vendors.
The backplane - as I recall - was dedicated to the DM11 Comms interface.
here is the board list
M7240 DM11 U DM11-A control
M7241 DM11 U DM11-B control, quad
M7242 DM11 U DM11-C control
M7243 DM11 U DM11 transmitter D
M7244 DM11 U DM11 transmitter E
M7245 DM11 U DM11 receiver, quad
M7246 DM11-BB U Modem control scan, 16 lines, DM11-BB
M7247 DM11-BB U Modem control MUX, 8 lines
On Wed, Oct 2, 2019 at 10:33 AM Noel Chiappa via cctalk
<cctalk at classiccmp.org> wrote:
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.
Noel