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@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 >
