Remote job submission from PDP-11

Dave Mitton dave at
Thu Oct 8 14:11:32 CDT 2020

>Date: Wed, 7 Oct 2020 11:29:43 -0700
>From: Glen Slick <glen.slick at>
>Subject: Re: Remote job submission from PDP-11
>On Wed, Oct 7, 2020 at 11:04 AM Paul Koning <paulkoning at> wrote:
> >
> > > On Oct 7, 2020, at 12:06 PM, Glen Slick via cctalk 
> <cctalk at> wrote:
> > >
> > > ...
> > > I was curious about this DEC M8704 DMS11-DA that sold cheap a few days
> > > ago. It has eight SMC COM5025 "Multi-Protocol Universal Synchronous
> > > Receiver/Transmitter USYNR/T" chips:
> > >
> > >
> > >
> > > Apparently it can't do anything on its own. It needs to be connected
> > > to a UNIBUS through a companion KMC11 processor board, which might not
> > > be too common if someone wanted to put together a working
> > > configuration.
> >
> > That model number isn't familiar.
> >
> > A KMC-11 is simply a microprocessor that sits on the Unibus and 
> does Unibus cycles to another device on behalf of the host.  The 
> idea is to offload operations so the host can ask for block 
> transfers and the KMC does the individual character I/O operations needed.
> >
> > That said, it clearly is not correct that "it can't do anything 
> on its own".  The KMC-11 reaches into the device via its Unibus 
> CSRs.  If you can find a description of its operation, or reverse 
> engineer it, you can clearly write a device driver for it that 
> doesn't rely on a KMC-11.
> >
> >         paul
>Well it does appear that M8704 DMS11-DA "can't do anything on its own"
>directly through the UNIBUS. From a quick visual inspection it only
>has power and grant continuity traces on the card edge connectors. The
>connection to the controlling KMC-11 is through the 40-pin Berg
>connector. So without a KMC-11 an alternate interface through the
>40-pin Berg connector would be needed.

My first job at DEC was to release the KMC-11 Programmer's Tools 
support for RSX-11.
(I didn't write them from scratch, two other engineers did that, but 
I did do final debug and QA)

We provided two firmware kit products; the CommIOP-DUP and DZ, which 
controlled the DUP-11 and DZ-11 respectively.

The KMC-11 could do NPR bus transfers to/from the devices, and the 
CommIOP-DUP firmware could do Bisync or X.25 type framing so that you 
got an RSX-11 driver with a packet interface, vs byte at a 
time.   The CommIO-DZ firmware provided various customizable state 
driven things as you might want for a line driven terminal 
concentrator.  I'm pretty sure the packages came with the "source" 
code, so you could customize it if you could understand it.

The DMC-11 did DDMCP support and was basically a KMC with ROM in the 
control store.  And it did use that external connector to the 
proprietary network interface card, DMC-11DA.

In later years, I wrote and released a KMC Tools package for 
VMS-11.  That came with a VMS DMA LP-11 line printer driver I authored.
I don't remember if the CommIOP tools were supported.  Some VMS 
engineers didn't like these products. (another story)
(That didn't stop the Lab products guys in Marlboro from using them 
for their applications)

There was a later version called the KMC-11B which doubled the memory 
and probably ran faster too.  It was the same board as the DMP-11 
product which was an improved version of the DMC-11.

These were quad Unibus boards.  In the Q bus world, there was a 6502 
based I/O processor card developed (outside of Networks) (as one-chip 
micros became available) as well.

I have a KMC-11 Programmer's Manual here... I think you'll need a 
print set to figure out that connector.


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