> On Jan 30, 2022, at 2:43 PM, Chris Zach via cctalk <cctalk@classiccmp.org>
> wrote:
>
> ...
> From what I can see, the the kmc11 was an M8204 single board which is
> different from the 8200 used in the dmc11. I had a DMC11 somewhere.
>
> From the books, the kmc11 had an "lsi11 on board", 1k of 16 bit ram, 1k of 8
> bit data memory a 300ns cycle time, 16 bit microprossor with a 16 bit
> micro-instruction bus and 8 bit data path. This is according to the 1980
> Terminal and Communications handbook, so it's a few years after the 1976
> timeframe of Sha Tin.
A KMC-11 has no resemblance whatsoever to an LSI-11 or any other PDP-11
processor. It's a custom microcontroller designed to be a coprocessor on the
Unibus.
The DMC-11 processor card is not quite the same thing as a KMC-11; its firmware
is in ROM rather than RAM, for one thing. I don't know if there are any subtle
instruction set differences. Certainly the architecture is at least mostly the
same; this can be seen from the fact that RSTS at startup probes various
internal state of the DMC-11 by making it execute instructions, and those
instructions can be readily understood by reading the KMC-11 manual.
It looks like the DMC-11 had a 1k program ROM, the KMC-11/B a 4k RAM, and the
DMR/DMP microprocessor seems to be 6k ROM (the drawings are a bit confusing).
A consequence of the tiny program memory in the DMC was that the high speed
version had a couple of limitations and bugs, described in the DMC-11
microprocessor manual.
paul
