General Question about UNIBUS backplanes

Noel Chiappa jnc at
Sun May 22 19:34:06 CDT 2016

    > From: Bill Degnan

    > So I decided to insert two 32K core memory backplanes

32KW, those would be MM11-U backplanes, right?

    > My plan is to replace the solid-state RAM card with core, and this will
    > free up a slot on the 4-slot backplane for a terminator.

Terminators all only go in the last slot of the last backplane anyway (either
that, or a UNIBUS 'out' cable), so adding extra backplanes shouldn't give you
"a slot .. for a terminator".

Also, Paul's point is a good one: the hex memory cards need so-called 'MUD
slots' (hex), not SPC slots (quad), and only (IIRC) the DD11-C/D have MUD
slots. (Those came in with the 11/04-34, IIRC).

    > the serial card seems to have stopped working. It appears that the
    > console program is being loaded and runs from the M9312 but nothing is
    > appearing on the terminal. I cannot send an "A" to the terminal, the
    > most basic test I can think of.

Hmm. You can read/write the console registers from the console, though, it
sounds like? My guess would be that if your serial port is EIA, somehow
you're missing -15V or something on the DD11 in its new location. Study the
-11/35-40 system manual to learn about which 'bricks' supply which voltages
to which system units.

And while you're at it, check that you have the right 'bricks' for the MM11-U.
The -11/35-40 system manual has lots of text on how to support the MM11-U.

    > Can you only use the core backplanes for core memory (assume yes), or
    > are they capable of holding other types of cards temporarily? 

AFAICR, the MM11-U backplane does _not_ have an SPC slot in it. IIRC, the
16KW MM11-U board set is a quad controller board, and 3 hex boards (core, X-Y
and something else). So two sets (the backplane holds two) would be 8, so one
empty slot - which IIRC is blank. Check the MM11-U manual, it's available.

    > I have one slot that needs the npg, it's in place.

??? _Every_ SPC/MUD slot which does not have a DMA device in it _must_ have
the jumper on the backplane (or the _double_ width UNIBUS grant card, whose
number escapes my memory, which contains a NPG jumper). Not sure if that
was the import of what you wrote there.


More information about the cctalk mailing list