General Question about UNIBUS backplanes

william degnan billdegnan at
Mon May 23 08:38:44 CDT 2016

>     > So I decided to insert two 32K core memory backplanes
> 32KW, those would be MM11-U backplanes, right?

Here is a closeup.  I have have related docs.

>     > 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".
Thanks for clarifying.

> 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).
It is 3011-cf  / 70-12445  1979

>     > 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.
OK, but will always watch this.

> 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.

Came with M7891 RAM installed in the 3011-cf backplane.

>     > 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.

Note - System came to me as thus, after the CPU, the 3011-cf backplane had
the following:

M7856 10 F-C (RS232 WITH 19.2 OPTION?)
G7273 11 C-D
7891 12 A-F (64k MEMORY)
M9312 13 A-B (ROM CARD)
672A 13 D (GRANT CONT.)

I am going to switch to another backplane and start over.  Don't know what
I am doing yet to be honest.  I have to read the manuals and get better
educated to properly get these parts working together correctly.


@ BillDeg:
Twitter: @billdeg <>
Youtube: @billdeg <>
Unauthorized Bio <>

More information about the cctalk mailing list