MEM11 update

Ethan Dicks ethan.dicks at
Mon Feb 8 15:03:17 CST 2016

On Mon, Feb 8, 2016 at 3:30 PM, Guy Sotomayor <ggs at> wrote:
>> On 2/8/16 10:09 AM, Guy Sotomayor wrote:
>>> So, things are moving forward.  I also wanted to get folk's opinion on
>>> the need to actually produce
>>> an SPC form factor board.  In other words (and sort of in line with how
>>> peripherals were done on the
>>> original 11/20) is it OK to have the MEM11 be outside of the 11/20
>>> chassis and connect via BC11A (my replica) cables?

For my own case, I have a 3-box 11/20 that I need to restore (as I've posted
before, it was chopped apart and dumpstered, and I recovered it from there).
The majority of the second and third boxes is MM11-E core memory units
(I have N-1 because one of my co-workers nabbed a core plane to hang on
the wall).  My plan with the MEM11 has been to restore the CPU cabinet
and use the memory on the MEM11 instead of the MM11-E units, leaving
me plenty of space and power supply for peripherals with the ultimate goal
of running UNIX v1 on it (I also have an RK11C that would be a secondary
restoration project, or an RK11D that should "just work")

With that, I had been expecting that the MEM11 would be an SPC board
that would just sit in a DD11CK with some other periperhals.  Apparently,
it's sounding like there's too much "stuff" for a single quad-height card then?
Is it component density or having to go to a 4-layer board that's an issue?

> As Ian stated in a subsequent post, it'll probably be something like a 1U
> box with appropriate power supply.

That will certainly be functional, but it seems to up the cost quite a bit.

I would rather have an external something that works than not have
anything at all, but I think an SPC, if possible, would be the most
portable of solutions.

If this was an external device, would it just have a pair of 60-pin cables
to your replica BC11A?  Would it then have an onboard terminator or
option to install a terminator?  I get that you won't be selling the MEM11
as a bare board, but it doesn't seem that the intended audience would
be put out by soldering their own 60-pin connectors and/or a bunch of
terminating resistors if it needed to be at the end of a chain or in the


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