MS11 M8110/M8120 controller card differences

Bob Smith bobsmithofd at
Mon May 21 11:24:52 CDT 2018

11/35 vs 40, I think there was some attempt to discriminate between
the two, as the /35 with no added boxes was a great little machine
cost and performance wise, I recall the timing being different when
going through the prints for the two machines, got parts for 35 out of
surplux, checked the backplane and there was one wire different, fixed
it toe match /40 and we gave away the machine as a retirement gift to
one of the guys who was starting somekind of boat shop in Maine, can
remember his face. maybe his name but that was a long long time ago!!

On Sun, May 20, 2018 at 2:13 PM, Noel Chiappa via cctalk
<cctalk at> wrote:
>     > From: Bob Smith
>     > 8110 for MOS memory, and 8120 for bipolar memory is what field guyde
>     > list says.
> Well, the early bipolar MS11-C (1K boards) used the M8110 during early
> production (see e.g. DEC-11-HMSAA-D-D, pg. 1-1), and apparently then switched
> over to the M8120. I've only seen the later MS11-A bipolar (4K boards - dunno
> why it's in reverse alpha order) associated with the M8120.
>     > I think the there was some change from special select parts and a move
>     > to schottky 74S series around the time of the 45/50 days.
> I wondered that, but the MS11-C and MS11-A are the same speed (300 nsec);
> although maybe the M8110 was a bit marginal, and component changes in the
> M8120 made it more robust?
> I guess I'll have to do it the hard way, and compare the ICs... :-(
>     > 11/40 was faster than 11/35, but if you changed a wire, they were the
>     > same.
> I've heard of other manufacturers doing that, but I thought the /35 and /40
> were identical, except for the number on the console inlay, and the sales
> channel?
>         Noel

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