MS11 M8110/M8120 controller card differences

Noel Chiappa jnc at
Sun May 20 13:13:28 CDT 2018

    > 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


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