Micom SRAM and DRAM Boards

I was a member of the West Coast Computer Society (WCCS) right from its first meeting in September 1976. Another member was Jack DuMoulin, who was with a local electronic consultancy company, Micom Industries Inc. Their products included two memory boards that I bought for my computer systems.

The first board I bought from Jack DuMoulin was an 8KB static RAM board for the Motorola EXORciser bus. I bought it as a bare board and assembled it. I used this with my MEK6800D1 system. I didn't keep any information on it when I sold it decades ago, and haven't found any pictures. It probably had 64 SRAM chips (2102: 1024x1 16-pin NMOS), so drew lots of power.

Five or six years later I bought a second board from Jack DuMoulin. It is a 64KB DRAM board for the SS-50 bus for my SwTPc 6809 system. I bought it as a bare board and assembled it. It draws less power and generates less heat than the two SRAM boards it replaced. It also supports extended (20-bit) addressing, although I didn't enable that feature. It uses RC controlled one-shots to generate the /RAS and /CAS signals, which isn't ideal, but I seem to remember it ran reliably in my system.

(Click on a picture for a larger version.)
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Pictures of Micom 64KB DRAM board (105-156KB .jpg).

I found two slightly different sets of documentation for this 64KB DRAM board. The first schematic is probably the modified "as built" version, since I made some modifications to the board.

Micom 64KB DRAM board schematic drawings, assembly instructions, and modification instructions.
(2.2MB PDF scanned image)

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Last revised 2020-Mar-23 11:32 PDT.
Copyright 2020 by David C. Wiens.

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