MITS Boards

This came from a box of old computer equipment. It's two boards joined together by stand-offs and several wires. Only one of the boards has a bus connector edge.

Update from a reader:

It's a S-100 board, intended for the MITS Altair 8800. The bottom board with the edge connector is a MITS serial board. The "TTL" designator indicates that it does not shift the serial data to RS-232 levels. The mezzanine board on top is an early modem board.

The large IC (COM2502) is a standard 40-pin UART. Look up the Western Digital TR1602 for pinout and function. Quite a number of manufacturers made their own 40-pin UARTs that, while having different pin names and sometimes different speed capabilities, were almost always pin-compatible.

This is the "top" view. Click the image for a larger version.

The outward side of one board is labeled "Modem 80".

The other board is a "Serial TTL" that was apparently used with a cassette recorder to load and save programs.

This is the largest IC on the serial board.

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Updated May 5, 2012