Processor Technology 3P+S I/O Board S-100 Vintage 1976 Altair IMSAI Sol-20

Untested sold as is

Up for sale is an original Processor Technology 3P+S Input/Output board, manufactured in 1976 (copyright date silkscreened on the PCB: “Processor Technology Corp. C1976”). Board reads “3P+S, I/O Rev a” with a serial number field on the board.

The 3P+S was one of the most widely used I/O boards in the early S-100 bus/Altair 8800 era, supplying three parallel ports and one RS-232C serial port. It let a single card handle a teletype and up to two TV typewriter/keyboard setups simultaneously, and Processor Technology later paired it with their VDM-1 video board to help create the Sol-20, one of the first all-in-one personal computers. A key piece of early microcomputer history — compatible with Altair 8800, IMSAI 8080, and other S-100 bus systems.

• Board shows visible period-correct tantalum capacitors and hand-soldered jumper wires (see photos