Reverse engineering circuitry in a Spacelab computer from 1980

# Summary Spacelab, a reusable laboratory carried by the Space Shuttle, was controlled by the Mitra 125 MS, a French-built minicomputer that lacked a microprocessor and instead had its 16-bit processor constructed from multiple circuit boards. The computer used TTL (transistor-transistor logic) chips rather than modern microprocessors, with the 74181 ALU chip being one of its most complex components containing approximately 170 transistors.