Harvest: The Most Interesting Computer You Never Heard Of

Peter Capek covers Harvest, a unique IBM 7950 developed for the NSA to handle codebreaking and text work. Harvest was an add-on to IBM's Stretch (7030) and operated on the same memory. The talk places it in the context of early transistorized machines, when computing was batch-oriented and data storage relied mostly on tape.

The middle of the talk covers the design. Harvest treated memory as one long string of bits and used two streaming units to pull variable-width bytes from memory, pass them to table lookup and logic units, and write results back. Match units could trigger actions at roughly thirty points in the machine. The tape subsystem, called Tractor, was an unusually fast cassette library, and the talk describes Alpha, the specialized programming notation used to drive the hardware.

The closing section covers the machine's history. It ran from 1962 to 1976, when mechanical wear on the tape system ended its service, and IBM later bought it back after a congressional push for public bids. The takeaway is how much engineering and funding went into custom cryptanalytic hardware, and how many of its ideas, such as standardized I/O and byte-oriented addressing, shaped later IBM designs.