IBM’s secret NSA computer Harvest ran from 1962 until a worn tape-library part failed in 1976

In 1958 IBM won a contract to create a dedicated computer for the National Security Agency, resulting in the IBM 7950 Harvest, which combined the Stretch mainframe with a custom streaming processor and the IBM 7955 Tractor tape library. The architecture allowed pipelined processing of data streams and bit-level addressing, delivering a throughput of one byte every 0.3 microseconds with about 800 KB of memory. Harvest performed large-scale cryptanalytic jobs, including a four-hour search of 3.5 billion characters for 7,000 target terms and a ten-hour scan of 11 million messages against 8,000 terms.

Engineers such as Frances Allen described its capabilities as “amazing,” while NSA analysts like Robert Looney reported on its operational use. The system stayed active through the Cuban Missile Crisis, the Vietnam War, and the lead-up to the 1975 Helsinki Accords. On 27 February 1976, a worn component in the Tractor library failed, and with its supplier no longer in business the NSA could not repair the system, prompting a mock telegram to mark its retirement.