NSA's Secret IBM Computer Harvest Outlived Its Usefulness

IBM secretly built a computer called Harvest for the US National Security Agency (NSA) in 1962. The machine, officially designated as the IBM 7950, was based on IBM's 7030 Stretch mainframe and was designed to process large volumes of intercepted communications without human intervention.

The NSA used Harvest for cryptanalytic and text-processing jobs, with one documented example showing the machine searching 3.5 billion characters of text in just under four hours for any of 7,000 target terms. Another job, referred to as “Moretown,” involved searching 11 million messages covering 16 years of intercepted traffic against about 8,000 search terms.

Harvest's custom processor used overlapping stages, or a pipeline, so that while one pair of data bytes was being processed, the next could already be fetched from memory. The machine had about 800 kilobytes of addressable memory and could stream one byte every 0.3 microseconds.