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IBM 701 — The Speed Demon

IBM's first commercially available scientific computer was the 701, the first of the IBM 700 series. Developed in a record two years, it was introduced to the public in 1953. Earlier named the Defense Calculator, it was mainly funded by the Pentagon — the impetus came from the Korean War and the need for equipment capable of operating at higher speed and accuracy. Despite the name, the Defense Calculator was a stored-program computer.

The initial nomenclature referred to the 701 as "machines" since it comprised 11 connected units. Later usage adopted the singular form.

Taming the Speed Demon

The 701 could perform more than 16,000 addition or subtraction operations per second, read 12,500 digits per second from tape, print 180 letters or numbers per second, and output 400 digits per second from punched cards. At that point IBM was facing a problem — how to keep the machine busy. This led to hardware and software being considered the yin and yang of computing.

The bottleneck was programming. Only a small number of people had the knowledge. Programs would be written on paper, punched onto cards, and fed into a card reading machine. Any bugs required the whole procedure to be repeated. It was time for a "better way" of programming. And that better way was FORTRAN.