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IBM Installs its First Stored Program Electronic Computer, the 701, but They Don't Call it a Computer

Photograph of IBM 701 Electronic analytical control unit.

IBM 701 Electronic analytical control unit.

"The 701 has at least 25 times the over-all speed but is less than one-quarter the size of IBM's Selective Sequence Electronic Calculator, which was dismantled to make room for its speedier successor."

"During its five-year reign as one of the world's best-known "electronic brains," the SSEC solved a wide variety of scientific and engineering problems, some involving many millions of sequential calculations. Such other projects as computing the positions of the moon for several hundred years and plotting the courses of the five outer planets -- with resulting corrections in astronomical tables which had been considered standard for many years -- won such popular acclaim for the SSEC that it stimulated the imaginations of pseudo-scientific fiction writers and served as an authentic setting for such motion pictures as "Walk East on Beacon," a spy-thriller with an FBI background.

"Though the 701 occupies the same quarters as the SSEC, which it rendered obsolete, it is not "built in" to the room as was its predecessor. Instead, it is smartly housed between serrated walls of soft-finished aluminum. A balconied conference room, overlooking the calculator and, separated from it by sloping plate glass, provides a vantage point for observing operations and discussing computations. Ample space is provided for writing the complex and abstract equations that are the stock in trade of engineers and scientists in an age of atomic energy and supersonic flight.

"The 701 uses all three of the most advanced electronic storage, or "memory" devices -- cathode ray tubes, magnetic drums and magnetic tapes. The computing unit uses small versions of the familiar electronic tubes, which are able to count at millions of pulses a second. In addition, several thousand germanium diodes are used in place of vacuum tubes, with resultant savings in space and power requirements.

"The 701 was designed for scientific and research purposes, and similar components are adaptable to the requirements of accounting and record-keeping. Research on commercial, data processing machines is under way.

"The 701 is capable of performing more than 16,000 addition or subtraction operations a second, and more than 2,000 multiplication or division operations a second. In solving a typical problem, the 701 performs an average of 14,000 mathematical operations a second."

(quotations from IBM's original May 27, 1953 press release from the IBM Archives website).

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