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EDSAC

A stored-program computer built at Cambridge by Maurice Wilkes that ran its first programs on 6 May 1949.

Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory built EDSAC. Work began in 1947. It ran its first programs on 6 May 1949, calculating a table of square numbers and a list of prime numbers.

It used mercury delay lines for memory and vacuum tubes for logic. The delay lines held 512 words in each of two batteries. The firm J. Lyons and Company used its design to build the LEO I. EDSAC shut down on 11 July 1958.

Why it matters

EDSAC gave a regular computing service to researchers at Cambridge. Lyons used its design to build a commercially applied computer, the LEO I.

Key facts

  • Work began in 1947.
  • First programs ran on 6 May 1949.
  • Used mercury delay lines for memory.
  • Led to Lyons' LEO I.
  • Shut down on 11 July 1958.

Sources

  1. Wikipedia, "EDSAC", en.wikipedia.org/wiki/EDSAC, accessed October 14, 2026.
  2. Wikipedia, "Maurice Wilkes", en.wikipedia.org/wiki/Maurice_Wilkes, background reading, accessed October 14, 2026.