LEO (computer)

LEO I
Logo of LEO Computers Ltd 1954 until 1963
Also known asLyons Electronic Office I
ManufacturerJ. Lyons and Co.
Generation1
Release date1951; 73 years ago (1951)
CPU@ 500 kHz
Memory2K (2048) 35-bit words (i.e., 834 kilobytes) (ultrasonic delay-line memory based on tanks of mercury)
Removable storagepaper tape readers and punches, fast punched card readers and punches, and a 100 line a minute tabulator
PredecessorEDSAC
SuccessorLEO II

The LEO (Lyons Electronic Office) was a series of early computer systems created by J. Lyons and Co. The first in the series, the LEO I, was the first computer used for commercial business applications.

The prototype LEO I was modelled closely on the Cambridge EDSAC. Its construction was overseen by Oliver Standingford, Raymond Thompson and David Caminer of J. Lyons and Co. LEO I ran its first business application in 1951. In 1954 Lyons formed LEO Computers Ltd to market LEO I and its successors LEO II and LEO III to other companies. LEO Computers eventually became part of English Electric Company (EEL), (EELM), then English Electric Computers (EEC), where the same team developed the faster LEO 360 and even faster LEO 326 models. It then passed to International Computers Limited (ICL) and ultimately Fujitsu.

LEO series computers were still in use until 1981.