Editing LEO (computer) (section)

{{Short description|1951 British computer}}
{{Use dmy dates|date=August 2020}}
{{Infobox information appliance
| name         = LEO I
| aka          = Lyons Electronic Office I
| logo         = Leo badge 4.JPG
| logo caption = Logo of LEO Computers Ltd 1954 until 1963
| image        =
| caption      =
| developer    =
| manufacturer = [[J. Lyons and Co.]]
| type         =
| generation   = 1
| release date = {{Start date and age|1951}}
| os           =
| CPUspeed     = 500&nbsp;kHz
| memory       = 2K (2048) 35-bit words (i.e., 8{{frac|3|4}} [[kilobyte]]s)
| RAMtype      = ultrasonic [[delay-line memory]] based on tanks of [[mercury (element)|mercury]]
| memory card  = [[punched tape|paper tape]] readers and punches, fast punched [[Punched card input/output|card readers]] and punches, and a 100 line a minute tabulator
| predecessor  = [[EDSAC]]
| successor    = LEO 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 [[University of Cambridge|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&nbsp;I and its successors LEO&nbsp;II and LEO&nbsp;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&nbsp;360 and even faster LEO&nbsp;326 models. It then passed to [[International Computers Limited]] (ICL) and ultimately [[Fujitsu]].

LEO series computers were still in use until 1981.