Editing LEO (computer) (section)

== Applications and successors ==
[[File:LEO III computer circuit board 2012.JPG|thumb|upright|A circuit board from a LEO III computer]]

Lyons used LEO I initially for valuation jobs, but its role was extended to include [[payroll]], [[inventory]], and so on. One of its early tasks was the elaboration of daily orders, which were phoned in every afternoon by the shops and used to calculate the overnight production requirements, assembly instructions, delivery schedules, invoices, costings, and management reports. This was the first instance of an integrated management information system.<ref>{{cite web |last1=Frank |first1=Land |title=The story of LEO – the World's First Business Computer |url=https://warwick.ac.uk/services/library/mrc/explorefurther/digital/leo/story/ |website=Warwick University - Modern records centre |access-date=7 August 2018}}</ref> The LEO project was also a pioneer in [[outsourcing]]: in 1956, Lyons started doing the payroll calculations for Ford UK and others on the LEO I machine.  The success of this led to the company dedicating one of its LEO II machines to bureau services.  Later, the system was used for scientific computations as well. [[Met Office]] staff used a LEO I before the Met Office bought its own computer, a [[Ferranti Mercury]], in 1959.<ref>{{cite web |url=http://www.metoffice.gov.uk/corporate/pressoffice/anniversary/computers.html |title=History of computing at the Met Office |work=Met Office website |access-date=2010-09-26 |url-status=dead |archive-url=https://web.archive.org/web/20101209135705/http://www.metoffice.gov.uk/corporate/pressoffice/anniversary/computers.html |archive-date=2010-12-09}}</ref>

In 1954, with the decision to proceed with LEO II and interest from other commercial companies, Lyons formed LEO Computers Ltd.

The first LEO III was completed in 1961; it was a [[solid-state electronics|solid-state]] machine with a 13.2&nbsp;μs cycle time [[ferrite core memory]].<ref name="leo3s">{{Cite web |last= |first= |title=Leo III installations |url=http://www.leo-computers.org.uk/leo-3s.html |website=LEO Computers Society |date= |access-date=30 November 2021}}</ref> It was [[microcode|microprogrammed]] and was controlled by a [[Computer multitasking|multitasking]] "Master program" operating system, which allowed concurrent running of as many as 12 application programs.

Users of LEO computers programmed in two coding languages: [[Intercode]],<ref>{{cite journal |author-last=Berry |author-first=F. J. |title=Intercode, a Simplified Coding Scheme for AMOS |journal=The Computer Journal |date=1959-02-01 |volume=2 |issue=2 |pages=55–58 |doi=10.1093/comjnl/2.2.55 |issn=0010-4620 |others=AMOS - Ferranti Mark I*|doi-access= }}</ref> a low-level [[Assembly language|assembler]] type language; and CLEO ([[acronym]]: Clear Language for Expressing Orders), the [[COBOL]] equivalent.<ref>{{cite magazine|title=Creative Computing|url=https://books.google.com/books?id=83MqAAAAMAAJ|accessdate=4 June 2021|year=1985|magazine=[[Creative Computing (magazine)|Creative Computing]]|quote=learned a language called Cleo which was similar in many ways to Cobol}}</ref>

One of the features that LEO III shared with many computers of the day was a loudspeaker connected to the central processor via a divide-by-100 circuit and an amplifier which enabled operators to tell whether a program was looping by the distinctive sound it made.<ref>[http://www.leo-computers.org.uk LEO Computers Society website]</ref> Another quirk was that many intermittent faults were due to faulty connectors and could be temporarily fixed by briskly strumming the card handles.{{Citation needed|date=January 2016}}

Some LEO III machines purchased in the mid-to-late 1960s remained in commercial use at [[General Post Office|GPO]] Telephones, the forerunner of [[BT Group|British Telecom]], until 1981, primarily producing telephone bills.<ref name=":2" /><ref name="leo3s" /> They were kept running using parts from redundant LEOs purchased by the GPO.{{Citation needed|date=August 2011}}