Editing History of the Internet (section)

===Precursors===

==== Telegraphy ====
:The practice of transmitting messages between two different places through an electromagnetic medium dates back to the [[electrical telegraph]] in the late 19th century, which was the first fully digital communication system. [[Radiotelegraphy]] began to be used commercially in the early 20th century. [[Telex]] became an operational [[teleprinter]] service in the 1930s. Such systems were limited to [[Point-to-point (telecommunications)|point-to-point communication]] between two [[End system|end devices]].

==== Information theory ====
:Fundamental theoretical work in [[telecommunications]] technology was developed by [[Harry Nyquist]] and [[Ralph Hartley]] in the 1920s. [[Information theory]], as enunciated by [[Claude Shannon]] in 1948, provided a firm theoretical [[underpinning]] to understand the trade-offs between [[signal-to-noise ratio]], [[Bandwidth (computing)|bandwidth]], and error-free [[Transmission (telecommunications)|transmission]] in the presence of [[noise]].

==== Computers and modems ====
:Early fixed-program [[computer]]s in the 1940s were operated manually by entering small programs via [[Switch|switches]] in order to load and run a series of programs. As [[transistor]] technology evolved in the 1950s, [[central processing unit]]s and user [[Computer terminal|terminals]] came into use by 1955. The [[mainframe computer]] model was devised, and  [[modem]]s, such as the [[Bell 101 modem|Bell 101]], allowed [[digital data]] to be transmitted over regular unconditioned [[Telephone line|telephone lines]] at low speeds by the late 1950s. These technologies made it possible to exchange data between [[Remote desktop software|remote computers]]. However, a fixed-line link was still necessary; the point-to-point communication model did not allow for direct communication between any two arbitrary systems. In addition, the applications were specific and not general purpose. Examples included [[Semi-Automatic Ground Environment|SAGE]] (1958) and [[Sabre (travel reservation system)|SABRE]] (1960).

==== Time-sharing ====
:[[Christopher Strachey]], who became [[University of Oxford|Oxford University's]] first Professor of [[Computation]], filed a [[patent application]] in the United Kingdom for [[time-sharing]] in February 1959.<ref>{{Cite web|url=https://history.computer.org/pioneers/strachey.html|title=Computer Pioneers - Christopher Strachey|website=history.computer.org|access-date=2020-01-23}}</ref><ref name=":13">{{Cite web |title=Computer - Time-sharing, Minicomputers, Multitasking |url=https://www.britannica.com/technology/computer/Time-sharing-and-minicomputers |access-date=2023-07-23 |website=Britannica |language=en}}</ref> In June that year, he gave a paper "Time Sharing in Large Fast Computers" at the [[International Federation for Information Processing#History|UNESCO Information Processing Conference]] in Paris where he passed the concept on to [[J. C. R. Licklider]].<ref name="ctsspg">{{cite book|first=F. J. |last=Corbató |display-authors=etal |url=http://www.bitsavers.org/pdf/mit/ctss/CTSS_ProgrammersGuide.pdf |title=The Compatible Time-Sharing System: A Programmer's Guide |publisher=MIT Press |year=1963 |isbn=978-0-262-03008-3}}. "the first paper on time-shared computers by C. Strachey at the June 1959 UNESCO Information Processing conference".</ref><ref>{{harvnb|Gillies|Cailliau|2000|page=13}}</ref> Licklider, a vice president at [[BBN Technologies|Bolt Beranek and Newman, Inc.]] (BBN), promoted the idea of time-sharing as an alternative to [[batch processing]].<ref name=":13" /> [[John McCarthy (computer scientist)|John McCarthy]], at [[Massachusetts Institute of Technology|MIT]], wrote a memo in 1959 that broadened the concept of time sharing to encompass multiple interactive user sessions, which resulted in the [[Compatible Time-Sharing System]] (CTSS) implemented at MIT. Other multi-user mainframe systems developed, such as [[PLATO (computer system)|PLATO]] at the [[University of Illinois Chicago]].<ref>{{Cite web |title=Reminiscences on the Theory of Time-Sharing |url=http://jmc.stanford.edu/computing-science/timesharing.html |access-date=2020-01-23 |website=John McCarthy's Original Website |quote=in 1960 'time-sharing' as a phrase was much in the air. It was, however, generally used in my sense rather than in John McCarthy's sense of a CTSS-like object.}}</ref> In the early 1960, the [[Advanced Research Projects Agency]] (ARPA) of the [[United States Department of Defense]] funded further research into time-sharing at MIT through [[Project MAC]].