Editing History of the Internet (section)

==== 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).