Editing IBM mainframe (section)

==First and second generation==
[[File:IBM Electronic Data Processing Machine - GPN-2000-001881.jpg|thumb|right| IBM 704 mainframe at [[National Advisory Committee for Aeronautics|NACA]] in 1957]]

From 1952 into the late 1960s, IBM manufactured and marketed several large computer models, known as the [[IBM 700/7000 series]]. The [[Vacuum-tube computer|first-generation]] 700s were based on [[vacuum tube]]s, while the later, second-generation 7000s used [[transistor]]s. These machines established IBM's dominance in [[electronic data processing]] ("EDP"). IBM had two model categories: one (701, 704, 709, 7030, 7090, 7094, 7040, 7044) for engineering and scientific use, and one (702, 705, 705-II, 705-III, 7080, 7070, 7072, 7074, 7010) for commercial or data processing use. The two categories, scientific and commercial, generally used common peripherals but had completely different [[instruction set]]s, and there were incompatibilities even within each category.

IBM initially sold its computers without any software, expecting customers to write their own; programs were manually initiated, one at a time. Later, IBM provided [[compilers]] for the newly developed higher-level [[programming language]]s [[Fortran]], [[COMTRAN]] and later [[COBOL]]. The first [[operating systems]] for IBM computers were written by IBM customers who did not wish to have their very expensive machines (US$2M in the mid-1950s) sitting idle while operators set up jobs manually. These first operating systems were essentially scheduled work queues. It is generally thought the first operating system used for real work was [[GM-NAA I/O]], produced by [[General Motors]]' Research division in 1956. IBM enhanced one of GM-NAA I/O's successors, the [[SHARE Operating System]], and provided it to customers under the name [[IBSYS]].<ref name="frobeniusIBSYS">{{cite web| url = http://www.frobenius.com/ibsys.htm| title = IBM 7090/94 IBSYS Operating System| archive-url = https://web.archive.org/web/20210424184903/http://www.frobenius.com/ibsys.htm| archive-date = April 24, 2021}}</ref><ref name="UnisysHistNewsletterV1N3">{{cite journal
 | last         = Gray
 | first        = George
 | date         = March 1999
 | title        = EXEC II
 | periodical   = Unisys History Newsletter
 | volume       = 1
 | issue        = 3
 | url          = https://wiki.cc.gatech.edu/folklore/index.php/EXEC_II
 | archive-url  = https://web.archive.org/web/20170809171206/https://wiki.cc.gatech.edu/folklore/index.php/EXEC_II
 | archive-date = August 9, 2017}}</ref> As software became more complex and important, the cost of supporting it on so many different designs became burdensome, and this was one of the factors which led IBM to develop [[System/360]] and its operating systems.<ref name="Boyer360Revolution">{{cite web
 |     title = The 360 Revolution
 |     author = Chuck Boyer
 |     url = http://www.ibm.com/servers/eserver/au/zseries/download/360revolution_040704.pdf
 |     publisher = IBM
 |     access-date = December 22, 2020
 |     archive-date = July 1, 2023
 |     archive-url = https://web.archive.org/web/20230701114010/https://www.ibm.com/servers
 |     url-status = live
 }}</ref>

The [[Transistor computer|second generation]] (transistor-based) products were a mainstay of IBM's business and IBM continued to make them for several years after the introduction of the System/360. (Some [[IBM 7094]]s remained in service into the 1980s.)