Editing Conversational Monitor System (section)

==History==
CMS was originally developed as part of IBM's [[CP/CMS]] operating system. At the time, the acronym meant "Cambridge Monitor System" (but also: "Console Monitor System"). 
* CMS first ran under [[IBM CP-40|CP-40]], a one-off research system using custom hardware at IBM's [[Cambridge Scientific Center]]. Production use at CSC began in January 1967. The CMS user interface drew heavily on experience with the influential first-generation time-sharing system [[Compatible Time-Sharing System|CTSS]], some of whose developers worked on [[CP/CMS]]. (CTSS was used as an early [[CP/CMS]] development platform.)
* Later in 1967, [[CP/CMS]] became generally available on the [[IBM System/360 Model 67]], where, although the new control program [[CP-67]] was a substantial re-implementation of [[IBM CP-40|CP-40]], CMS remained essentially the same. IBM provided [[CP/CMS]] "as is" &ndash; without any support, in source code form, as part of the [[IBM Type-III Library]]. [[CP/CMS]] was thus an [[open-source software|open source]] system. Despite this lack of support from IBM, [[CP/CMS]] achieved great success as a time-sharing platform; by 1972, there were some 44 [[CP/CMS]] systems in use, including commercial sites that resold access to [[CP/CMS]].

In 1972, IBM released its [[VM (operating system)|VM/370]] operating system, a re-implementation of [[CP/CMS]] for the [[System/370]], in an announcement that also added [[virtual memory]] hardware to the [[System/370]] series. Unlike [[CP/CMS]], VM/370 ''was'' supported by IBM. VM went through a series of versions, and is still in use today as [[z/VM]].

Through all its distinct versions and releases, the CMS platform remained still quite recognizable as a close descendant of the original CMS version running under [[IBM CP-40|CP-40]]. Many key user interface decisions familiar to today's users had already been made in 1965, as part of the [[IBM CP-40|CP-40]] effort. See [[IBM CP-40#CMS under CP-40|CMS under CP-40]] for examples.

Both [[VM (operating system)|VM]] and [[CP/CMS]] had checkered histories at IBM. VM was not one of IBM's "strategic" operating systems, which were primarily the [[OS/360|OS]] and [[DOS/360|DOS]] families, and it suffered from IBM political infighting over [[time-sharing]] versus [[batch processing]] goals. This conflict is why [[CP/CMS]] was originally released as an unsupported system, and why VM often had limited development and support resources within IBM. An exceptionally strong user community, first established in the self-support days of [[CP/CMS]] but remaining active after the launch of VM, made substantial contributions to the operating system, and mitigated the difficulties of running IBM's "other operating system".