The Conversational Monitor System (CMS) is a relatively simple interactive computing single-user operating system which was for many years IBM's principal time-sharing product. CMS runs primarily on IBM mainframe computers on top of the VM virtual machine operating system. Each CMS user appears to have their own personal operating system on their own private computer. The pair form a standard product, VM/CMS. In computer science, interactive computing refers to software which accepts input from humans -- for example, data or commands. ... An operating system (OS) is an essential software program that manages the hardware and software resources of a computer. ... For other uses, see IBM (disambiguation). ... Alternate uses: see Timesharing Time-sharing is an approach to interactive computing in which a single computer is used to provide apparently simultaneous interactive general-purpose computing to multiple users by sharing processor time. ... Mainframes (often colloquially referred to as big iron) are large and expensive computers used mainly by government institutions and large companies for legacy applications, typically bulk data processing (such as censuses, industry/consumer statistics, ERP, and bank transaction processing). ... VM is an early and influential virtual machine operating system from IBM, apparently the first true virtual machine system. ... In general terms, a virtual machine in computer science is software that creates a virtualized environment between the computer platform and the end user in which the end user can operate software. ... VM/CMS (Virtual Machine/Conversational Monitor System, originally called CP/CMS when it first appeared) is a bundled pair of operating systems used on IBM System/360, System/370, System/390, zSeries, and System z9 mainframes (and compatible systems). ...

CMS provides users an environment for running applications or batch jobs, manage data files, create and debug applications, and communicate with other systems or users. Application software is a loosely defined subclass of computer software that employs the capabilities of a computer directly to a task that the user wishes to perform. ... Look up batch in Wiktionary, the free dictionary. ... File has several meanings: Computer file File (tool) file (Unix), a program used to determine file types. ... Debugging is a methodical process of finding and reducing the number of bugs, or defects, in a computer program or a piece of electronic hardware thus making it behave as expected. ...

The acronym CMS originally stood for Cambridge Monitor System, after the IBM laboratory (the Cambridge Scientific Center) where it was developed; it was later renamed by IBM when VM/370 became an official IBM product in 1972.

CMS was developed in concert with VM to provide a time-sharing system; its original form was heavily influenced by CTSS, which was built by people at the same location (at MIT) as CSC. CTSS was actually used to develop initial versions of CMS software, using cross assemblers. CTSS, which stood for the Compatible Time-Sharing System, was one of the first time-sharing operating systems; it was developed at Project MAC at MIT. CTSS was first published, as well as operated in a time-sharing environment, in 1961; in addition, it was the system with the first... Mapúa Institute of Technology (MIT, MapúaTech or simply Mapúa) is a private, non-sectarian, Filipino tertiary institute located in Intramuros, Manila. ... This article is about a computing term. ...

Users log in to VM, providing a userid and password, and then boot their own virtual machine. This is done by issuing the command 'IPL CMS' ("IPL" stands for "initial program load"; standard IBM jargon for booting a machine), though this is normally done automatically for the user. Personal customization is done by a standard shell script file named 'PROFILE EXEC', which sets up user-specified environmental defaults, such as which disks and libraries are accessed. It has been suggested that System partition and boot partition be merged into this article or section. ...

While CMS started in the era of paper line terminals, by the late '1970s most users were connecting with full-screen terminals such as the IBM 3270. Unlike dumb terminals, they have local buffer storage and minimal processing abilities to deal with an entire screen of information at a time. The terminal deals with information in its buffer during editing. This enhances overall system performance because the mainframe doesn't have to deal with every keystroke typed by a user; the entire set of updated screen fields is transmitted to the mainframe when the ENTER key or a program function key is pressed. The 1970s decade refers to the years from 1971 to 1980, inclusive. ... Clemson Universitys library catalog as displayed in a 3270 emulation program The IBM 3270 is a class of terminals made by IBM (known as Display Devices) normally used to communicate with IBM mainframes. ... A dumb terminal in computing consists of a computer screen and keyboard, but practically no processing ability. ...

CMS garnered a very good reputation for being efficient and having good human factors for ease of use, relative to the standards of the time and prior to "GUI" environments such as are commonly used today. It was not uncommon to have hundreds of concurrent CMS interactive users on the same VM mainframe, with sub-second response times for the most common, "trivial" functions. Users program in FORTRAN, PL/I, APL, or the scripting language REXX, or use commercial software packages such as SAS. At one time, CMS was a major environment for e-mail and office productivity, using the IBM product PROFS, which was later renamed OfficeVision. Fortran (also FORTRAN) is a general-purpose[1], procedural[2], imperative programming language that is especially suited to numeric computation and scientific computing. ... PL/I (Programming Language One, pronounced pee el one) is an imperative computer programming language designed for scientific, engineering, and business applications. ... APL is an abbreviation, acronym, or initialism that may refer to: Acute promyelocytic leukemia, a subtype of acute myelogenous leukemia American President Lines, a Singapore-based container transportation and shipping company American Protective League, a WWI era pro-war organization Association of Pension Lawyers APL programming language, an array programming... REXX (REstructured eXtended eXecutor) is an interpreted programming language which was developed at IBM. It is a structured high-level programming language which was designed to be both easy to learn and easy to read. ... The SAS System, originally Statistical Analysis System, is an integrated system of software products provided by the SAS Institute that enables the programmer to perform: data entry, retrieval, management, and mining report writing and graphics statistical and mathematical analysis business planning, forecasting, and decision support operations research and project management... OfficeVision is an IBM proprietary office support application that runs on IBMs VM operating system and its user interface CMS. (Other platform versions may have been available but were not popular. ... OfficeVision is an IBM proprietary office support application that runs on IBMs VM operating system and its user interface CMS. OfficeVision provides email, shared calendars, and shared document storage and management, and it provides an ability to link to other applications such as word/text editors. ...

Two of the commonly used CMS tools include the editor XEDIT and the REXX programming language. Both of these products have been ported to other platforms and are now widely used outside the mainframe environment. A visual editor for VM/CMS using block mode IBM 3270 terminals. ... REXX (REstructured eXtended eXecutor) is an interpreted programming language which was developed at IBM. It is a structured high-level programming language which was designed to be both easy to learn and easy to read. ...

CMS is still in development and wide use today.

See also

• VM/CMS for the history of the development of the entire system, including VM

VM/CMS (Virtual Machine/Conversational Monitor System, originally called CP/CMS when it first appeared) is a bundled pair of operating systems used on IBM System/360, System/370, System/390, zSeries, and System z9 mainframes (and compatible systems). ...

Further reading

• Melinda Varian, VM and the VM Community: Past, Present, and Future (available here) is an excellent detailed history, starting with the experimental precursor to VM

External links

• The IBM 360/67 and CP/CMS