VM (operating system)

z/VM
Developer	IBM
OS family	VM family
Working state	Current
Source model	1972–1986 Open source, 1977–present Closed source
Initial release	1972
Latest release	IBM z/VM V7.2 / September 16, 2020
Marketing target	IBM mainframe computers
Available in	English
Platforms	System/370, System/390, zSeries, IBM zEnterprise System
License	1972–1981 Public domain, 1976–present Proprietary
Official website	www.vm.ibm.com

VM (often: VM/CMS) is a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers.

The following versions are known:

Virtual Machine Facility/370: VM/370, released in 1972, is a System/370 reimplementation of earlier CP/CMS operating system.

VM/370 Basic System Extensions Program Product: VM/BSE (BSEPP) is an enhancement to VM/370 that adds support for more devices (such as 3370-type fixed-block-architecture DASD drives), improvements to the CMS environment (such as an improved editor), and some stability enhancements to CP.

VM/370 System Extensions Program Product: VM/SE (SEPP) is an enhancement to VM/370 that includes the facilities of VM/BSE, as well as a few additional fixes and features.

Virtual Machine/System Product: VM/SP, a milestone version,^[1] replaces VM/370, VM/BSE and VM/SE. Release 1 added EXEC2 and XEDIT System Product Editor; Release 3 added REXX; Release 6 added the shared filesystem.
Virtual Machine/System Product High Performance Option ^[2]: VM/SP HPO adds additional device support and functionality to VM/SP, and allows certain S/370 machines that can utilize more than 16 MB of real storage to do so, up to 64 MB. This version was intended for users that would be running multiple S/370 guests at once.^[3]
Virtual Machine/Extended Architecture Migration Aid ^[4]: VM/XA MA is intended to ease the migration from MVS/370 to MVS/XA by allowing both to run concurrently on the same processor complex.
Virtual Machine/Extended Architecture System Facility ^[5]: VM/XA SF is an upgraded VM/XA MA with improved functionality and performance.
Virtual Machine/Extended Architecture System Product ^[6]: VM/XA SP is an upgraded VM/XA MA with improved functionality and performance, offered as a replacement for VM/SP HPO on machines supporting S/370-XA. It includes a version of CMS that can run in either S/370 or S/370-XA mode.
Virtual Machine/Enterprise Systems Architecture ^[7]: VM/ESA provides the facilities of VM/SP, VM/SP HPO and VM/XA SP. VM/ESA version 1 can run in S/370, ESA/370 or ESA/390 mode; it does not support S/370 XA mode. Version 2 only runs in ESA/390 mode. The S/370-capable versions of VM/ESA were actually their own separate version from the ESA/390 versions of VM/ESA, as the S/370 versions are based on the older VM/SP HPO codebase, and the ESA/390 versions are based on the newer VM/XA codebase.
z/VM^[8]

z/VM, the last version still widely used as one of the main full virtualization solutions for the mainframe market.^{[citation needed]} z/VM 4.4 was the last version that could run in ESA/390 mode; subsequent versions only run in z/Architecture mode.

The CMS in the name refers to the Conversational Monitor System, a component of the product that is a single-user operating system that runs in a virtual machine and provides conversational time-sharing in VM.

^ Elliott, Jim (August 17, 2004). The Evolution of IBM Mainframes and VM (PDF). SHARE August 2004. Linux for S/390 Linux for Big Iron. SHARE. Session 9140. Archived (PDF) from the original on October 13, 2006. Retrieved October 21, 2007.
^ VM/SYSTEM PRODUCT HIGH PERFORMANCE OPTION ANNOUNCED. Announcement Letters. IBM. October 21, 1981. ZP81-0805. Archived from the original on December 17, 2021. Retrieved December 17, 2021.
^ Cite error: The named reference :0 was invoked but never defined (see the help page).
^ VIRTUAL MACHINE/EXTENDED ARCHITECTURE MIGRATION AID. Announcement Letters. IBM. October 21, 1981. ZP81-0811. Archived from the original on December 17, 2021. Retrieved December 17, 2021.
^ VIRTUAL MACHINE/EXTENDED ARCHITECTURE (VM/XA) SYSTEMS FACILITY. Announcement Letters. IBM. February 12, 1985. 285-044. Archived from the original on December 17, 2021. Retrieved December 17, 2021.
^ VIRTUAL MACHINE/EXTENDED ARCHITECTURE SYSTEM PRODUCT (VM/XA SP) RELEASE 1. Announcement Letters. IBM. June 11, 1987. 287-239. Archived from the original on December 17, 2021. Retrieved December 17, 2021.
^ VIRTUAL MACHINE/ENTERPRISE SYSTEMS ARCHITECTURE VERSION 1 RELEASE 1.0 AND VERSION 1 RELEASE 1.1. Announcement Letters. IBM. September 5, 1990. 290-499. Archived from the original on December 17, 2021. Retrieved December 17, 2021.
^ z/VM V3R1 Enabled for 64-bit Architecture. Announcement Letters. IBM. October 3, 2000. 200-358. Archived from the original on December 17, 2021. Retrieved December 17, 2021.

[1] Elliott, Jim (August 17, 2004). The Evolution of IBM Mainframes and VM (PDF). SHARE August 2004. Linux for S/390 Linux for Big Iron. SHARE. Session 9140. Archived (PDF) from the original on October 13, 2006. Retrieved October 21, 2007.

[2] VM/SYSTEM PRODUCT HIGH PERFORMANCE OPTION ANNOUNCED. Announcement Letters. IBM. October 21, 1981. ZP81-0805. Archived from the original on December 17, 2021. Retrieved December 17, 2021.

[:0-3] Cite error: The named reference :0 was invoked but never defined (see the help page).

[4] VIRTUAL MACHINE/EXTENDED ARCHITECTURE MIGRATION AID. Announcement Letters. IBM. October 21, 1981. ZP81-0811. Archived from the original on December 17, 2021. Retrieved December 17, 2021.

[5] VIRTUAL MACHINE/EXTENDED ARCHITECTURE (VM/XA) SYSTEMS FACILITY. Announcement Letters. IBM. February 12, 1985. 285-044. Archived from the original on December 17, 2021. Retrieved December 17, 2021.

[6] VIRTUAL MACHINE/EXTENDED ARCHITECTURE SYSTEM PRODUCT (VM/XA SP) RELEASE 1. Announcement Letters. IBM. June 11, 1987. 287-239. Archived from the original on December 17, 2021. Retrieved December 17, 2021.

[7] VIRTUAL MACHINE/ENTERPRISE SYSTEMS ARCHITECTURE VERSION 1 RELEASE 1.0 AND VERSION 1 RELEASE 1.1. Announcement Letters. IBM. September 5, 1990. 290-499. Archived from the original on December 17, 2021. Retrieved December 17, 2021.

[8] z/VM V3R1 Enabled for 64-bit Architecture. Announcement Letters. IBM. October 3, 2000. 200-358. Archived from the original on December 17, 2021. Retrieved December 17, 2021.

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History of IBM mainframe operating systems
Early mainframe computer OSes GM OS & GM-NAA I/O (1955) BESYS (1957) UMES (1958) SOS (1959) IBSYS (1960) MIT CTSS (1961) 7040/7044 Operating System (16/32K) (7040-PR-150) 1410/7010 Operating System (1410-PR-155)
Miscellaneous S/360 line OSes BOS/360 (1965) TOS/360 (1965) TSS/360 (1967) MTS (1967) ORVYL (1967) RACS (1965) RAX (1966) MUSIC (1972) MUSIC/SP (1985)
DOS/360 and successors (1966) DOS/360 (1965) DOS/VS (1972) DOS/VSE (1979) VSE/AF (1979) VSE/SP (1983, 1985) VSE/ESA (1991) z/VSE (2005) VSEⁿ (2021)
OS/360 and successors (1966) MFT (1966) MFT II (1968) OS/VS1 (1972) OS/VS1 BPE MVT (1967) 65MP OS/VS2R1 (SVS) (1972) MVS (OS/VS2R2 and later) (1974) MVS/SE (1978) MVS/SE 2 (1979) MVS/SP Version 1 (1980) MVS/XA (1983) MVS/ESA (1988) OS/390 (1995) z/OS (2000)
VM line CP-40 /CMS (1967) CP-67 /CMS (1967) VP/CSS (1968) VM/370 (1972) VM/BSE (BSEPP) VM/SE (SEPP) VM/SP (1980) VM/XA MA (1984) VM/XA SF (1985) VM/XA SP (1988) VM/ESA (1990) z/VM (2000)
TPF line ACP (1967) TPF (1979) z/TPF (2005)
UNIX and Unix-like UTS (1981) AIX/370 (1990) AIX/ESA (1991) MVS/ESA OpenEdition (1993) VM/ESA OpenEdition (1995) OS/390 UNIX System Services (1996) Linux (1999) z/VM OpenExtensions (2000) z/OS UNIX System Services (2001) OpenSolaris (2008)
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