IBMs flagship mainframe operating system. Began as OS/VS2 - an operating system for the System/360 mainframe based on OS/360. in the early 1970s. Eventually became MVS in 1974. Name was then changed to MVS/SE, and then MVS/SP. Addressing was expanded from 24 to 31 bits in 1983, and the name was changed to MVS/XA. Changed again to MVS/ESA in 1988. MVS and other components required to run a system (including TSO, VTAM and DFP) were bundled together to a new operating system, OS/390, in 1995.
Converted to a 64 bit operating system in 2000, and renamed again to z/OS. A variant, z/OSe was also released for 'new' workloads (eg. Java, DB2 and Websphere Application Server, but not IMS or COBOL) in 2002 (z/OSe 1.3). z/OSe discontinued in 2009 (z/OSe 1.8), and replaced with alternative pricing for the base z/OS product.
z/OS remains the world's most popular mainframe operating system, boasting leading security, reliability and performance.
IBM Product IDs:
- z/OS 2.x Product ID: 5650-ZOS
- z/OS 1.x Product ID: 5694-A01
- z/OSe 1.x Product ID: 5655-G52
- OS/390 2.x Product ID: 5647-A01
- OS/390 1.x Product ID: 5645-001
- MVS/ESA V5.xProduct ID: 5655-058 (with JES2)
- MVS/ESA 5.x Product ID; 5655-057 (with JES3)
- MVS/ESA 4.x Product ID: 5695-047 (with JES2)
- MVS/ESA 4.x Product ID: 5695-048 (with JES3)
- MVS/ESA 3.x Product ID: 5685-001 (with JES2)
- MVS/ESA 3.x Product ID: 5685-002 (with JES2)
- MVS/XA 2.x Product ID: 5740-XC6
- MVS/SP 1.x Product ID: 5740-XYS (with JES2)
- MVS/SP 1.x Product ID: 5740-XYN (with JES3)
- MVS/SE Product ID: 5740-XE1