Multiprogramming with a Variable number of Tasks

History of IBM mainframe operating systems

On early mainframe computers: GM OS & GM-NAA I/O 1955 BESYS 1957 UMES 1958 SOS 1959 IBSYS 1960 CTSS 1961 On S/360 and successors: BOS/360 1965 TOS/360 1965 TSS/360 1967 MTS 1967 ORVYL 1967 MUSIC 1972 MUSIC/SP 1985

DOS/360 and successors 1966 DOS/VS 1972 DOS/VSE 1980s VSE/SP late 1980s VSE/ESA 1991 z/VSE 2005

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 Linux 1999 OpenSolaris 2008 z/OS UNIX System Services

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Multiprogramming with a Variable number of Tasks (MVT) was the most sophisticated of three available configurations of OS/360's control program.^[1] In turn, OS/360 was an operating system for the IBM System/360 line of computers. MVT was intended for the largest machines in the System/360 family, introduced in 1964, but it did not become available until 1967. Early versions had many problems and the simpler MFT continued to be used for many years.

In later decades, MVT had been developed into MVS, then OS/390, and now z/OS.

Officially PCP, MFT and MVT were not separate operating systems, but rather three different configuration variants of the same OS/360 code base.^[1] Because of quite different capabilities, system managers commonly considered them separate offerings, referring to them as early OS/360, OS/MFT, OS/MVT, respectively.

References

1. ^ ^{a b} IBM (1972) (PDF). OS/360 Introduction. IBM Systems Reference Library. pp. 50–51. GC28-6534-3. http://bitsavers.org/pdf/ibm/360/os/R21.0_Mar72/GC28-6534-3_OS360_Introduction_R21_Jan72.pdf. Retrieved 2007.  "there are two configurations of the [OS/360] control program: ... MVT configuration"

Further reading

Manuals

• IBM, "MVT Guide" - GC28-6720-4, R21, March 1972
• IBM, "MVT Supervisor PLM" - GY28-6659-7, Program Logic Manual, March 1972
• IBM, "OS I/O Supervisor PLM" - GY28-6616-9, Program Logic Manual, R21.7, April 1973

Books

• Brooks, Jr., Frederick P. (1975). "The Mythical Man-Month: Essays on Software Engineering", Addison-Wesley. ISBN 0-201-00650-2. (Reprinted with corrections, January 1982)
• Pugh, Emerson W.; Johnson, Lyle R.; Palmer, John H. (1991). IBM's 360 and Early 370 Systems, Cambridge : MIT Press. (pp. 291–345)