MFT (operating system)

From Wikipedia, the free encyclopedia

It has been suggested that this article or section be merged into OS/360 and successors. (Discuss)

History of IBM mainframe operating systems

IBSYS 1950s CTSS 1961 BOS/360 1965 TOS/360 1965 TSS/360 1967 MUSIC/SP 1960s MTS 1970s

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

OS/360 and successors 1966 MFT 1966 OS/VS1 1970s MVT 1967 OS/VS2R1 (SVS) 1972 MVS (OS/VS2R2) 1974 MVS/370 1970s MVS/XA 1980s 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/SP 1980 VM/ESA 1988 z/VM 2000

TPF line ACP 1967 TPF 1979 z/TPF 2000s

Unix-like on IBM mainframes UTS 1981 AIX/370 1990 AIX/ESA 1991 Linux 1999

This box: view • talk • edit

In the history of IBM mainframe operating systems, multiprogramming with a fixed number of tasks (MFT) was one of the three available configurations of the OS/360's control program.^[1] In turn, OS/360 was an operating system for the IBM System/360 line of computers.

MFT was intended to serve as a stop-gap until MVT, the intended "target" configuration of OS/360, became available in 1967. Early versions of MVT had many problems, so simpler MFT continued to be used for many years. After introducing new System/370 machines with virtual memory, the MFT was developed in 1972 into OS/VS1, the last system of this particular line.

The earliest variant of OS/360's control program was the Primary Control Program (PCP). Next, there came two versions of MFT. The first shared much of the code and architecture with PCP, and was limited to four partitions. It was very cumbersome to run multiple partitions. The second version (MFT-II) changed much of the underlying code in the operating system, and was much more flexible to run. The number of partitions increased as well.

Later modifications of MFT-II added sub-tasking, so that the fixed number of tasks was no longer fixed, although the number of partitions did remain a limitation.

Although officially PCP, MFT and MVT were not a separate operating systems from OS/360,^[1] those were only an install-time configuration options—in today's words, a three different variants of OS kernel—because of quite different behaviour and memory requirements, users commonly considered them de facto separate operating systems, and referred to them as early OS/360, OS/MFT, OS/MVT, respectively.

[edit] References