OS/360 was an operating system with batch processing ability that IBM for their System/360-Grossrechner in the year 1964 had announced. OS/360 belonged to non removable disks, voraussetzten.OS/360 to the first operating systems the mass storages with direct access, as a family consisting of three control programs was e.g. developed, each of the three control programs was both larger and with more functionality equipped. The simplest version, the PCP (Primary control Program), could the jobs task in each case implement and had thus sequentially work on. The next version, the MFT (multiprogramming with A Fixed NUMBER OF tasks), added the function range a limited multitasking. Only a firmly defined number of tasks could be at the same time implemented, which had necessary memory allocations for the jobs before the start of the job are firmly defined. The last version, the MVT (multiprogramming with A variable NUMBER OF tasks), permitted an implementing to any number of tasks, as well as a dynamic memory use by the tasks, i.e. task the assigned storage area could become larger or make smaller during the execution. OS/360 introduced also the JCL (job control LANGUAGE).

OS/360 was however late delivered, since it came with IBM to a combination of several organizational problems. The whole project was technically very fastidious and IBM had not yet the necessary experience in handling such large software projects. The originally planned distribution dates in the year 1965 for the simple version and in the year 1966 for the two other versions could not be kept. The PCP could be delivered only 1966 and the other versions only 1967.

OS/360 was developed further, when late hardware with the ability for virtual addressing for the System/370-Reihe one developed. From MFT OS/VS1 and MVT were renamed to OS/VS2, later OS/VS2 after further development in MVS (multiple Virtual STORAGE).

Today OS/360 is public domain and can be downloaded free of charge. Beside the original System/360-Hardware can OS/360 today also on Windows and Linux systems with the free Hercules emulator be implemented.

The development of the system is 50 million dollar to have cost. A code line of OS/360 was thus "“worth 225 dollar"”, to reported Fred Brooks, the manager of the project. The operating system is to have had constantly 1000 errors: for 1000 eliminated errors were added with each release of 1000 new errors, wrote once the quality manager OD Boehm.

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Articles in category "OS/360"

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• IBM 360/370/3090/390
  A condensed history of IBM mainframes and their operating systems from System/360 through System/390.


• Introduction to Generating and Running OS/360 on Hercules
  This is an introduction to getting IBM's OS/360 operating system loaded and running on the Hercules emulator for the System/370, ESA/390, and z/Architecture ...


• MVS... a long history : OS/360
  In April 1964, IBM announced OS/360, an operating system developed to support the new ... OS/360 included three control program options, delivered in stages ...


• Wikipedia OS/360 Encyclopedia Entry
  Short article with many embedded links describing Operating System/360 (OS/360), the original ancestor...