DOS/360
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DOS/360 (Disk Operating System/360, commonly just: DOS) was an operating system announced by IBM, on the last day of 1964, for low-end System/360 computers. It was first delivered in June 1966.[1]
DOS was designed to have a very small memory footprint, and was able to run on 16KB machines, a configuration available on the low-end S/360-30. IBM had originally committed to delivering OS/360 on every S/360, including these small platforms; but due to a famous series of problems, IBM was forced to offer three additional systems:
In the meantime, the OS/360 project fell further and further behind schedule, described at length by Fred Brooks. When OS was finally released, a year late, it required at least a 64K machine.
Unlike OS/360, DOS/360 was a single-job system, i.e. it did not incorporate multitasking (though a version with limited multitasking was later released, for S/360 systems with at least 32K). It used three memory partitions, but it had no serious memory protection. The three partitions were not specialised, but frequently one was used for spooling punched cards to disk, another one for batch job execution, and another for spooling disk to printers.
With DOS/VS, introduced in 1972 when virtual memory was added to the System/370 series, the number of partitions was increased, virtual memory was introduced, and the minimum memory requirements increased.
Later, IBM released DOS/VSE, VSE/ESA, and z/VSE. DOS/360 successors are still alive as of 2006, though not as popular as its early days – when DOS became the most widely used operating system in the world.[2]
[edit] Miscellany
- Contrary to the Hacker's Jargon File, GECOS was not copied from DOS/360.
- Though both called simply "DOS", there is no relationship between DOS/360 and MS-DOS. This is common knowledge in the industry, but is sometimes a surprise to non-technicians.
[edit] References
- ^ E.W. Pugh, L.R. Johnson, and John H. Palmer, IBM's 360 and early 370 systems, MIT Press, Cambridge MA and London, ISBN 0-262-16123-0
– extensive (819 pp.) treatment of IBM's offerings during this period - ^ Pugh, op. cit., p. 331 – most widely used OS
External links
- Disk Operating System — Entry in the FOLDOC
This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.
