OS/360 - Revision history

Jnc: avoid dab

2022-09-09T12:59:11Z

avoid dab

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2018-12-26T22:53:10Z

wrong target

Jnc: A good start

2018-12-26T21:48:08Z

A good start

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'''OS/360''' was a [[batch]] [[operating system]] created by [[International Business Machines|IBM]] for the then-new [[IBM System/360]] line. It is perhaps best known now for being the project that prompted Fred Brooks to write his famous book, ''The Mythical Man-Month''.

OS/360 originaly came in three forms, each with different capabilities, and suitable for different [[hardware]] configurations:

* Primary Control Program (PCP) - intended for the smallest configurations, it only ran one [[job]] at a time; dropped in later versions of OS/360
* Multiprogramming with a Fixed number of Tasks (MFT) - intended as a temporary stop-gap until the last form ('''MVT''') was available, the first version was effectively PCP with support for 4 simultaneous jobs
* Multiprogramming with a Variable number of Tasks ('''MVT''') - the original target of OS/360, it took several years to get running reasonably well

MVT had issues with [[main memory]] fragmentation, caused by the fact that the 360 did not provide each [[process]] with its own [[address space]], but instead used [[protection key]]s; if a process was [[swapping|swapped]] out, it had to be reloaded into the exact same location in memory.

Due to the delays in getting OS/360 out, IBM provided several stop-gap OS's for use on 360's:

* BOS/360 (Basic Operating System)
* TOS/360 (Tape Operating System), which supported systems withj only [[magnetic tape drive]]s for [[secondary storage]]
* DOS/360 (Disk Operating System), a [[disk operating system]], a descendant of which is still in use

OS/360 was originally written entirely in [[assembly language]].

[[Category: IBM Operating Systems]]

← Older revision		Revision as of 12:59, 9 September 2022
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−	'''OS/360''' was a [[batch]] [[operating system]] created by [[International Business Machines\|IBM]] for the then-new [[IBM System/360]] line. It is perhaps best known now for being the project that prompted Fred Brooks to write his famous book, ''The Mythical Man-Month''.	+	'''OS/360''' was a [[batch operating system\|batch]] [[operating system]] created by [[International Business Machines\|IBM]] for the then-new [[IBM System/360]] line. It is perhaps best known now for being the project that prompted Fred Brooks to write his famous book, ''The Mythical Man-Month''.

	OS/360 originaly came in three forms, each with different capabilities, and suitable for different [[hardware]] configurations:		OS/360 originaly came in three forms, each with different capabilities, and suitable for different [[hardware]] configurations:

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 * Primary Control Program (PCP) - intended for the smallest configurations, it only ran one [[job]] at a time; dropped in later versions of OS/360
-* Multiprogramming with a Fixed number of Tasks (MFT) - intended as a temporary stop-gap until the last form ('''MVT''') was available, the first version was effectively PCP with support for 4 simultaneous jobs
+* Multiprogramming with a Fixed number of Tasks ('''MFT''') - intended as a temporary stop-gap until the last form (MVT) was available, the first version was effectively PCP with support for 4 simultaneous jobs
 * Multiprogramming with a Variable number of Tasks ('''MVT''') - the original target of OS/360, it took several years to get running reasonably well