Access method: Difference between revisions

Revision as of 09:13, 18 January 2017

Revision as of 12:57, 8 September 2017

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{{refimprove|date=August 2012}}

An '''access method''' is a function of a [[mainframe computer|mainframe]] [[operating system]] that enables access to data on disk, tape or other external devices. They were introduced in 1963 in IBM [[OS/360]] operating system.<ref name=aus>[http://researchweb.watson.ibm.com/journal/rd/255/auslander.pdf M. A. Auslander, D. C. Larkin, A. L. Scherr: "The Evolution of the MVS Operating System", pages 478-479] {{webarchive |url=https://web.archive.org/web/20081119054653/http://researchweb.watson.ibm.com/journal/rd/255/auslander.pdf |date=November 19, 2008 }}</ref> Access methods provide an [[API|applicationapplic]]

ation [[API|programming interface (API)]] for programmers to transfer data to or from device, and could be compared to [[device driver]]s in non-mainframe operating systems.

== Purpose of access methods ==

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== IMS ==

The [[IBM Information Management System]] (IMS) uses the term "access method" to referefer to its methods for manipulating "segments in a database record". These are:

* [[Generalized Sequential Access Method]] ([[GSAM]]),

* [[Hierarchical Direct Access Method]] ([[HDAM (computing)|HDAM]]),