Execute Channel Program: Difference between revisions

Revision as of 15:09, 3 March 2018

Revision as of 15:21, 3 March 2018

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{{refimprove|date=June 2012}}

In [[IBM mainframe]] [[operating system]]s, '''Execute Channel Program''' ('''EXCP''') is a [[Supervisor Call instruction|supervisor call]] for low-level device access, where the programmer is responsible for providing a ''[[Channel program#Channel Program|channel program]]''—a list of device-specific commands ([[Channel command word#Channel command words|CCW]]s, that is, a [[Channel program#Channel Program|channel program]], to)—to be executed by I/O channels, control units and devices. EXCP is more specifically described in the OS System Programmer's Guide.<ref>{{cite manual|publisher=IBM|title=IBM System/360 Operating System System Programmer's Guide|id=C28-6550-2|date=March 1967|url=http://www.bitsavers.org/pdf/ibm/360/os/R01-08/C28-6550-2_OSsysPrmg_Mar67.pdf}}</ref>

==Specifying datasets==

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==Simplified operations on direct access datasets==

A variation of EXCP is [[Execute Direct Access Program|XDAP]] (XDAP), which is indeedused for accessing direct access storage, only, and is provided for reading and updating existing direct access storage records. XDAP cannot be used to add records, but XDAP can be utilized along with BSAM or BPAM to effect record additions to such datasets, and several OS components utilize XDAP in this manner (the Linkage Editor, IEWL, in particular).

==Telecommunications device access==