Execute Channel Program in Real Storage: Difference between revisions

Revision as of 23:47, 17 June 2024

Latest revision as of 08:39, 27 July 2025

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==Relationship to Execute Channel Program (EXCP)==

EXCPVR may be viewed, historically, as a V=R (i.e., Virtual=Real) version of [[Execute Channel Program|EXCP]]. However, EXCPVR is not restricted to V=R applications. Indeed, EXCPVR may refer to non-V=R data areas provided such data areas are "fixed" and the channel command words which reference such data areas have been translated from virtual to real addresses by the programmer using the LRA [ Load Real Address ] privileged instruction, as the data channels deal only with real addresses{{efn|Except for 4300 machines equipped with ECPS:VSE}}, not virtual addresses. EXCPVR was first introduced in SVS and was continued in MVS/370.

==Support for Format 1 CCWs==