Revision as of 01:57, 23 March 2021 edit Peter Flass (talk \| contribs) Autopatrolled, Extended confirmed users 19,403 edits →Relationship to supervisor: tcb vs srb ← Previous edit		Revision as of 06:30, 23 March 2021 edit undo Chatul (talk \| contribs) Extended confirmed users 8,448 edits →Relationship to supervisor: SRB mode only exists in MVS Next edit →
Line 85: ==Relationship to supervisor== EXCP's front-end is always in [[Task Control Block]] (TCB) mode, The normal mode for applications,<ref name="SoftwareAG">{{cite web \|last1=Software AG \|title=Natural zIIP Processing: TCBs, SRBs and Enclaves\| url=https://documentation.softwareag.com/natural/nat825mf/ziip/naz-nat-processing.htm \|access-date=Mar 22, 2021}}</ref> as EXCP is a Type 1 [[Supervisor Call instruction\|SVC]]. In MVS/370 and subsequent instances of the OS, the EXCP processor invokes [[Start Input/Output\|STARTIO]] to schedule execution of the channel program. Although the EXCP processor's back-end is always in [[Service Request Block]]{{efn\|In OS/360, OS/VS1 and SVS there is no SRB mode and appendages run with interrupts disabled.}} (SRB) mode,<ref name=SoftwareAG /> the back-end contains emulation code which allows the appendages developed for earlier, pre-MVS instances of the OS, specifically for EXCP, to function largely as before and thereby to appear to be in TCB mode, for which these appendages were originally designed. This distinction can complicate conversion of certain roll-your-own access methods and applications to MVS. ==Channel programs==

Execute Channel Program: Difference between revisions