公开(公告)号：CA1092714A

公开(公告)日：1980-12-30

申请号：CA291137

申请日：1977-11-17

Applicant: IBM

Inventor： BROWN PAUL J ,  DUGAN ROBERT J ,  GUYETTE RICHARD R ,  STRONG DAVID L

IPC: G06F9/48 ,  G06F9/19

Abstract: EXTENDED INTERRUPTION HANDLING . A program instruction designated TEST PENDING INTERRUP TION (TPI) provides for recursive handling of non-specific interruptions in a specific class of interruptions without displacement of program status or environmental information. The instruction is located at a "terminal" position in a supervisory program for handling interruptions in the specific class. Its execution operates to set a condition code, clear an active request for interruption in the specific class (if at least one request in said class is pending) and store information accessible to the program identifying the source of the cleared request. Although the system controls for accepting non-specific interruption may be disabled during execution of any instruction such disability does not affect execution of this instruction. The condition code set by the instruction enables the associated supervisory program either to return control to an interrupted program (if no request is pending in the class) or to branch to a "relatively short" subroutine for attending directly to the event associated with the request cleared by the instruction. Since the instruction is executed only at a predetermined stage of the supervisory program, and only when the system controls are in a "known" state, many operations otherwise needed for handling unscheduled interruptions are not needed when TPI is used. Consequently the program and subroutine associated with TPI "recursion" can be much shorter (use far fewer instructions) than existing program operations for recursevely handling interruptions.