Browse Prior Art Database

Redirected Interruptions

IP.com Disclosure Number: IPCOM000078248D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Baird, DP: AUTHOR

Abstract

CPU operation may be enhanced by providing for the automatic dispatching of selected programs when using SVC (Supervisor Call) instructions for the linkage between problem programs and system control programs.

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Redirected Interruptions

CPU operation may be enhanced by providing for the automatic dispatching of selected programs when using SVC (Supervisor Call) instructions for the linkage between problem programs and system control programs.

A register 20 is provided which defines a storage area 21 which may contain one or more pairs of P values to be compared against an inputted SVC parameter (P), and area 21 also contains corresponding pairs of PSWs (Program Status Words). If a fixed number of pairs is used, the register 20 need only specify a storage address (i.e. pointer). If a variable number of pairs is provided, the number of pairs to be used must be specified in register 20.

A latch 23 can be set by the system control program to enable or disable the use of the special SVC facility, if the CPU is to operate with control programs not designed to work with the facility.

In storage area 21, two pairs of SVC parameters are denoted as P(R1), P(C1) and P(R2), P(C2); the two pairs of PSWs are denoted as Old PSW(1), New PSW(1) and Old PSW(2) New PSW(2). A problem program can call a system program by executing a SVC, having a parameter value equal to P(C1) or P(C2). The return from the system program to the problem program is accomplished by executing another SVC, with a parameter value equal to P(R1) or P(R2). Each SVC is interpreted by the method in the illustrated flow diagram, which executes a comparison with steps 1, 2, 3 or 4 between the inputted parameter P and th...