Browse Prior Art Database

Console Controlled Address Compare Stop Function

IP.com Disclosure Number: IPCOM000044700D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Finkenaur, JK: AUTHOR

Abstract

In a processor which does not provide a hardware address-compare- stop facility, it is possible to implement such a facility in console microcode that will allow debug as if there were a hardware address compare stop. A console controlled address-compare-stop replaces a selected instruction with another instruction that causes or simulates a stop. The replaced instruction is tucked away in a predetermined location to allow the instruction stream to continue under the manual control of the micro- programmer. The replaced instruction is then examined to determine if it uses facilities that are sensitive to the time when the instruction is executed, and those facilities are reestablished in a setup instruction custom-built by the console processor.

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Console Controlled Address Compare Stop Function

In a processor which does not provide a hardware address-compare- stop facility, it is possible to implement such a facility in console microcode that will allow debug as if there were a hardware address compare stop. A console controlled address-compare-stop replaces a selected instruction with another instruction that causes or simulates a stop. The replaced instruction is tucked away in a predetermined location to allow the instruction stream to continue under the manual control of the micro- programmer. The replaced instruction is then examined to determine if it uses facilities that are sensitive to the time when the instruction is executed, and those facilities are reestablished in a setup instruction custom-built by the console processor.

The instruction replacing the instruction at the compare- stop address can simply branch to itself. To restart the program, the console micro-processor causes a control-store-transfer which, in turn, causes a branch to the location of the setup instruction which, in turn, branches to the location where the original instruction is saved. Following the branch, instruction execution will resume until the time that the compare stop is reached again, at which time the processor will hang on the compare-stop-replacement instruction again.

Disclosed anonymously

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