Browse Prior Art Database

Selective Address Compare

IP.com Disclosure Number: IPCOM000039702D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Jonas, B: AUTHOR

Abstract

This article relates to an improvement to the address compare function which allows any instruction in a program which erroneously modifies an area to be found. When wrong data is randomly set on a given area, for example, once a week, it is difficult to find the guilty instruction using the conventional address compare function. In a program, some memory areas, for example, the code, the tables or constants, must not be corrupted in any case. The address compare is a hardware tool which allows any instruction which wrongly modifies those areas to be detected. Other areas, for example, control blocks, dynamic tables, or save areas, are permanently modified. In that case, if an abnormal modification occurs, for example, one or several bits are ON or OFF once in a while, the hardware tool alone is unusable.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 92% of the total text.

Page 1 of 1

Selective Address Compare

This article relates to an improvement to the address compare function which allows any instruction in a program which erroneously modifies an area to be found. When wrong data is randomly set on a given area, for example, once a week, it is difficult to find the guilty instruction using the conventional address compare function. In a program, some memory areas, for example, the code, the tables or constants, must not be corrupted in any case. The address compare is a hardware tool which allows any instruction which wrongly modifies those areas to be detected. Other areas, for example, control blocks, dynamic tables, or save areas, are permanently modified. In that case, if an abnormal modification occurs, for example, one or several bits are ON or OFF once in a while, the hardware tool alone is unusable. The selective address compare is a software tool and a complement to the hardware tool. When a selective address compare is to be performed at a given address where any bit can be changed except a given bit, for example, bit 5 which must be always OFF, the solution to find which instruction raises the bit 5 is the following: An address compare is set at the given address, the option is "store data". A mask configuration is set which means bit 5 must be watched. A pattern is set which means process address compare only when bit 5 is ON. As soon as bit 5 raises, the address compare is processed. Otherwise, the address compare hit occurs b...