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Method for Detecting a Copy of a Previously Loaded Program

IP.com Disclosure Number: IPCOM000064161D
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18

Publishing Venue

IBM

Related People

Authors:
Bracht, CJ Camp, LS Fichtner, LG Haber, JG [+details]

Abstract

A method is described that allows Personal Computer operators to reinitiate a program without having multiple copies resident in memory. The method involves storing a unique signature in the program's Program Segment Prefix so that when it is found in memory, the program already exists in memory and another copy is not loaded. When the operator initiates the program, a scan of memory for the unique signature is performed. Since every program loaded into the Personal Computer's memory is loaded on a 16-byte boundary, the signature is also stored on a 16-byte boundary. This allows the signature scan to move in increments of 16 bytes rather than one byte looking for a match, thus greatly reducing the time spent scanning.