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Format to Hex Code to Object Code With Computed Checksum

IP.com Disclosure Number: IPCOM000058110D
Original Publication Date: 1988-Aug-01
Included in the Prior Art Database: 2005-Feb-15

Publishing Venue

IBM

Related People

Authors:
Greene, WB Strunk, JR [+details]

Abstract

This article describes a technique wherein the hex code for an engineering change (ECHG) program is formatted into object code that can be loaded into RAM and then be executed. A special checksum is calculated to allow a check to be made whenever the code is moved (i.e., sent to another location), verifying none of the bits are changed. The output of the INTEL* assembler for the 8031/8051 is a hexadecimal format that cannot be loaded and executed. The ECHG program reads in the hex code file, strips off the unnecessary information, stores the meaningful data and computes a special checksum. This checksum is then stored in the last byte of each page (256-byte segment). If the start of the code was at address x'0800', then the first checksum would be stored at address x'08FF'.