Microsoft KB Archive/88436

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Checksum for Object Module Records Can Be Zero

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Q88436

6.00 6.00a 6.00ax 7.00 | 6.00 6.00a | 1.00 1.50 1.51 1.52 MS-DOS | OS/2 | WINDOWS kbtool -- The information in this article applies to: - The Microsoft C/C++ Compiler (CL.EXE), included with: - Microsoft C for MS-DOS, versions 6.0, 6.0a, and 6.0ax - Microsoft C for OS/2, versions 6.0 and 6.0a - Microsoft C/C++ for MS-DOS, version 7.0 - Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, and 1.52 -- The Microsoft Object Module Format (OMF) consists of records that all have the same basic layout. At the end of each record is a byte that can be used as a checksum. The checksum byte can be set so that adding all bytes in the record, including the checksum byte, results in a sum mod 256 or zero. In Microsoft C 6.0, 7.0, and Visual C++ 1.0 the quick/fast compile (/qc or /f) feature produces .OBJ files that have the checksum byte set to zero. In both C 6.0, 7.0, and Visual C/C++ 1.0 the optimizing compiler produces .OBJ files that have the checksum set. Both techniques are valid ways of setting the value of the checksum byte. Additional reference words: kbinf 1.00 1.50 6.00 6.00a 6.00ax 7.00 8.00 8.00c KBCategory: kbtool KBSubcategory: CLIss

Keywords : kb16bitonly

Issue type :

Technology : kbVCsearch kbAudDeveloper kbCVCComp