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Revision as of 17:31, 7 May 2019 view source Triple (talk \| contribs) 4 edits m Added a small amount of information and made nicer to read. ← Older edit		Latest revision as of 20:37, 10 July 2023 view source osdev>Khaledhammouda No edit summary
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Line 8: COM files were used by MS-DOS. They are raw binaries, meaning there is no header data. Also, COM files are restricted to the size of one segment (a real-address mode segment, 64kb), minus 256 bytes. When a COM file is loaded, it is assumed that all code and data fits in one segment, and it is loaded to offset 0x100. MS-DOS creates and stores an info structure starting at offset 0 and ending just before 0x100, called the Program Segment Prefix (PSP). The PSP is made just before starting the COM program. More info about the PSP can be found [https://web.archive.org/web/20061101031637/http://heim.ifi.uio.no/~stanisls/helppc/program_segment_prefix.html here]. PSP is only required for running DOS programs. COM files usually terminate with a RET instruction. On ~~The operating system starts~~DOS, the ~~COM~~RET ~~program using~~pops a ~~CALL~~empty ~~instruction,~~word sofrom ~~RET~~the ~~returns~~stack, towhich ~~the~~results ~~OS,~~in ~~allowing~~a ~~any~~interrupt ~~cleanup~~0x20 (~~like~~DOS ~~restarting~~API ~~the command prompt~~Exit) ~~to be handled by the~~being OScalled. ===Loading=== Line 21: ====32 bit==== *[[PE]] [[Category:Executable Formats]]