HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                        .EXE - DOS EXE File Structure

    Offset Size             Description

       00   word  "MZ" - Link file .EXE signature (Mark Zbikowski?)
       02   word  length of image mod 512
       04   word  size of file in 512 byte pages
       06   word  number of relocation items following header
       08   word  size of header in 16 byte paragraphs, used to locate
                    the beginning of the load module
       0A   word  min # of paragraphs needed to run program
       0C   word  max # of paragraphs the program would like
       0E   word  offset in load module of stack segment (in paras)
       10   word  initial SP value to be loaded
       12   word  negative checksum of pgm used while by EXEC loads pgm
       14   word  program entry point, (initial IP value)
       16   word  offset in load module of the code segment (in paras)
       18   word  offset in .EXE file of first relocation item
       1A   word  overlay number (0 for root program)

       - relocation table and the program load module follow the header
       - relocation entries are 32 bit values representing the offset
         into the load module needing patched
       - once the relocatable item is found, the CS register is added to
         the value found at the calculated offset

       Registers at load time of the EXE file are as follows:

       AX:     contains number of characters in command tail, or 0
       BX:CX   32 bit value indicating the load module memory size
       DX      zero
       SS:SP   set to stack segment if defined else,  SS = CS and
               SP=FFFFh or top of memory.
       DS      set to segment address of EXE header
       ES      set to segment address of EXE header
       CS:IP   far address of program entry point, (label on "END"
               statement of program)

Esc or Alt-X to exit EXE file header Home/PgUp/PgDn/End ←↑↓→
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