(.exe) DOS EXE File Structure

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Offset	Size	Description
00	word	"MZ" - Link file .EXE signature
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 paragraphs)
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 paragraphs)
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

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)