IBM MASM exit

stack    segment   stack
         db        80h dup(?)
stack    ends

data     segment
data     ends

code     segment

main     proc far
         push ds                 ; DS = PSP, save PSP segment on stack

         ; Insert program code here.
         ; Make sure the stack is balanced when finished
         ; -----------------
         assume cs:code,ds:data
         mov dx, @data
         mov ds, dx
         ; -----------------

         ; Exit EXE program with FAR Return to PSP_Segment:0000h where
         ; an Into 20h resides in the word at offset 0000h in the PSP

         xor ax, ax              ; AX = 0
         push ax                 ; Push 0 on the stack
                                 ; Note: `PUSH` with an immediate value
                                 ; wasn't a valid instruction on
                                 ; Intel 8088/8086 processors

         ; At this point the DS (PSP) pushed at the beginning of the program
         ; and the value 0000h forms a CS:IP FAR pointer on the stack

         ret                    ; Return to PSP_Segment:0000h via FAR pointer
                                 ; on the stack and execute
                                 ; the Int 20h at that address
main     endp
code     ends

         end