Note: This API call is for DOS personality only. Use Family API for portability.
Int 21H, AH=4DH
2 and higher
GET RETURN CODE (ERRORLEVEL)
AH = 4Dh
AH = termination type 00h normal (INT 20,INT 21/AH=00h, or INT 21/AH=4Ch) 01h control-C abort 02h critical error abort 03h terminate and stay resident (INT 21/AH=31h or INT 27) AL = return code CF clear
the word in which DOS stores the return code is cleared after being read by this function, so the return code can only be retrieved once COMMAND.COM stores the return code of the last external command it executed as ERRORLEVEL this call should not be used if the child was started with AX=4B04h; use AH=8Ah instead the following sequence will close a Virtual DOS Machine under OS/2 2.0 through OS/2 Merlin (but may change in the future): MOV AH,4Dh INT 21h HLT DB 02h,0FDh This sequence is the only way to close a specific VDM which was booted from floppy or a disk image.
Text based on Ralf Brown Interrupt List Release 61