Function 4Dh (77)        Get Return Code of a Subprocess (WAIT)

    Gets the return code from a terminated subprocess.

       On entry:      AH         4Dh

       Returns:       AX         Return code

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    This function retrieves the return code from a process that has been
    terminated via Function 4Ch (EXIT) or Function 31h (Terminate and Stay
    Resident). There are two parts to the information returned: AL reports
    the return code issued by the terminating program itself; AH reports
    the manner in which it was terminated. The possible values in AH are:

         00h        normal termination
         01h        terminated via Ctrl-Break or Ctrl-C
         02h        terminated by DOS because of critical device error
         03h        terminated via Function 31h, Terminate and Stay Resident