Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

 ◄Detail► ◄Example►                          ◄Up► ◄Contents► ◄Index► ◄Back►
────────────────────────────────────────────────────────────────────────────
 
  Interrupt:   21h     Function:   4Bh
 
  Title:       Execute Program (EXEC)
 
  See also:    Get Return Code, File Control Block (FCB)
 
  Description:
 
     Allows an application program to run another program, regaining
     control when it is finished. This function can also be used to
     load overlays, although this use is uncommon.
 
     Input                                   Output
 
     AH = 4Bh                                If function successful
     AL = Subfunction                          Carry flag: clear
          00h = Load and Execute Program     All registers except for
          03h = Load Overlay                 CS:IP may be destroyed
     ES:BX = segment:offset of parameter     [Version 3.0+] Registers
             block                           are preserved in the
     DS:DX = segment:offset of program       usual fashion
             specification
                                             If function unsuccessful
                                               Carry flag: set
                                               AX = Error code (01h,
                                                    02h, 03h, 05h, 08h,
                                                    0Ah, or 0Bh)
                                               See: ◄Error codes►
                                    -♦-