DOS Fn 4b03H: Load Overlay

                                                         Compatibility: 2.0+ 
 Expects: AX    4b03H
          DS:DX address of an ASCIIZ filespec of the program file to load
          ES:BX address of an ExecOverlayRec
 Returns: AX    error code if CF is set to CY
    Info: This function loads a program into memory at a desired location.
          It performs all needed segment fixups in preparation for
          executing the code, but does not actually begin execution.

          DS:DX points to an ASCIIZ string in the form...
          If the drive or path is omitted, defaults are assumed.

          ES:BX points to a block of memory prepared as an ExecOverlayRec
          that has been filled with the information needed, including the
          address to load the overlay.

   Notes: ■ This variation of the EXEC function is used to load program
            fragments, such a code overlays.  It does not prepare a PSP nor
            does it set registers as they would be expected by a stand-
            alone program.

          ■ There must be enough free memory for DOS to load the program.

See Also: Fn 4b01H (load program)
          Fn 4b05H (set execution state)
          Process Control Functions
          Program Startup & Exit
          DOS Functions