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...
d:\path\filename.ext 0 
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)
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DOS Fn 4b03H: Load Overlay