Int 21 Fn 4B05  - DOS 5+ - Set Execution State                             [D]

   AX = 4B05h
   DS:DX -> execution state structure (see below)

Return: CF clear if successful
       AX = 0000h
   CF set on error
       AX = error code (see AH=59h)

Note:  used by programs which intercept AX=4B00h to prepare new programs for
     execution (including setting the DOS version number).  No DOS, BIOS
     or other software interrupt may be called after return from this call
     before commencement of the child process.  If DOS is running in the
     HMA, A20 is turned off on return from this call.

See Also: AH=4Bh

Format of execution state structure:
Offset Size    Description
 00h   WORD    reserved (00h)
 02h   WORD    type flags
       bit 0: program is an .EXE
       bit 1: program is an overlay
 04h   DWORD   pointer to ASCIZ name of program file
 08h   WORD    PSP segment of new program
 0Ah   DWORD   starting CS:IP of new program
 0Eh   DWORD   program size including PSP