Int D4 Fn 10  - Pc-mos/386 V3.0+ - Enter/leave Native 386 Execution Mode   [O]

   AH = 10h
   AL = direction (00h return to V86 mode, 01h enter native mode)
   CX = length in bytes of Native Context Area ( >=1024 )
   DX = segment of Native Context Area

Return: CF clear if successful
       running in desired mode at instruction following INT D4 call
       all segment registers converted to appropriate selectors/segments
   CF set on error
       AX = error code (see #1366 at INT 21/AH=59h/BX=0000h)

Note:  MS-DOS calls are available in protected mode

See Also: AH=11h,AH=12h,AH=13h,INT 2F/AX=1687h,INT 67/AX=DE0Ch,INT 38