Int 15 Fn 5301  - Advanced Power Management V1.0+ - Connect Real-mode Int  [p]

   AX = 5301h
   BX = device ID of system BIOS (0000h)

Return: CF clear if successful
   CF set on error
       AH = error code (02h,05h,07h,09h) (see #0399)

Note:  on connection, an APM v1.1 or v1.2 BIOS switches to APM v1.0
     compatibility mode until it is informed that the user supports a
     newer version of APM (see AX=530Eh)

See Also: AX=5302h,AX=5303h,AX=5304h