Int 33 Fn 256C  - Logitech Mouse - Set Parameters - Set Emulation (serial  [M]

   AX = 256Ch
   BX = 0001h
   CX = emulation
       00h 5 byte packed binary
       01h 3 byte packed binary
       02h hexadecimal
       03h relative bit pad
       04h not supported
       05h MM Series
       06h not supported
       07h Microsoft

Return: AX = FFFFh if driver installed for serial mouse

See Also: AX=246Ch,AX=256Ch/BX=0000h,AX=256Ch/BX=0003h,AX=276Ch