Int 33 Fn 256C  - Logitech Mouse - Set Parameters - Set Mouse Port (seria  [M]

   AX = 256Ch
   BX = 0003h
   CX = port (1, 2)

Return: AX = FFFFh if driver installed for serial mouse

See Also: AX=246Ch,AX=256Ch/BX=0000h,AX=256Ch/BX=0004h,AX=276Ch