Serial
port Serial port is COM interface . This is the most ancient old mouse interface is a 9-pin or 25-pin D-type interface, you can use the mouse to the serial port on the host computer. The advantage is that it has the most scope of application and models, from ancient computers without PS / 2 interface and USB interface to the latest computers.
The disadvantage is that the data transmission rate of serial communication is too low, and high-end and high-end mice can not take advantage of its high performance