||These are 16550 Universal Asynchronous Receiver Transmitter (UART) high-speed serial ports. Serial ports send and receive data one bit at a time. Serial devices such as a serial mouse, serial printers and modems may be connected to these ports. You may set the ports to be COM1, COM2, COM3, COM4 or Disabled with the BIOS Setup program. Ensure that both serial ports are not set to use the same COM port or interrupt (COM1 and COM3 both use interrupt 4; COM2 and COM4 both use interrupt 3).
Note: If the mouse has a mini-DIN (PS/2-style) connector, the Mouse Port must be used.