Hardware components of the PC
External PC connection ports
Serial port (COM 1)

The serial port is a standard input/ output interface that supports serial communication. A computer system may have two serial ports as standard. A modem or other serial terminal device connects to this port and information is processed relatively slowly one bit at a time up to 115.2KB per second. The appearance of a serial port can be described as a male 9-pin D-type connector, although a 25-pin version was commonly available before the introduction of the USB port.