Ports

A port is an external connecting socket on the outside the computer. This is a pathway into and out of the computer. A port lets users plug in outside peripherals, such as monitors, scanners and printers.

Serial Ports

Serial ports are external I/O connectors used to attach modems, scanners or other serial interface devices to the computer. The typical serial ports use a 9-pin DB-9 or a 25-pin DB-25 connector. Serial ports transmit bits one after another on a single communications line. Serial lines frequently are used to link equipment that is not located close by.

Parallel Ports

Parallel ports are external I/O connectors on a computer used to hook up printers or other parallel interface devices. The parallel port uses a DB-25 connector. This port transmits several bits simultaneously. Parallel lines move information faster than serial lines do.

DB-9/DB-25: Plugs and sockets (connectors) with 9 and 25 pins respectively. These connectors are commonly used for RS-232 interfaces. The same DB-25 connector used in RS-232 serial cables is also used as a connector for parallel printer cables.

RS-232: This is a 25-wire electrical interface between a computer and a peripheral device. This is an EIA standard for serial transmission that uses a DB-25 or DB-9 connector.