PORT

A computer port is a connection point or interface between a computer and an external or internal device. Internal ports may connect such devices as hard drives and CD ROM or DVD drives; external ports may connect modems, printers, mice and other devices.
                                                 TYPES OF PORTS

Computer ports have numerous functions and connectors of varying designs. Types of computer ports include:

• Serial Ports: These are most commonly used for connections to mice and modems.
• Parallel Ports:These are most commonly used for printers.
• Small Computer System Interface (SCSI) Ports: These are used to connect printers and up to seven total devices, such as hard disks and tape drives, to the same port; they can support higher data transmission speeds than serial or parallel ports.
• Universal Serial Bus (USB) Ports: As the name implies, these can be used to connect many devices including all previously mentioned plus keyboards, scanners, external hard drives, USB drives (also sometimes called thumb drives or portable USB drives), cameras, iphones and many other peripherals and devices.

Typical serial ports may use a serial RS-232C or an RS-232 connector. A parallel port on a personal computer (PC) may use a Centronics interface with a 25-pin connector.

SCSI ports come in a variety of interface connections; these include:

• Parallel SCSI (SPI): This port uses a parallel electrical bus configuration.
• Serial Attached SCSI (SAS): This port uses a serial design with SCSI technology.
• Internet Small Computer System Interface (iSCSI): This port is not a physical connection at all, but uses TCP/IP to facilitate data transfer over intranets, local area networks (LANs), wide area networks (WANs) or the Internet.

There are also many other interfaces that do not conform to the SCSI standard but use the SCSI command protocol.

USB ports are one of the most common computer ports in use today. They are hot pluggable external connectors with 4 pins (1 for power supply, 2 for data and 1 for a ground connection), measure 4.5 mm by 11.5 mm and come with a maximum length cable of 5 meters. The maximum number of devices that can be connected to a single computer with USB computer ports is 127.