COMPUTER PORTS
The input/output device is a piece of hardware that can be used for both providing data to a computer and for receiving information from it. There are input/output interfaces called ports.
A computer port is a connecting socket, outside the system into which different types of cables are plugged. I/O ports are the interfaces through which computers communicate with external devices such as printers, modems, joysticks and terminals. Physically, they are distinguished by their external shape, numbers and shape of contact pins/points. Different interfaces and ports have different communication speeds and bandwidths to carry data to and from the CPU. Some such commonly used ports are explained below.
Parallel Port: A parallel port transmits 8 bits of a byte of data in parallel as it contains eight or more data lines for control of I/O devices. It is commonly used to connect the printer to a computer. It is used for transmitting fast data over short distances because interference among multiple signals limits the cable to relatively short distances.
Serial Port: A serial port transmits one bit of a byte at a time as a single stream of bits. It is meant for transmitting slow data over long distances. Communication over a phone system is an example of serial communication. A serial port connects a variety of devices such as modems, scanners, barcode readers and device control circuits.
PS/2 Port: It is one of the serial port connectors used to plug mouse and keyboards into a personal computer. It consists of six pins in a small and round shaped socket.
Universal Serial Bus (USB) Port: USB port is the most popular port used to connect up to 127 peripheral devices such as digital camera, speaker, scanner, printer, plotter, modem, joystick, pen drive, etc. USB permits Plug and Play – i.e. it allows us to install device drivers as and when the devices are plugged on.
Small Computer System Interface (SCSI) Port: SCSI port allows data transmission in a “daisy chain” to up to 7 devices at a speed (32 bits at a time) much higher than serial and parallel ports. The devices that may be connected to SCSI ports are hard-disk drives, CD-ROM drives, scanners, backup units, network adapters etc. In daisy chain several devices are connected in series. If data has to reach the seventh device then it needs to go through, all the six devices first.
Fire Wire (IEEE 1394) Port: Fire Wire port is a relatively a new technology for high speed data communication. The need of this arose due to large audio and video data movement from multimedia devices. The devices connected via Fire Wire Port are Video Camera, External Hard Disk Drives, External CD/DVD Drives. Microsoft has developed device drivers to support IEEE1394 in all the versions after Windows 95. Linux also supports this port. It is extremely fast with Data Transfer Rate up to 400 Mb/sec.
