Computer port (hardware) - AbsoluteAstronomy.com

Computer hardware

Personal computer hardware are component devices which are typically installed into or peripheral to a computer case to create a personal computer upon which system software is installed including a firmware interface such as a BIOS and an operating system which supports application software that...

, a port serves as an interface between the computer and other computers or peripheral devices. Physically, a port is a specialized outlet on a piece of equipment to which a plug

Electrical connector

An electrical connector is an electro-mechanical device for joining electrical circuits as an interface using a mechanical assembly. The connection may be temporary, as for portable equipment, require a tool for assembly and removal, or serve as a permanent electrical joint between two wires or...

or cable

Cable

A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...

connects. Electronically, the several conductors making up the outlet provide a signal transfer between devices.

The term "port" is derived from a Latin word "porta" (gate, entrance, door).

Physical shape

Hardware ports may be physically male or female

Gender of connectors and fasteners

In electrical and mechanical trades and manufacturing, each half of a pair of mating connectors or fasteners is conventionally assigned the designation male or female...

, but female ports are much more common.

Computer ports in common use cover a wide variety of shapes such as round (PS/2

PS/2 connector

The PS/2 connector is a 6-pin Mini-DIN connector used for connecting some keyboards and mice to a PC compatible computer system. Its name comes from the IBM Personal System/2 series of personal computers, with which it was introduced in 1987...

, etc.), rectangular (FireWire, etc.), square (Telephone plug

Telephone plug

A telephone plug is a type of male connector used to connect a telephone to the telephone wiring in a home or business, and in turn to a local telephone network. It is inserted into its female counterpart, a telephone "jack", commonly affixed to a wall or baseboard...

), trapezoidal (D-Sub

D-subminiature

The D-subminiature or D-sub is a common type of electrical connector. They are named for their characteristic D-shaped metal shield. When they were introduced, D-subs were among the smaller connectors used on computer systems....

— the old printer port was a DB-25), etc. There is some standardization to physical properties and function. For instance, most computers have a keyboard

Keyboard (computing)

In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...

port (currently a round DIN

DIN connector

A DIN connector is a connector that was originally standardized by the , the German national standards organization. There are DIN standards for a large number of different connectors, therefore the term "DIN connector" alone does not unambiguously identify any particular type of connector unless...

-like outlet referred to as PS/2), into which the keyboard is connected.

Electrical signal transfer

Electronically, hardware ports can almost always be divided into two groups based on the signal transfer:

Serial port
Serial port
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...

s send and receive one bit at a time via a single wire pair (Ground and +/-).
Parallel port
Parallel port
A parallel port is a type of interface found on computers for connecting various peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Centronics port...

s send multiple bits at the same time over several sets of wires.

After ports are connected, they typically require handshaking

Handshaking

In information technology, telecommunications, and related fields, handshaking is an automated process of negotiation that dynamically sets parameters of a communications channel established between two entities before normal communication over the channel begins...

, where transfer type, transfer rate, and other necessary information is shared before data are sent.

Hot-swappable ports can be connected while equipment is running. Almost all ports on personal computers are hot-swappable.

Plug-and-play

Plug-and-play

In computing, plug and play is a term used to describe the characteristic of a computer bus, or device specification, which facilitates the discovery of a hardware component in a system, without the need for physical device configuration, or user intervention in resolving resource conflicts.Plug...

ports are designed so that the connected devices automatically start handshaking as soon as the hot-swapping is done. USB

Universal Serial Bus

USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

ports and FireWire ports are plug-and-play.

Auto-detect or auto-detection ports are usually plug-and-play, but they offer another type of convenience. An auto-detect port may automatically determine what kind of device has been attached, but it also determines what purpose the port itself should have. For example, some sound card

Sound card

A sound card is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware...

s allow plugging in several different types of audio speakers

Computer speaker

Computer speakers, or multimedia speakers, are speakers external to a computer, that disable the lower fidelity built-in speaker. They often have a low-power internal amplifier. The standard audio connection is a 3.5 mm stereo jack plug often color-coded lime green for computer sound cards...

; then a dialogue box pops up on the computer screen asking whether the speaker is left, right, front, or rear for surround sound

Surround sound

Surround sound encompasses a range of techniques such as for enriching the sound reproduction quality of an audio source with audio channels reproduced via additional, discrete speakers. Surround sound is characterized by a listener location or sweet spot where the audio effects work best, and...

installations. The user's response determines the purpose of the port, which is physically a 1/8" tip-ring-sleeve (TRS connector

TRS connector

A TRS connector is a common family of connector typically used for analog signals including audio. It is cylindrical in shape, typically with three contacts, although sometimes with two or four . It is also called an audio jack, phone jack, phone plug, and jack plug...

) minijack. Some auto-detect ports can even switch between input and output based on context.

As of 2006, manufacturers have nearly standardized colors associated with ports on personal computers, although there are no guarantees. The following is a short list:

Orange, purple, or grey: Keyboard PS/2
Green: Mouse PS/2
Blue or magenta: Parallel printer DB-25
Amber: Serial DB-25 or DB-9
Pastel pink: Microphone 1/8" stereo (TRS) minijack
Pastel green: Speaker 1/8" stereo (TRS) minijack

FireWire ports used with video equipment (among other devices) can be either 4-pin or 6-pin. The two extra conductors in the 6-pin connection carry electrical power. This is why a self-powered device such as a camcorder often connects with a cable that is 4-pins on the camera side and 6-pins on the computer side, the two power conductors simply being ignored. This is also why laptop computers usually have only 4-pin FireWire ports, as they cannot provide enough power to meet requirements for devices needing the power provided by 6-pin connections.

Optical (light) fiber, microwave, and other technologies (i.e., quantum) have different kinds of connections, as metal wires are not effective for signal transfers with these technologies. Optical connections are usually a polished glass or plastic interface, possibly with an oil that lessens refraction between the two interface surfaces. Microwaves are conducted through a pipe, which can be seen on a large scale by examining microwave towers with "funnels" on them leading to pipes.

Hardware port trunking (HPT) is a technology that allows multiple hardware ports to be combined into a single group, effectively creating a single connection with a higher bandwidth

Bandwidth (computing)

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...

, sometimes referred to as a double-barrel approach. This technology also provides a higher degree of fault tolerance because a failure on one port may just mean a slow-down rather than a dropout. By contrast, in Software Port Trunking (SPT), two agents (websites, channels, etc.) are bonded into one with the same effectiveness; i.e., ISDN

Integrated Services Digital Network

Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...

B1 (64K) plus B2 (64K) equals data throughput of 128K.

External links

Tom's Hardware PC Interfaces 101, a quick overview of commonly used ports for PCs.
TVicHW32, Direct Port I/O from Win32.
Interface Ports I/O form PC

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Physical shape

Electrical signal transfer

See also

External links