COMPUTER HARDWARE PORTS




COMPUTER PORTS

In computer hardware, 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 or cable connects.

Hardware ports may be physically male or female, but female ports are much more common.

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

Serial ports send and receive one bit at a time via a single wire pair (Ground and +/-).

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

After ports are connected, they typically require handshaking, 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. About the only port on personal computers that is not hot-swappable is the keyboard PS/2 connector. Hot swapping a keyboard on many computer models can cause permanent damage to the motherboard.

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

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:
Main article: PC System Design Guide

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.

Ethernet
Ethernet is a family of computer networking technologies for local area networks (LANs) commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies.

IEEE 1394 interface
costs and a simplified, more adaptable The IEEE 1394 interface is a serial bus interface standard for high-speed communications and isochronous real-time data transfer, frequently used by personal computers, as well as in digital audio, digital video, automotive, and aeronautics applications. The interface is also known by the brand names of FireWire (Apple), i.LINK (Sony), and Lynx (Texas Instruments). IEEE 1394 replaced parallel SCSI in many applications, because of lower implementationcabling system. The 1394 standard also defines a backplane interface, though this is not as widely used.

Parallel
A parallel port is a type of interface found on computers (personal and otherwise) 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. The IEEE 1284 standard defines the bi-directional version of the port, which allows the transmission and reception of data bits at the same time.

PS/2
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. The PS/2 mouse connector generally replaced the older DE-9 RS-232 “serial mouse” connector, while the PS/2 keyboard connector replaced the larger 5-pin/180° DIN connector used in the IBM PC/AT design. The PS/2 designs on keyboard and mouse interfaces are electrically similar and employ the same communication protocol. However, a given system’s keyboard and mouse port may not be interchangeable since the two devices use a different set of commands. Today this connector has all but been replaced by USB

Serial
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time (contrast parallel port). Throughout most of the history of personal computers, data transfer through serial ports connected the computer to devices such as terminals and various peripherals.

While such interfaces as Ethernet, FireWire, and USB all send data as a serial stream, the term “serial port” usually identifies hardware more or less compliant to the RS-232 standard, intended to interface with a modem or with a similar communication device.

Modern computers without serial ports may require serial-to-USB converters to allow compatibility with RS 232 serial devices. Serial ports are still used in applications such as industrial automation systems, scientific instruments, shop till systems and some industrial and consumer products. Server computers may use a serial port as a control console for diagnostics. Network equipment (such as routers and switches) often use serial console for configuration. Serial ports are still used in these areas as they are simple, cheap and their console functions are highly standardized and widespread. A serial port requires very little supporting software from the host system.

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

USB was designed to standardize the connection of computer peripherals, such as keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters to personal computers, both to communicate and to supply electric power. It has become commonplace on other devices, such as smartphones, PDAs and video game consoles. USB has effectively replaced a variety of earlier interfaces, such as serial and parallel ports, as well as separate power chargers for portable devices.

VGA
A Video Graphics Array (VGA) connector is a three-row 15-pin DE-15 connector. The 15-pin VGA connector is found on many video cards, computer monitors, and some high definition television sets. On laptop computers or other small devices, a mini-VGA port is sometimes used in place of the full-sized VGA connector.

DE-15 is also conventionally called RGB connector, D-sub 15, mini sub D15, mini D15, DB-15, HDB-15, HD-15 or HD15 (High Density, to distinguish it from the older and less flexible DE-9 connector used on older VGA cards, which has the same shell size but only two rows of pins).

VGA connectors and cables carry analog component RGBHV (red, green, blue, horizontal sync, vertical sync) video signals, and VESA Display Data Channel (VESA DDC) data. In the original version of DE-15 pinout, one pin was keyed and 4 pins carried Monitor ID bits which were rarely used; VESA DDC redefined some of these pins and replaced the key pin with +5 V DC power supply.

 

Digital Visual Interface
The Digital–visual interface (DVI) is a video interface standard covering the transmission of video between a source device (such as a personal computer) and a display device. The DVI standard has achieved widespread acceptance in the PC industry, both in desktop PCs and monitors. Most contemporary retail desktop PCs and LCD monitors feature a DVI interface, and many other devices (such as projectors and consumer televisions) support DVI indirectly through HDMI, another video interface standard. Most laptops still have legacy VGA and, in some models, HDMI ports, but fewer have DVI.

SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it can connect a wide range of other devices, including scanners and CD drives. The SCSI standard defines command sets for specific peripheral device types; the presence of “unknown” as one of these types means that in theory it can be used as an interface to almost any device, but the standard is highly pragmatic and addressed toward commercial requirements.

SCSI is an intelligent, peripheral, buffered, peer to peer interface. It hides the complexity of physical format. Every device attaches to the SCSI bus in a similar manner. Up to 8 or 16 devices can be attached to a single bus.

TRS
A TRS connector (tip, ring, sleeve) 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 (a TS connector) or four (a TRRS connector). It is also called an audio jack, phone jack, phone plug, jack plug. Specific models are known as stereo plug, mini-jack, mini-stereo, headphone jack, tiny telephone connector and Bantum plug

The TRS connector was invented for use in telephone switchboards in the 20th century and is still widely used, both in its original ¼″ (exactly 6.35 mm) size and in miniaturized versions: 3.5 mm (approx. ⅛″) and 2.5 mm (approx. 3/32″). The connector’s name is an initialism derived from the names of three conducting parts of the plug: Tip, Ring, and Sleeve – hence, TRS.

 

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