Types of Computer Ports and Their Functions:-
What is the meaning of computer port-
The main function of a computer port is to act as a link to the connection, where wires can be plugged from peripherals and allow data to flow from one device to another device.
A computer port is also called as a Communication Port as it is responsible for communication between the computer and its peripheral device. Generally, the female end of the connector is referred to as a port and it usually sits on the motherboard.
In Computers, communication ports can be divided into two types based on the type or protocol used for communication.
What are the main types of computer ports-
There are mainly two types of computer ports which are given below-
- Serial Ports .
- Parallel Ports.
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Serial Ports –
A serial port is an interface through which peripherals can be connected using a serial protocol which involves the transmission of data one bit at a time over a single communication line. The most common type of serial port is a D-Subminiature or a D-sub connector that carry RS-232 signals.
Parallel Ports –
A parallel port, on the other hand, is an interface through which the communication between a computer and its peripheral device is in a parallel manner i.e. data is transferred in or out in parallel using more than one communication line or wire. Printer port is an example of parallel port.
The various ports of the computer are described below-
The PS / 2 connector port is developed by IBM for mouse and keyboard connection. It was introduced with IBM’s Personal Systems / 2 Series computers and hence the name PS / 2 connecting port. The PS / 2 connector ports are painted purple for the keyboard and green for the mouse.
PS / 2 is a 6-pin DIN connector Pin out port of a PS / 2 female connector. The figure shows 6 below-
The PS / 2 port is now considered an additional port because USB ports are more modern than it is now and it is rarely found as a legacy port on modern motherboards.
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Serial Port –
Even though the communication in PS/2 and USB is serial, technically, the term Serial Port is used to refer the interface that is compliant to RS-232 standard. There are two types of serial ports that are commonly found on a computer: DB-25 and DE-9.
DB-25 is a variant of D-sub connector and is the original port for RS-232 serial communication. They were developed as the main port for serial connections using RS-232 protocol but most of the applications did not require all the pins.
Hence, DE-9 was developed for RS-232 based serial communication while DB-25 was rarely used as a serial port and often used as a parallel printer port as a replacement of the Centronics Parallel 36 pin connector.
DE-9 or RS-232 or Com Port:-
DE-9 is the main port for RS-232 serial communication. It is a D-sub connector with E shell and is often miscalled as DB-9. A DE-9 port is also called as a COM port and allows full duplex serial communication between the computer and it’s peripheral.
Some of the applications of DE-9 port are serial interface with mouse, keyboard, modem, uninterruptible power supplies (UPS) and other external RS-232 compatible devices.
The pinout diagram of DE-9 port is shown below-
The use of DB-25 and DE-9 ports for communication is in decline and are replaced by USBs or other ports.
Parallel port or Centronics 36 pin port:-
Parallel ports are an interface between computers and peripheral devices such as printer devices for parallel communication. The Centronics port is a 36-pin port that was created as an interface for printers and scanners, and so a parallel port is also called a Centronics port.
Before the widespread use of USB ports, parallel ports were very common in printers. The Centronics port was later replaced by the DB-25 port with a parallel interface.
Audio port –
Audio ports are used to connect speakers or other audio output devices to a computer. Audio signals can be either analog or digital, depending on the port and its corresponding connector.
Surround Sound Connector or 3.5mm TRS Connector Audio Port It is most commonly found that can be used to connect stereo headphones or surround sound channels. In addition to audio out, most computers have a 6 connective system for microphone connection.
The 6 connectors are painted as blue, lime, pink, orange, black and gray. These 6 connectors can be used for up to 6 channels for an ambient sound configuration.
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S/PDIF / TOSLINK Port:-
The Sony/Phillips Digital Interface Format (S/PDIF) is an audio interconnect used in home media. It supports digital audio and can be transmitted using a coaxial RCA Audio cable or an optical fiber TOSLINK connector.
Most computers home entertainment systems are equipped with S/PDIF over TOSLINK. TOSLINK (Toshiba Link) is most frequently used digital audio port that can support 7.1 channel surround sound with just one cable. In the following image, the port on the right is an S/PDIF port.
Video port / VGA port:-
VGA ports are available on many computers, projectors, video cards and high definition TVs. It is a D-sub connector with 15 pins in 3 rows. The connector is called DE-15.
The VGA port is the main interface between computers and older CRT monitors. Even modern LCD and LED monitors have VGA ports, but the picture quality is declining. VGA carries analog video signals up to 648X480 resolution.
With the increase in use of digital video, VGA ports are gradually being replaced by HDMI and Display Ports. Some laptops are equipped with on-board VGA ports in order to connect to external monitors or projectors. The pinout of a VGA port is shown below.
Digital Video Interface (DVI) –
DVI is a high speed digital interface between a display controller like a computer and a display device like a monitor. It was developed with an aim of transmitting lossless digital video signals and replace the analogue VGA technology.
There are three types of DVI connectors based on the signals it can carry: DVI-I, DVI-D and DVI-A. DVI-I is a DVI port with integrated analogue and digital signals. DVI-D supports only digital signals and DVI-A supports only analogue signals.
The digital signals can be either single link or dual link where a single link supports a digital signal up to 1920X1080 resolution and a dual link supports a digital signal up to 2560X1600 resolution. The following image compares the structures of DVI-I, DVI-D and DVI-A types along with the pinouts.
Mini-DVI port is developed by Apple as an alternative to Mini-VGA port and is physically similar to one. It is smaller than a regular DVI port.
It is a 32 pin port and is capable of transmitting DVI, composite, S-Video and VGA signals with respective adapters. The following image shows a Mini-DVI port and its compatible cable.
Micro-DVI port, as the name suggests is physically smaller than Mini-DVI and is capable of transmitting only digital signals.
This port can be connected to external devices with DVI and VGA interfaces and respective adapters are required. In the following image, a Micro-DVI port can be seen adjacent to headphone and USB ports.
Display Port –
Display Port is a digital display interface with optional multiple channel audio and other forms of data. Display Port is developed with an aim of replacing VGA and DVI ports as the main interface between a computer and monitor.
The latest version DisplayPort 1.3 can handle a resolution up to 7680 X 4320.
The Display Port has a 20 pin connector, which is a very less number when compared to DVI port and offers better resolution. The pin out diagram of a Display Port is shown below.
Update: DisplayPort 1.4a is the latest (in production) version of DisplayPort Specification with support for 4K (3840 x 2160) at 120 Hz or 8K (7680 x 4320) at 60 Hz. An improved DisplayPort version 2.0 specification is released in June of 2019 with an increased bandwidth of 77.37 Gbps (approximately).
Mini DisplayPort –
Apple introduced a miniature version of DisplayPort and called it Mini DisplayPort (mDP or Mini DP). Even though Mini DisplayPort has 20 pins, the physical size of the connector is smaller than a regular DisplayPort and the pin out is also different.
Most laptops provide Mini DisplayPort as an additional video out option in addition to HDMI.
RCA Connector –
RCA Connector can carry composite video and stereo audio signals over three cables. Composite video transmits analogue video signals and the connector is as yellow colored RCA connector.
The video signals are transmitted over a single channel along with the line and frame synchronization pulses at a maximum resolution of 576i (standard resolution).
The red and white connectors are used for stereo audio signals (red for right channel and white for left channel).
Component Video –
Component Video is an interface where the video signals are split into more than two channels and the quality of the video signal is better that Composite video.
Like composite video, component video transmits only video signals and two separate connectors must be used for stereo audio. Component video port can transmit both analogue and digital video signals.
The ports of the commonly found Component video uses 3 connectors and are color coded as Green, Blue and Red.
S-Video or Separate Video connector is used for transmitting only video signals. The picture quality is better than that of Composite video but has a lesser resolution than Component video.
The S-Video port is generally black in color and is present on all TVs and most computers. S-Video port looks like a PS/2 port but consists of only 4 pins.
Out of the 4 pins, one pin is used to carry the intensity signals (black and white) and other pin is used to carry color signals. Both these pins have their respective ground pins. The pinout diagram of an S-Video port is shown below.
HDMI is an abbreviation of High Definition Media Interface. HDMI is a digital interface to connect High Definition and Ultra High Definition devices like Computer monitors, HDTVs, Blu-Ray players, gaming consoles, High Definition Cameras etc.
HDMI can be used to carry uncompressed video and compressed or uncompressed audio signals. The HDMI port of type A is shown below.
The HDMI connector consists of 19 pins and the latest version of HDMI i.e. HDMI 2.0 can carry digital video signal up to a resolution of 4096×2160 and 32 audio channels. The pinout diagram of an HDMI port is as follows.
Update: The latest version of HDMI is 2.1 with much improved bandwidth, resolution and support from video card manufacturers. While HDMI 2.0 has a data bandwidth of 18 Gbps, the HDMI 2.1 has a staggering 48 Gbps of bandwidth. Coming to the display resolution, HDMI 2.1 supports 4K and 8K at 120 Hz refresh rate. Most modern (at least high end) graphics cards like Nvidia RTX 3090 provide at least a couple of HDMI 2.1 Ports to connect with monitors and TVs.
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Mini HDMI / Micro HDMI:-
With HDMI 1.3 Version, a new HDMI Port and Connector combination is released called the Mini HDMI. Physically, it is smaller than a regular HDMI Port but has same 19 Pin. Intended for portable devices like laptops, cameras, camcorders, the Mini HDMI Port isn’t that popular.
HDMI developers introduced a new HDMI Connector and Port called Micro HDMI with HDMI Version 1.4. Micro HDMI also has 19 pins (just like regular HDMI and Mini HDMI) but the pinout is different.
Micro HDMI is often used in cameras, single board computers (like Raspberry Pi 4), etc. where physically it is difficult to include a regular HDMI port.
The size of Micro HDMI is significantly smaller than regular HDMI and has some resemblance to a micro–USB Port (sometimes people confuse among the two). The port on the left is a micro USB port and the one on the right is a micro HDMI Port.
Universal Serial Bus (USB) replaced serial ports, parallel ports, PS/2 connectors, game ports and power chargers for portable devices.
USB port can be used to transfer data, act as an interface for peripherals and even act as power supply for devices connected to it. There are three kinds of USB ports: Type A, Type B or mini USB and Micro USB.
USB Type A-
USB Type-A port is a 4 pin connector. There are different versions of Type – A USB ports: USB 1.1, USB 2.0 and USB 3.0. USB 3.0 is the common standard and supports a data rate of 400MBps.
USB 3.1 is also released and supports a data rate up to 10Gbps. Usually, but not all the times, the USB 2.0 is Black color coded and USB 3.0 is Blue. The following image shows USB 2.0 and USB 3.0 ports.
The pinout diagram of USB Type – A port is shown below. The pinout is common to all standards of Type – A.