Computer Peripheral Devices

What is Computer Peripheral Device?

A computer peripheral device, also called I/O device, refers to the auxiliary device connected internally or externally but directly to a computer. These devices offer additional functions and put information into and get it out from a computer.

In simple words, a computer peripheral device is not a core device of the computer and does not contribute directly to the primary function of the computer but simply helps the end users to access and use its functionalities.

Understanding Computer Peripheral Devices

Understanding Computer Peripheral Devices

Ideally, computer peripherals are devices that are connected to the computer to transfer data to or from it.

Though most of the computer peripherals are connected externally, there are a few that are connected internally as well.

Different connection types are usually used for this.

Computer peripheral device and components of a computer or computer hardware are terms that are often used interchangeably by people ignorant about the differences between them.

Therefore, it is important at this point to know the differences between them and then know about the different types of computer peripherals.

In simple words, a peripheral device is not the core device of a computer.

This means that a computer may perform without a few specific peripheral devices connected to it.

These devices typically add functionality to the data input and output by performing some additional functions.

And, technically speaking, computer hardware signifies those physical parts that make up a computer.

These are enough for a computer to work. The computer peripherals are also pieces of hardware but are additional ones that help the computer to work more efficiently.

Here are a few major differences that you should know about computer hardware and peripherals.

Computer hardware can take input, display output, execute commands and store data.

On the other hand, computer peripherals typically help in putting information into the computer and get information out of it.

The features of hardware include efficiency, functionality, portability, user documentation, and others.

On the other hand, features of peripherals include storage, usability, speed, and others.

While hardware is intended to give instructions to software, the computer peripherals are intended to give instructions to the computer.

The computer peripherals are typically connected to the core system of the computer through the motherboard.

As said earlier, there are different connection types and protocols followed for that. Each connection comes with a different plug, cable, and protocol type.

Some of the most commonly used computer peripheral connection types are:

Now, computer peripheral devices can be of different types and can be categorized according to the data transmission direction and their connection type.

However, these devices are usually categorized based on whether they are connected internally or externally.

The internal peripheral devices of a computer are found inside the computer case.

A few examples of internal peripheral devices of a computer are:

Nowadays, all of these are not used though.

On the other hand, the peripheral devices that are located outside the computer chassis or case are called external peripheral devices. A few examples of these devices are:

The categorization of the computer peripheral devices can also be made on the basis of their data communication or transmission direction.

There are three broad categories in which the peripheral devices can be segregated into such as:

The input peripheral devices are those that are used to feed in data into the computer system.

These devices take in inputs, digitize them, and forward it to the motherboard for processing.

The list of input peripheral devices of a computer includes:

On the other hand, the output peripheral devices of a computer are those that display the processed data or information.

The output can be in any format such as picture, video, or sound. The examples of output peripheral devices are:

And finally, the composite peripheral devices are usually used to pass on data and also act as a transitional hop such as:

Though the lists are long and confusing to a newbie, there is no reason to believe that everything that is connected to a computer system is a peripheral device. Now, take a look that are not but are often mistaken as one.

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What is Not a Peripheral Device?

The most significant part of a computer is the CPU or the Central Processing Unit, which is not a peripheral device.

The main reason for excluding this component of a computer from the list of peripheral devices is that a computer simply cannot function without a CPU or its ‘brain.’

Then, the motherboard, which is also called the main board sometimes, is not a computer peripheral device.

The primary reason for it is that all other core components of a computer are typically connected to it and usually communicate through this board.

The memory of a computer is also not a peripheral device because it stores the data processed and several other useful command files are also stored inside the computer memory.

Therefore, without a memory the CPU cannot function, and, in turn, the computer will be useless.

Also, the main storage of the computer or the Hard Disk Drive is not considered to be a peripheral device.

The reason behind it is that the processed data is stored inside this drive typically for long term usage.

Types of Peripheral Devices

Now, it is time to look into the different peripherals of the computer in detail.

Blank Media and Mass Storage:

These refer to the CD or DVD disc. CD or a Compact Disc is a flat, round disc used to store data.

It is read by a CD-ROM drive that typically comes with a laser.

Any regular CD can store up to 650 MB of data which is equivalent to storing 72 minutes of music.

There are also a few specific CDs that can hold up to 700 MB of data or up to 80 minutes of music approximately.

DVD or Digital Video Disc or Digital Versatile Disc is also a circular disc that is read by a DVD-ROM.

Usually, the DVDs are of the same size of any regular CDs in terms of data holding capacity.


It is needless to say that the battery supplies power to the computer, especially a laptop computer so that it can run without being connected to an electrical outlet with a power cord and a plug.

The desktop computers also come with a coin-cell battery that is less powerful than those that are found in a laptop computer.

This battery typically supplies power to the real-time clock of the computer and the CMOS memory.

Computer Cases or Chassis:

This is the cabinet or the housing of the computer that holds all the components of it in one place in an organized manner and also protects them from damage.

These are also referred to as the form factor. Usually, the computer cases come in a vertical tower form and can be divided into mini-tower, mid-tower, or full-tower cases.

The computer cases are usually built from metal sheets where the real panel has slots to accommodate the connectors for different peripherals that typically protrude from the motherboard.

Depending on the model and design, these cases may have some or all of the following list of components that include expansion slots, power button, reset button, LEDs to indicate power, network and hard drive activity, I/O ports for headphone and even a few USB ports on the front panel.

These cases also come with vents to allow air passage and typically hold the motherboard, Power Supply Unit, drive bays and wires that connect switches, indicators and other elements to the motherboard.

CD-ROM or DVD-RW Drives:

The CD-ROM drives read the CDs. These are the CD-Players actually and are located inside the computer. It can read audio signals as well as other computer data.

DVD-RW Drive is also much similar to the CD-players in the computer. These drives can read or read and write DVDs. There are also DVD-ROMs that can only read DVDs but cannot write it.

Memory Stick:

A memory stick is more commonly referred to as a USB flash drive. This is a portable and a small device which is not longer than the index finger, if not the little.

These devices typically fit onto a USB port and are used to transfer and store files in them.

These flash drives come with varied data holding capacity such as 512 MB, 1 GB, or even more.


The keyboard is one of the most important input devices used on a computer.

These computer keyboards are pretty much the same as the keyboards of an electric typewriter but it comes with a few additional keys.

The number of keys and design may vary according to the make and model.

However, the letter and number keys remain the same in number as well as in location but there may be a slight difference in the placements or inclusions of a few additional function keys.

According to the US norm, a typical modern keyboard comes with 104 keys while there are 105 keys in its layout according to the conventions of the rest of the world.

A desktop keyboard is often called a full-size keyboard while the laptop keyboards are usually shorter in size with the numeric keypad on the right often left out.

Also, keyboards can be of different types such as flexible, handheld, thumb-sized and multifunctional.

These can also be of special use types that use non-conventional layout.

These can be chorded keyboard, software keyboard, projection keyboard, and optical keyboard.


A computer mouse is a handheld input device. It allows the users to control the mouse pointer, often called the cursor, in a GUI or a Graphical User Interface.

A user can perform different functions by using the mouse such as selecting a file or folder, opening a file or a program, and more without needing to memorize any command for it like it used to be in the old MS-DOS environment.

The mouse detects 2D motion relative to the surface on which it is being moved.

This motion is then converted into the motion of the pointer on the display which allows smoother control of the GUI of the computer.

There are two buttons in a computer mouse that performs different functions.

The left button is mainly used to point the cursor and the right button opens a menu with different functions such as cut, copy, paste, font, paragraphs, bullet, numbering, hyperlink and more.

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There is a scroll wheel in between the two buttons that allows moving a page up or down along with some added control and dimensional input.

There are few specific mice designed for specific uses but generally you will find a mechanical mouse, optical mouse, laser mouse, inertial and gyroscopic mouse, 3D mouse, tactical mouse, ergonomic mouse, gaming mouse and more.


Modems are hardware devices that are connected to the computer to send and receive signals over telephone lines.

A short for modulator/demodulator, a modem converts or modulates digital signal to analog signal while sending signals and transmits it through the telephone lines.

On the other hand, while receiving signals it demodulates or converts the analog signals back into digital signals.

A modem is an asynchronous device which means that the signals are transmitted by it as a discontinuous stream of small packets.

Computer modems can be of four different types and are usually categorized on the basis of their location.

An onboard modem is usually built onto the motherboard of the computer and cannot be removed. However, these can be disabled through BIOS setup or by using a jumper.

An internal computer modem is that which connects to a PCI slot in a newer model of desktop computer or to the ISA slot on an old computer.

The external computer modem is like a box that is connected to the computer from the outside by using a USB port or serial port.

And, removable computer modems are those that are used in older laptops via the PCMCIA slot. These modems can be added or removed according to need.


The monitor of a computer is an output device that displays images and videos.

It has a display screen and a hard shell to hold it along with some circuitry and power supply. The modern TFT-LCD or LED monitors have replaced the old CRT models.

These monitors are typically connected to the computer via different types of connector depending on the make and model that include VGA, HDMI, Digital Visual Interface or DVI, USB-C, Display Port, and LVDS or Low Voltage Differential Signaling or any other proprietary connectors.

Computer monitors can come in different sizes, aspect ratio, resolution and color gamut and other universal or professional features.

And, depending on the type of the computer, it may also have different mounting options such as VESA mount, fixed rack mount or stowable rack mount, panel mount or as an open frame.

Network Interface Card:

Network Interface Card, also commonly referred to as NIC or a network adapter or Local Area Network or LAN adapter, is actually a printed circuit board.

It contains all those necessary hardware elements that are used to connect one computer to another or to a network.

The main purpose of the network adapter is to allow both wired as well as wireless communications between the computers connected in a LAN. It also helps in communicating over a very large scale network via Internet Protocol.

Typically, the Network Interface Card is a physical layer as well as a data link layer tool that provides the required hardware circuitry to run the physical layer processes as well as a few data link layer processes on it.

The network adapters are of two types namely, internal and external network cards.

The internal networks cards are inserted into a slot on the motherboard and need network cables to allow network access.

These internal network cards can be further divided into two categories such as PCI or Peripheral Component Interconnect connection and the Industry Standard Architecture or ISA.

On the other hand, the external network cards are of two types – wireless and USB based.

The wireless network card is inserted into the motherboard and does not need any network cable to connect to the network since it can access wireless signals.

The USB network cards are inserted into a USB port to get connected to the motherboard.

Power Supply Unit:

The PSU or Power Supply Unit is an internal peripheral device of a computer that supplies power to components inside the computer.

In addition to that, it also converts AC from the standard wall sockets to lower DC voltage that is used by the computer.

Some power supplies may adapt to the voltage of the mains automatically while some may have a switch to select the input voltage manually.

The modern computers usually come with an SMPS or Switched Mode Power Supply and also comply with the ATX specs.

This includes the form factor as well as the voltage tolerance.

This means that the power supply provides a standby of 5 volts always when it is connected to the mains supply so that a few peripherals of the computer are powered along with a few standby functions.

The modern power supplies are usually turned off and on by a signal sent by the motherboard and also send a signal to notify the motherboard when the DC voltage is in spec.

This allows safe booting and power up of the computer.

The standby voltage supplied by the some advanced Power Supply Units can start a computer remotely through Wake-on-Ring or Wake-on-LAN or even locally by Keyboard Power ON or KBPO technology depending on the support provided by the motherboard.


This is an external hardware device that produces hard copies of the processed data. Printers are usually used to print text, images, and photos.

Typically, there are different types of printers that can be attached to a computer such as laser jet printers, inkjet printers,

Dot matrix printers, 3D printers, AIO or All-in-One printers, LED printers, MFP or Multifunction Printers, thermal printers, and plotters.

There are different types of printer interfaces as well that allow connecting them to the computer and communicating with it.

The most common type of interface is a USB cable for wired connectivity. However, there are some wireless printers that use Wi-Fi for connectivity.

There are also some other interfaces and cables used to connect a printer such as Cat 5, parallel port, Firewire, SCSI or Small Computer System Interface, Microbits Peripheral Products or MPP-1150, and serial port.

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This is another hardware input peripheral device. This allows converting an image or a text document into a digital file when it is placed on the glass pane and the light moves from one side to the other reading the document.

It sends the signals to the computer that reads as well as displays the scanned document.

Just like the printers, a scanner is also connected to the computer through one of the several interfaces such as Firewire port, parallel port, USB port or SCSI port.

Computer scanners can be of different types such as card scanner which can scan business cards, drum scanner that can scan quickly by rotating the page to be scanned around a drum, handheld scanner and pen scanner that scans the devices are dragged over the text, and sheet fed scanner where the paper is fed to the scanner.

The modern scanners however typically use a Contact Image Sensor or CIS or a Charge Coupled Device or CCD to scan a document.

Sound Card:

The sound cards are also known as audio cards or sound boards.

This computer peripheral is actually an Integrated Circuit or an expansion card. The IC enables the computer to produce sounds that can be heard clearly by the users.

Typically, a computer does not need a sound card and therefore this is considered as a peripheral device.

However, it is included in every system, typically in an expansion slot. Sometimes it is also built in the motherboard.

The sound card is usually located at the back panel of the computer case and has different connections and is usually in the form of audio jacks or 3.5 mm mini plugs.

These slots have different colors to indicate its purpose as well as connector symbols.

The sound card can be used for connecting devices that will help in playing games, listening to music, watching movies, video or audio conferencing, and lots more.


This is another hardware peripheral device that is connected to the sound card of the computer to produce the sound output generated by the sound card.

Speakers usually come with internal amplifiers to enhance the sound volume, quality, and bass but need constant power supplied from the mains supply via battery, AC adapter, or a USB port.

These speakers are usually connected to the computer with a 3.5mm audio jack or RCA connectors but the battery-powered Bluetooth speakers do not need any connection.

The computers, especially the laptop computers, come with built-in speakers but usually offer low-quality output.

When external speakers are connected to it, the internal speakers are disabled automatically.

TV Tuner:

You can also use a TV tuner card with your computer so that it receives TV signals and you can watch it on the computer screen.

Most of the modern TV tuners will also double up as video capture cards.

This means that these tuners can also record TV programs and save them on the hard disk.

There are different types of TV tuner cards available in the market such as analog TV tuner cards, digital TV tuner cards, hybrid TV tuner cards, and combo TV tuner cards.


A short for Uninterruptible Power Supply, the UPS is another useful computer hardware peripheral that offers a backup power source in the event of a power cut, brownout, power outage or blackout, or even a surge in power.

Though the power supplied by the UPS is for a very short time, often ranging anywhere from 5 to 15 minutes depending on the make and model, it is enough to save all your documents that you have been working on.

You can then shut down the system properly without losing any file, fully or partially.

Video or Graphic Card:

These cards are known by different names such as video board, video controller, video adapter and others.

This computer peripheral is actually an internal circuit board. This allows the monitor of the computer to display images.

The main purpose of the video cards is to take the load of graphical processing away from the RAM or the processor.

These cards typically come with their own GPU or Graphics Processing Unit, a dedicated RAM, heat sink to keep the heat out, and several other elements such as shading units, execution units, Texture Mapping Units and more to process high quality graphics quickly.

A graphics card can be added to a computer as an extension card or it can be integrated into the motherboard.

It can come with different expansion ports such as HDMI, AGP, multiple monitors and TV connectivity depending on the model.

Video Projector:

This hardware peripheral device allows projecting the images of the computer screen on a larger surface such as a screen or a flat wall.

This allows everyone present in a large room to see the images.

This is extremely helpful during conferences, business meetings, and presentations where there is a large audience to cater to.


This is a camera connected to the computer that captures images and displays it on the screen.

When connected to the internet, these cameras help in making a video call.

A webcam can be integrated into the computer, as it is found in the laptops, usually at the top bezel of the screen.

Or else, you can also attach a web camera externally to your computer through one of the ports in the motherboard.


Therefore, as it is pointed out by this article, there are different types of computer peripheral devices that can be used for specific purposes.

Now you know how wrong you were when you thought the CPU and the motherboard to be computer peripherals.