Input and Output Devices Of Computer

Peripheral Devices Of Computer

Peripheral devices are those devices that are connected with the computer and work with the computer to perform particular functions. These are the gadgets used to expand the capabilities of the computer to a large extent such as printer, scanner, loudspeaker, etc. When a printer is connected to a computer, you can easily print any type of document by using it. Peripheral devices are also called Auxiliary devices which are depended on the computer & can’t work or perform functions on their own. Peripheral devices may be internal or external. The devices that are connected externally with the computer are called external peripheral devices like printer while those devices which are present inside the computer are called internal peripheral devices like an optical disc drive. A computer is a machine used to perform multiple tasks at extremely very high speed. It includes the various devices which are designed to achieve a specific piece of work or job at a particular time.

The computer is a machine used to perform multiple tasks at extremely very high speed. It includes the various devices which are designed to achieve a specific piece of work or job at a particular time.

Example Of Peripheral Devices:

  • Mouse
  • Keyboard
  • Printer
  • Scanner
  • Projector
  • Speaker
  • Digital Camera
  • Monitor, etc.

Types Of Peripheral Devices:

  • Input Devices
  • Output Devices
  • Storage Devices
  • Input/Output

Input Devices Of Computer

Input devices are those devices that are used to provide input to the computer. The input devices play a very important role in converting the data & instructions into the binary form because the computer can only understand or accepts the binary codes otherwise it does not respond to any other language.

Different types of data can be entered through the input device such as text, graphics images, audio, video, graphical symbols, etc. Different types of input devices are available to process the data. used according to the form of the data

Examples/Types Of Input Devices:

  • Keyboard
  • Scanner
  • Webcam
  • Touchscreen
  • Microphone
  • Light Pen
  • Computer Mouse
  • Graphic Tablet
  • Barcode reader
  • Image Scanner
  • Game Controller
  • Digital Camera


A computer keyboard is a device used for entering data into a computer. The data may be entered by using different characters such as letters, numbers, other symbols. The function performed on the keyboard of entering the text is called typing. The typing is done by using various keys or push-buttons available on a keyboard. When you will press a key on the keyboard, the corresponding character will show on the screen.

Parts Of Computer Keyboard

The keyboard keys are categorized as:

S.No. Keyboard Keys & Their Description
1. Numeric Keys

Numeric keys are used to enter the numeric information. This keypad includes 10 digits (0-9) and mathematical operator (+, -, *, /). These keys are also used for cursor movement. Numeric keypad is consists of a set of 17 keys and it is located on the right side of the keyboard.

2. Character Keys/Alphanumeric Keys

These keys are used to enter characters. It letters (a-z, A-Z), numbers (0-9), space bar, punctuation. It also includes some modify keys which are used to modify the functions of other keys like shift, ctrl (control key), alt (alternate key) and these keys are used in concert with other keys.

3. Punctuation Keys

Punctuation keys are also available on the computer keyboard like the semicolon (;), the colon (:), the question mark (?), single quotes (‘) and double quotes (“).

4. Function Keys

Functions keys are present in a row at the top of the keyboard. There are 12 functions keys (F1-F12) in a keyboard and each key is used for a unique purpose.

5. Special Purpose Keys

The special-purpose keys are space bar, Caps Lock, Num Lock, Del, Page Up, Page Down, Print Screen, Tab, etc. All these keys are known for performing special functions.

6. Cursor Movement Keys

These keys are used to move around the screen (left-to-right or from top-to-bottom).



The mouse is one of the most important devices of the computer. It is also called a pointing device. This pointing device is represented on the screen in the form of an arrow & this arrow is called a cursor. As you move the mouse the cursor/arrow will also move on the screen. It consists of two buttons right & left and a small wheel between the buttons. The left button is used for the options while the right button is used for selecting the options. The mouse is used to control the movement of the cursor on the screen and it is connected with the computer by using a wire. But wireless mouses are also available now that do not require any wire to connected with the computer. It moves the cursor faster as compared to the arrow keys on the keyboard but it is not used for the text typing. To move the cursor on the screen we need to move the whole mouse on a smooth surface.


Trackball is a pointing device used in many laptops to control cursor. It consists of a half inserted ball and you can easily move the pointer by moving or rolling this ball with your fingers. It comes in various shapes like a square, button, etc. It does not require a smooth surface & nor to move the whole device like a mouse. It covers less space than a mouse.


Joystick is also a pointing device used to control the cursor. It has a stick contain balls at both of its upper as well as lower ends. It can move the pointer in all the four directions (left/right & forward/backward). It is generally used in Computer-Aided Designing (CAD), playing computer games.

Light Pen

Light pen is an input device used to point to demonstrated objects. It is also used to draw things/pictures on the monitor screen. It is just like a pen. It contains photocells & an optical system fixed in a small tube. So, when someone moves the tip of the light pen over the screen, pressed the pen button. Then the elements of the photocells will detect the location of the screen and will transmit the signal to the processor (CPU).

Touch Screen

The touch screen is an input device that neither requires a mouse to control the cursor & nor a keyboard to type the content. It just needs a touch by your finger to supply input to the system. Touch screen is a special device that can detect the touch of a finger on a specific point of the screen & sends the corresponding signal to the CPU. By just touching a finger on your screen you can select a particular thing, drag, etc. It means it is a supplement of a mouse as it is a self-capable device of performing the functions of a mouse. It is consists of a special pressure-sensitive screen.

Types Of Touch Screen:

  • Resistive
  • Capactive
  • IR

There are three types of touch screens usually used in monitors:

  • Resistive: Resistive touch screen technology is composed of several layers (generally electrically conductive and resistive layer). The upper resistive circuit layer is made up of polyester while the lower resistive circuit layer is made up of glass. Both of these layers are coated with conductive ITO (Indium Tin Oxide). When you touch and then, press the screen with your finger at a point, both the upper & lower layers become connected at that point. It will cause changes in the electric current and this will called the touch event, will be transmitted to the Processor for further processing.
  • Surface Wave: Surface wave touch screens depend upon the sound waves such as ultrasonic waves, the waves have very high frequency above the limit of human hearing. These type of touch screens operate by capturing these waves.
  • Infrared (IR): Infrared touch screens are consist of glass at both top as well as the bottom. IT depends upon the light beam interruption technology. It consists of LEDs and Sensors placed vertically & horizontally just opposite to each other.

Optical Mark Reader (OMR)

Optical mark reader is an input device that has a light (laser light). It is used to read the existence or non-existence of a pencil or pen mark. In simple words, you can say that it is a scanner used to It is mainly used to check OMR sheets used in several exams. The OMR sheets are the specialized sheets where you get four options in spherical balls (option A, B, C, D). The students have to mark one of these options by a black ball pen. By doing so it becomes easy to check whether the marked answers are correct or not. These sheets are put in the scanner (OMR) which has been already connected to the computer system that has the original sheets with correct answers. The light that has been used in the scanner is more reflected or passed through the white color as compared to the black color. A light is already present on the correct option which is not visible to us but the OMR scanner can detect it. Hence, it makes possible to check the number of OMR sheets of several exams by using this device.

Magnetic Ink Character Recognition (MICR)

MICR is a microprocessor used for character-recognition. It is mainly used in bank sector for clearance of cheques and other documents. We all have seen that there are few digits at the bottom of a cheque. These digits are magnetic micro-fonts and are called MICR Code. They had been written by a special ink made up of iron oxide. The MICR microprocessor contains a magnetic filament that can only recognize the magnetic micro-fonts or characters written by the special ink of iron oxide. So, when the cheque is passed through this device it reads the digits, processes them and then, gives the information like bank name, branch name, name of the account holder, etc. So, it is very helpful in reading the characters & then, executing the information at extremely high speed.

Barcode Reader

Barcode is a code made up of few black colored lines (as black color much absorbs light) some of them are thick and some of them are thin. This can be usually seen on the products. The device used to scan this barcode is called barcode reader/scanner. Barcode Reader is a gun-shaped input device produces a red beam of light (infrared light as it much reflects light) & this red beam of light reads/target the printed barcode of the product. After that, an output will be executed on your PC & shows complete information about the product like the product’s name, its price, etc.

Scanner/Image Scanner

Scanner is an input device used to scan documents, images, etc. It works just like a photocopy machine, scan the information accessible on the paper & ten, transfer this scanned information into the computer for further processing. It converts the information into the digital format. Images captured/taken from the source by the image scanner to scan them & then converted them into the digital form to store them into the computer’s disk. Before printing these stored images you can easily edit them through a software called Adobe’s Photoshop.

Smart Cards

Smart cards are the electronic device, also called a stored-value card. They contain a microchip (integrated circuit chip) embedded into them. The smart cards are used to store customer-specific information like deposit amount, withdrawal amount, personal information of the customer, bank name, etc. The withdrawal/deposited amount and the amount left in the account can be easily detected after every transaction by using this device. It includes a Pin code that is unique for every specific customer. It means it provides security keys to you so, that no unauthorized person can access your account or get any kind of information about it. Smart cards are used in ATM called Automatic Teller Machine from where we can withdrawal/deposit our money without interacting with any bank agent.

Digital Cameras

Digital cameras are used in many fields like smartphones, production lines, traffic monitoring, in many other industries, etc. Digital cameras are consists of a lens & a sensor (usually CCD charged coupled device). Lens is used to focus on the object while the sensor is sensitive to light and is used to store images electrically & also detects color content, brightness level of the image.


Microphones are used to communicate through audio. It is the most commonly used audio communication system in computers. They are used to magnify & record sounds, transfer sound inputs to the computer. They are connected to the motherboard of the computer system as there is an in-built sound chips in the motherboard. Microphones catch the sound, produced signals & then, sent them to the sound cards of the computer. These sound cards are allowed to convert these analog signals into digital signals.

Infrared Remotes

Infrared remotes are depended on infrared technology used to control the various computer devices without making use of any wire. At the top of these remotes, there is a small LED which emits infrared light in a particular pattern to complete a particular task of functions that you want from them to perform. It consists of a keypad and below the keypad, there is a circuit plate. For each button there is a rubber/plastic buttons. So, when you will press any button the circuit will be completed & got informed that which action you want to perform them. These remotes do not show any compatibility with each other. It means that they are liable to perform functions for a specific brand or you can say that they are Brand/Model specific. The remote of a Samsung sound player will perform functions only for the sound players belongs to the Samsung company. The behind this is that each company includes some particular codes so that no interference will be their other the remotes belonged to other companies.

Graphic Tablets/Digitizer

Digitizer is an input device connected with the computer to draw graphics or art into a computer by using a pen. It is mainly used by graphic designers. It consists of a pressure-sensitive pad and a pen connected with the system unit. You can draw anything on the pad by using a pen. The output of your hand-drawn graphic will be produced on the computer. Due to its flat surface, it is also called Graphic Tablet.

Output Devices Of Computer

Output devices are the devices on which the output is generated and they are also able to convert the information into a form that can be easily understood by humans. The different types of outputs can be produced by the output devices.

The output devices are categorized into main two categories according to the type of output produced:

  • Soft-copy Output Device
  • Hard-copy Output Device
Soft-copy Output: Soft-copy output is an intangible output (cannot be touched) & temporary. It disappears when the computer is switched off. The soft-copy output is displayed on the screen may be in the form of e-mails, a digital word document. The soft-copy output devices electronically display information on the computer screen.

Examples Of Soft-copy Output Devices are:

  • Computer Monitor
  • Speakers
Hard-copy Output: Hard-copy output is an tangible output (can be touch) in nature & it is available on a paper may be in the form text, graphics. The information written or printed on a paper is called hard-copy. The hard-copy output may be in the form of a book, a letter, etc.

Examples Of Hard-copy Output Devices are:

  • Printer
  • Plotter

Computer Monitor

A computer monitor is one of the most important output device. It is also called Visual Display Unit (VDU) as it is allowed to display information visually. It consists of very small dots called pixels that are arranged in a particular pattern so that they do not overlap each other. These pixels together form an image. The sharpness of an image depends upon the number of pixels present in a screen. Means the more the number of pixels available in a screen the better will be the picture quality of the screen. The maximum number of pixels per unit area of the screen is called resolution.

There are different types of monitors available to the users:

  • CRT Monitors: It stands for Cathode Ray Tube which includes beam penetration method. Three electron guns are present in these type of monitors like RGB (Red, green & blue). These electron guns transmit or radiate a constant flow of electrons through an electric field. The two phosphors layers are available, one is inside the tube & other at the outer surface of the tube. The displayed colors are based on the fact that how far electron beam penetrate (enter) into these layers. CRT monitors include different phosphors that are responsible for emitting different colored light. These emitted light get combined to generate a wide range of colors (new colors). Hence, it is the combination of phosphors which can emit different colored light which results in a colored picture on the monitor.
  • LCD Monitors: LCD stands for the liquid crystal display. Crystal is something whose elements lie between liquid & solid and the LCD screens are neither a complete liquid and nor a crystal. It is an intermediate between these two. It shows the properties of a crystalline solid in which molecules are arranged in a specific pattern but does not have a fixed shape. Polarization is present in LCD screens which allows the movement of light in one direction. Three colors are needed to glow a pixel i.e. red, green & blue (RGB). When voltage is applied the molecules of crystal regulate in one direction, these molecules are passed and it polarizes the light (from vertical to horizontal) and also controls the intensity of light.
  • TFT Monitors: TFT stands for thin-film transistor. It is mainly used in laptops. This type of screen is very sensitive and have better resolution than the LCD screen. It includes independent and tiny transistors for each pixel. It has great visual clarity. They use less power and it’s display gets refreshed many times per second.


Speakers are used to generate audio output. They are useful in producing outputs in the form of sounds that can be easily listened/caught by the user to listen to music, many other sound effects. They are available in various forms. Some speakers are already connected with the computer while some wireless speakers are also available that are connected by Bluetooth. 200 to 500 watts speakers are used for a personal computer that can generate sound effects for a small area/room. To produce large sound effects for large area amplifiers speakers and woofers are used to produce low-frequency sounds. Amplifier is an electronic circuit & is used to enlarge the signals while woofers. Laptops include speakers that cover restricted space and produce low-quality sound.


Printers are used to generate hard copies of the electronic data stored on the computer on various types of papers according to the requirement of the user. Wireless printers are also available & can be connected with the Bluetooth. There are two wireless technologies of printers for printing that are challenging the previous technology are Bluetooth and Infrared. The Bluetooth printing device passes on output to a printer through radio waves while infrared printing technology uses infrared light waves.
Character per second (CPS), lines per minute (LPM), or page per minute (PPM) are the units in which the speed of the printer is measured.

The different types of Printer are:

  • Impact Printer
  • Non-Impact Printer

Impact Printer

Impact printers are the printer that works just like a typewriter and prints the characters & images by striking  a needle or a print hammer on the paper. They include ink ribbon that strikes against paper to make a mark on it. Its name self defines it that it has a hammer which impacts on the paper. Impact printers are further divided into the following categories:

(1) Character Printers: These are the printers which can print a single character at a time in a serial order. That’s why they are also called Serial Printers. They are just capable of printing characters. These printers have the following features:

  • low cost.
  • low speed.
  • generally used with personal computers.
  • produce a lot of noise during printing.

Types of Character Printers:

  • Dot Matrix Printer: It is a printer whose head is consists of a matrix of dots or hammer (usually 9 or 24) & they are placed in rows and columns. It works when an appropriate number of pins strike against  the head of the printer to print the characters on the paper and can also print images but of low quality.
  • Daisy Wheel Printer: Daisy wheel is a printer consists of a plastic disk or you can say that it includes the circular printing mechanism. The plastic disk includes characters at its outer edge & it prints the characters by rotating the disk until the desired character is facing the paper.
Line Printers: Line printer is a machine that prints a single line at a time rather than a character at a time. Its speed ranges from 250-2500 lines per minute.

Types Of Line Printers are:

  • Chain Printer: Chain printers are the printers depends upon the moving chain mechanism in which chain moves and it rotates until the desired character comes, then the hammer strikes the chain. The chain includes the multiple number of characters that reduces the number of rotations of the chain.
  • Drum Printer: Drum printer is a printer that is consists of a metallic drum which includes characters arranged in columns on it. When the appropriate character comes at the printing point, the hammer strikes the paper as well as the inked ribbon to print a particular character.

Non-Impact Printers

Non-Impact printers are the printers which print characters without striking/touching an ink ribbon against the paper. They include heat, pressure, laser technology to print the characters. Its speed is fast as compared to the impact printer. It can print colored output. The different categories of non-impact printers are:

Inkjet printer: Inkjet printers contains liquid ink in the cartridges or ink tanks.  The cartridges have tiny nozzles to spray the ink onto the paper. Its photo-printing is quite good as the ink blends nicely. You can print on different types of sheets. The less power is consumed by this type of printers. The liquid ink is very easily & quickly absorbed by the paper. They are less costly as compared to laser printers.
Laser printer: Laser printer includes dry toner in the powdered form. It consists of a cylindrical drum at which a laser beam strikes where the user wants to print. When paper is placed with the drum, due to the heat it strikes onto the paper. Its printing speed is fast & consumes more power than the inkjet printer. Its text-print quality is quite good as compared to the photo-printing. They are more expensive than inkjet printers.


Plotters are looked just like a printer but they both are different in their technologies. They are mainly used for vector graphics in a variety of colors. Vector graphic is an image with very high resolution. They are used to create pictures on a broad or extensive paper. They are used to generate line drawings with more accuracy. They are consists of a pen or a pencil to produce a line on paper. They are also called graphics plotters. Graphic plotters are more expensive as compared to the printers. They are quite useful in engineering drawings.

Types Of Plotters:

  • Drum Plotter: Drum plotters are consists of a drum & the paper is rolled on this drum. This drum rotates and moves to draw according to the design to draw graphs, images, etc. Drum plotter makes very much noise and is more compact as compared to the flatbed plotter.
  • Flatbed Plotter: Flatbed plotters are the plotters consists of flat surface, also called bed to which a paper is adjusted. They include a set of pens that moved on the paper to draw images.

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