Input and Output Devices

input and output devices of computer
Input and Output Devices

Computers today are designed to accept input data and instructions, store it and process the data as per user’s instructions and produce the desired results.

What is Input?

Raw data and information collected by the user and entered into the computer with some instructions in terms of formatting and changes for desired output is called the input. Input can be any type of raw data and information or raw figures like census data collected from various places and villages and entered and for collaboration in the computer through input devices and can be viewed with the help of a suitable application in which this raw data can be collaborated and formatted according to the need of its users.

What is Output?

When the user entered raw data into the computer through input devices and a suitable application to view the data. User can give instructions and can apply different formatting on the raw data to make it meaningful. This meaningful data which is given by computer after processing is called the output. For example in census, raw data can be collected by agents in various towns and villages with some particular common fields like name, address, contact etc. and after collecting the raw data it can be collected by the concerned authorities for collaboration. This raw data is the input for the computer and the meaningful data after processing is known as output.

9 Input and Output Devices

Input Devices

The devices which are used to enter data and instructions in the computer are known as input devices. Input devices can take data from user and transfer it to the CPU after converting it into binary form i.e 0 & 1. Below are some important input devices are explained


It helps the user to enter the input into the computer with left and right clicks. It also helps to scroll a document or a file upward and downward. When the user moves the mouse on surface, the mouse pointer moves on the monitor at the same time. The modern mouse is based on sensing light technology which moves the pointer by sensing the surface and movement of user. There are three basic parts of a mouse

  • Scrolling Wheel: It helps to scroll in a window or document up and dow
  • Left Click: It is used to select and drag text, images etc. in a file or in a document.
  • Right Click: After selecting something in a document or window, right click helps to open its properties.

There are three types of mouse

1. Simple Mouse or Mechanical Mouse

Mechanical mouse contains a rubber ball that rolls on the surface of a desk or pad, with the movement of mouse the sensors inside the mechanical mouse can detect the motion and move the mouse pointer on the screen. It also contains left click, right click and scroller.

2. Optical Mouse

Optical mouse is based on optical sensing technique. It contains optical sensing light instead of rubber ball to detect the motion of mouse and translate it into the information that a computer can understand and moves the pointer on screen.

3. Wireless Mouse

Wireless mouse is also based on optical sensing technique or in other words wireless mouse is as same as optical mouse. The only difference between these is the wireless technology as wireless mouse works without any wire while the optical mouse and mechanical mouse needs to be attached to computer with a wire. Wireless mouse can be used with a computer or laptop that has Bluetooth or via an adapter.

Input and Output Devices


A computer keyboard is the primary input devices used to input alphabetical and numeric data into the computer. Similar to a typewriter, a keyboard is the combination of buttons that can create letters, numbers, and symbols, and other functions as well. In the past a computer may have used PS/2, serial ports, and AT (Din5) as a keyboard interface. But most desktop computer keyboards today connect to a computer with USB ports and wire or Bluetooth connectivity for wireless communication with the computer.

Keys of a keyboard

  • Alphabetical Keys: A to Z
  • Numeric Keys: 0 to 9
  • Functional Keys: F1 to F12
  • Symbolic Keys: Symbols like @, #, $, %, ^, &, *, (, ), _, -, =, +, [, ], {, }, \, |, <, >, ? etc.
  • Arrow keys: Up, Down, Left, and Right arrow keys.
  • General purpose keys: Tab key, Caps Lock key, Enter key, Backspace key, Space Bar.
  • Special Keys: Esc key, Shift key, Ctrl key, Properties Key, Alt key.
  • Modified keys: Delete, Insert key, Home, End, Page up, Page down, Num lock, Scroll lock, Pause break, Print screen.

Types of Keyboard

1. Multimedia Keyboard

Multimedia keyboard is one of the most popular types of keyboard. It comes with the multimedia buttons that help users to control media. Multimedia keyboard contains keys like play, pause, stop, next, previous, volume up, volume down, mute, and a special button for launching default music player in the computer. These buttons or keys can be used for controlling videos etc. in Multimedia keyboard users can find buttons to open a default browser for internet and email button to open default email account of the user. Calculator button is also available with these keyboards.

2. Mechanical keyboard

In the mechanical keyboard real physical buttons are used below every key. When a user press a key on the keyboard the button pushes down to an electric circuit and an electrical signal is sent to the computer. User can view the desired results on the monitor. These type of keyboards are cheap and can be used for a long time.

3. Wireless Keyboard

Wireless keyboard use the Radio Frequency, Bluetooth, or Infra-Red technology instead of wire connectivity to send information into the computer. It enable users to use this keyboard with any of computer, mobile, tablet, or laptop that supports wireless technique. These keyboards are light weight and small in size.

4. Virtual Keyboard

Virtual keyboard refers to a non-physical keyboard which allows users to input data into the computer, mobile phone, tablet or laptop. It is not the hardware and is a software or parts of the software. As in a mobile touch phone, users can type through a touch keyboard and there is no need to carry any physical object for this. We can make it disappear after using as per our needs.


The scanner is an electronic machine which is used to store soft copies of photographs, diagrams into the computer. It can capture any document or images from photographic prints, magazine pages and photographs converts a hard copy of data to a soft copy which can be sent to others or used digitally.

Some other input devices are listed below:

  • Light Pen
  • Joy Stick
  • Barcode Reader
  • Digital Camera
  • MICR (Magnetic Ink Character Reader)
  • OMR (Optical Mark Reader)

Output Devices

Output devices refers to the electronic machines that can produce desired output after processing the input data entered by user into the computer. Output devices collect output from computer and convert into human acceptable form and can be viewed or can be printed as per user’s needs. Some main output devices are explained below:


Monitor is an output device which is an important part of the computer. With the help of monitor user can view the ongoing tasks in the computer. It makes a digital interface between computer and user and the data can be displayed on screen. It is also called the Visual Display Unit (VDU) of computer. All the monitors are based on video card which may be positioned on the motherboard or in any other special slot. Resolution of a computer monitor can be measured in pixels.

Types of Computer Monitor:

Input and Output Devices

CRT Monitor

It uses a cathode ray tube (CRT) and show data on screen. CRT is based on a technology used in traditional monitors and televisions. The images on a CRT display are created by throwing electrons from back of tube to phosphors which is located towards the front of display. Electrons hit the phosphors and light up and projected on the screen. The color which we can see on the screen of a computer monitor or television is produced by a mix of red color, blue color, and green color light and often known as RGB.

LCD Monitor

A liquid crystal display (LCD) monitor is a display based on LCD technology which shows clear images. It commonly comes with laptop computers and also called flat panel monitors. LCD technology we can say is the replacement for cathode ray tube (CRT) monitors. As compared to color and picture quality LCD is much better than CRT and are less costly than CRT monitors.

TFT Monitors

The Thin Film Transistor (TFT) are used in high quality flat panel liquid-crystal displays (LCD’s). It contains a transistor for every pixel on the screen. The science behind this is when electrical current illuminates the display to be turned on and off at a faster rate, it makes the display brighter and smoother. The TFT technology used in LCD’s is called active-matrix display and are higher in quality than older passive-matrix displays. It is often known as a high quality flat screen monitor.


A printer is an output device that produces output from a computer in terms of text and images or combination of both images and text on standard size sheets of paper in the form of physical hard copy. Printers are of different sizes, speed, and cost. High resolution color printers are more costly than ordinary printers. There are two types of printers

  • Impact Printers
  • Non – Impact Printers

Input and Output Devices

Impact Printers

Impact printers creates a direct contact between ink ribbon and paper to print the text and images. Impact printers are noisy but quite popular. Some Electro-mechanical devices are used to print in Impact Printers. Printing can be done by hammering a plastic/metal pin or character dye. Examples of impact printers are

  • Dot-matrix printers
  • Daisy-wheel printers
  • Drum Printers
  • Line printers

Non- Impact Printers

Non-Impact printers don’t create any direct contact between ink ribbon and paper. The technology they use is laser, electrostatic, xerographic, and chemical or inkjet to produce printing output in the form of text and images. These printers can produce quality prints and are less noisy. Mechanical moving parts are not used to conduct printing in these types of printers. Examples of Non-Impact printers are:

  • Inkjet printers
  • Laser printers
  • Thermal Printers


Computer speakers refers to output device that produces sound using internal amplifiers vibration at different frequencies as per data received from computer. These are the hardware devices which can transform signals received from sound card into audio form. Without a sound card it is not possible to produce sound from the computer through speakers.

Input and Output Devices


A display device that helps to projects a computer based images and videos onto another surface like whiteboard or wall. A computer transmits the data of an image to the video card and then send that video image to projector. Projectors are used to show PowerPoint and other presentations and for watching videos.

Input and Output Devices


Plotters are used to generate hard copies of digitally designed images and text. Through a graphic card the design is sent to the plotter and then with the help of a pen the design is created. Plotters are commonly used in engineering applications to draws a given image.

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