What are input and output devices?

Input-output devices help in the functioning of a computer. An input device lets the user enter data into a computer. Common types of input devices are mouse, keyboard, joystick, and microphone. 

An output device is a device that gives or displays the result after processing the input. Examples of output devices are printers, monitors, and speakers.

In other words, an input device provides the data and instructions for the computer to act, and the computer reverts to the action using an output device.

Types of input devices

There are several types of input devices. Some of the well-known input devices are mentioned below:

Keyboard

The widely-used input device in every computer is a keyboard. It contains keys that correspond to an alphabet, number, special character, or commands. A keyboard has 101 to 104 keys. However, nowadays, keyboards with 108 keys are also available. The layout of a keyboard is of QWERTY type. To input data into the computer using a keyboard, the user must press the correct keys on the keyboard. The computer will then process the data according to the instructions given.

Mouse

A mouse is an input device with a small ball and three buttons on the top. It is also known as a pointing device. Using a mouse, the user can click on several icons available on the system and open files or applications. When the computer mouse is rolled across a flat surface, the screen senses its direction, and the cursor moves in the direction of the mouse.

Microphone

A microphone is an input device that converts sound into electrical signals. A microphone is used to record voice, speech recognition, and non-acoustic purposes in a computer.

Bar code reader

A bar code reader is an input device to read bar codes (codes given in light and dark lines). It is a type of optical scanner. A bar code passes a light source, and all the related information is displayed on the computer screen. It can be hand-held or a stationary scanner. 

Scanner

A scanner reads/scans images or text from a paper and transforms it into a digital signal. The information can be stored on the hard disk for manipulation or other purposes. Scanners can be of different types based on their purposes; for example, fingerprint scanners, 3-dimensional scanners, and image scanners.

Optical character recognition (OCR)

OCR is like a scanner, but the process of scanning in OCR is different. It optically scans the text, character-wise, transforms it into machine-readable code, and stores it into the computer memory. The format used by OCR is predefined.

Optical mark reader (OMR)

An OMR is a special type of input device used to check answers to objective-type questions. This type of scanner identifies the mark made using a pen or pencil in the OMR sheet. The answers are then matched to the predefined answer sheet and analyzed for correctness. OMR is extremely useful in automating the answer-sheet analysis of examinations.

Joystick

A joystick is a pointing device that moves the cursor on the computer display. It has a stick connected at an angle with the base and a spherical ball on the bottom and top ends. It can move in all four directions. Joysticks are mainly used for playing games and in airplane cockpits.

Types of output devices

Output devices are of various types. Below are the commonly used output devices.

Monitor

Monitors are popularly called visual display units (VDUs). They are the primary output devices present in all computers and laptops. Monitors are screens that display icons, text, and graphics. There are two types of monitor screens available: cathode-ray tube (CRT) and flat-panel display cathode-ray tube. Flat-panel screens are primarily used in calculators, video games, monitors, and graphical displays.

Speaker

Speakers are output devices through which users can listen to a sound. Computers often come with built-in speakers, but they can also be connected externally. Nowadays, Bluetooth speakers are most used to listen to sound from a computer system. These devices are connected to the computer using Bluetooth.

Printer

A printer is an output device that prints the data from the computer to paper. Printers can be impact printers or non-impact printers.

Impact printers

In impact printers, characters are printed on the ribbon, which is then crushed on the paper. They have an affordable cost but are noisy. Types of impact printers are:

1. Dot-matrix printers: Such printers print characters as a combination of dots positioned in a 5x7 matrix. They can print 60 to 600 characters per second.
2. Daisy wheel printers: Such printers have printing arms in the shape of flower petals. These printers are slower than dot-matrix printers, but they can work as bi-directional printers. Daisy wheel printers are capable of printing 60 to 90 characters in a second.
3. Line printers: Line printers print the total number of lines in a given time. They can print 500 to 1000 lines in a minute.

Non-impact printers

In non-impact printers, the characters are printed without a ribbon. They are called page printers since they print a whole page at a time. They are less noisy and faster than impact printers. Some examples of the non-impact printers are:

1. Thermal printers: Such printers use heat-sensitive paper and print information using the dot-matrix technique. They press hot needles to print characters.
2. Inkjet printers: The ink spraying technique is used to print characters using inkjet printers. The ink is sprayed from tiny nozzles using an electric field that arranges the ink particles into characters. These printers can produce color copies.
3. Laser printers: Laser printers use laser beams that charge the drum negatively. Later, black toner powder is stuck to the drum, and when a paper rolls through the drum, the toner powder is transferred to it. These printers are fast and have a speed of 15,000 to 20,000 lines per minute.

Difference between input and output devices

Context and Applications

Types of input and output devices are a significant concept for computer awareness and general knowledge. The topic is covered in grades 5-12 and several undergraduate and postgraduate courses like:

• Bachelors in Science in Computer Science
• Bachelor in Science in Information Technology
• Masters in Science in Computer Science
• Masters in Science in Information Technology

Practice Problems

1. Which devices does a user use to communicate with the computer system?

1. Input device
2. Output device
3. Software device
4. Both a and b

Answer: Option d

Explanation: The input-output devices help feed data into the computer and provide the result to the user.

2. Which of these devices is not a pointing device?

1. Mouse
2. Joystick
3. Digitizer
4. Light pen

Answer: Option c

Explanation: A digitizer is an input device that transforms analog data into digital form. It is not a pointing device.

3. What type of peripheral device is a printer?

1. Input
2. Output
3. Main memory
4. Storage devices

Answer: Option b

Explanation: A printer is an output device that prints information from the computer to paper.

4. What is a keyboard used for?

1. Input text and numbers and send commands to the computer
2. To create new keys
3. To open the computer
4. To create images and send them to the computer

Answer: Option a

Explanation: A keyboard is used to input text, numbers, and commands into the computer. The computer then processes the instructions and returns the result.

5. Dot-matrix, laser, inkjet, and thermal are all types of which devices?

1. Mouse
2. Printers
3. Storage devices
4. Software

Answer: Option b

Explanation: All of the devices mentioned in the question are types of printers.

Related Concepts

• Computer networks
• Basics of cloud computing
• Computer hardware devices
• Computer software
• Fundamentals of information technology