INPUT AND OUTPUT DEVICES

INPUT DEVICES

An input device is a hardware device used to enter data and control signals into a computer or other information-processing system.

Examples of Input Devices

• Keyboard
• Mouse
• Scanner
• Digital Camera
• Joystick
• Barcode Reader
• Light Pen
• Microphone
• MICR
• OCR
• OMR

IMPORTANT INPUT DEVICES

1. KEYBOARD

A keyboard is a basic input device used to enter data and instructions into a computer by pressing keys.

It contains different groups of keys for:

• Letters
• Numbers
• Symbols
• Functions
• Special operations

Keyboards may be connected to a computer through USB or Bluetooth for wireless communication.

Common Types of Keyboard Keys

Type of Key	Description
Typing Keys	Include alphabet keys (A–Z) and number keys (0–9).
Numeric Keypad	Used to enter numerical data and perform cursor movement. It generally contains 17 keys.
Function Keys	Twelve keys, usually F1 to F12, arranged at the top of the keyboard. Each performs a specific function.
Control Keys	Used for cursor and screen control. Examples include Arrow Keys, Home, End, Insert, Delete, Page Up, Page Down, Ctrl, Alt, and Esc.
Special Purpose Keys	Include Enter, Shift, Caps Lock, Num Lock, Spacebar, Tab, and Print Screen.

2. MOUSE

A mouse is a hand-held pointing input device used to move the cursor or pointer across the computer screen.

A typical mouse contains:

• Left button
• Right button
• Scroll wheel

Laptop computers generally use a touchpad that performs functions similar to a mouse.

Common Types of Mouse

• Trackball Mouse
• Mechanical Mouse
• Optical Mouse
• Cordless or Wireless Mouse

3. SCANNER

A scanner is an input device that scans pictures, documents, and text.

It converts the scanned material into a digital format that can be stored and displayed on a computer.

Optical Character Recognition (OCR) techniques may be used to convert printed or handwritten text into digital text.

Common Types of Scanners

• Flatbed Scanner
• Handheld Scanner
• Sheet-fed Scanner
• Drum Scanner
• Photo Scanner

DOCUMENT / IMAGE

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SCANNER

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DIGITAL COMPUTER FILE

4. JOYSTICK

A joystick is a pointing input device similar to a mouse.

It consists of a movable stick attached to a base. The movement of the stick controls the cursor or pointer on the screen.

It is commonly used in:

• Computer games
• Simulators
• Control systems

5. LIGHT PEN

A light pen is a pen-shaped input device.

Its tip contains a light-sensitive detector that enables the user to point to or select objects directly on a display screen.

The light-sensitive tip detects the location of the object and sends the corresponding signals to the CPU.

6. DIGITIZER

A digitizer is an input device consisting of a flat surface that is generally used with a stylus.

It enables users to:

• Draw images and graphics.
• Write using a stylus.
• Convert handwritten input into digital form.

The images or graphics created on the digitizer appear on the computer screen.

7. MICROPHONE

A microphone is an input device used to enter sound into a computer.

It receives sound vibrations and converts them into audio signals. These signals are then converted into digital data and stored or processed by the computer.

SOUND

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MICROPHONE

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AUDIO SIGNAL

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DIGITAL DATA

8. MAGNETIC INK CHARACTER RECOGNITION (MICR)

MICR is a character-recognition technology used to read characters printed with special magnetic ink.

It is widely used in:

• Banks
• Cheque processing
• Organisations where security is important

9. OPTICAL CHARACTER READER (OCR)

OCR is an input technology used to convert scanned images of:

• Handwritten text
• Typed text
• Printed text

into digital, machine-readable text.

It is widely used in:

• Offices
• Libraries
• Document digitisation

10. BARCODE READER

A Barcode Reader is a device used to read barcoded data consisting of light and dark lines.

Barcodes are commonly used for:

• Labelling goods
• Product identification
• Book numbering
• Inventory management

A barcode reader may be:

• Handheld
• Built into a stationary scanner

11. OPTICAL MARK READER (OMR)

OMR is a special type of optical scanner used to detect marks made with a pen or pencil.

It is commonly used when one option must be selected from a number of alternatives.

Example: Objective-type answer sheets.

OUTPUT DEVICES

An output device displays or presents the result of data processing performed by the computer.

Output may be presented in the form of:

• Text
• Images
• Hard copies
• Audio
• Video

Important Output Devices

• Monitor
• Graphic Plotter
• Printer
• Projector

1. MONITOR

A Monitor, also known as a Visual Display Unit (VDU), is the primary output device of a computer.

It displays images using tiny dots called pixels.

The greater the number of pixels, the better the image resolution and clarity.

Main Types of Monitor Displays

MONITOR

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CRT DISPLAY                 FLAT-PANEL DISPLAY

A. CATHODE-RAY TUBE (CRT) MONITOR

A CRT display forms images using small picture elements called pixels.

The smaller the pixels, the better the image clarity or resolution.

A character is formed by a number of illuminated pixels.

Characteristics of CRT Monitors

• Large in size.
• Heavy.
• Consume a large amount of power.
• Require more physical space.

B. FLAT-PANEL DISPLAY

Flat-panel displays have reduced:

• Volume
• Weight
• Power requirements

compared with CRT monitors.

They are used in:

• Calculators
• Video games
• Desktop monitors
• Laptop computers
• Graphics displays

Types of Flat-Panel Displays

FLAT-PANEL DISPLAY

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EMISSIVE DISPLAY              NON-EMISSIVE DISPLAY

│                       │

Plasma, LED                  LCD

1. Emissive Displays

These displays convert electrical energy directly into light.

Examples:

• Plasma Display
• LED (Light-Emitting Diode)

2. Non-Emissive Displays

These displays use optical effects to convert light from an external source into graphical patterns.

Example:

• LCD (Liquid Crystal Display)

2. PRINTER

A printer is an output device that produces a hard copy of processed data.

It can print:

• Text
• Images
• Documents
• Other information

Based on the printing mechanism, printers are broadly classified into:

PRINTERS

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IMPACT PRINTERS          NON-IMPACT PRINTERS

A. IMPACT PRINTERS

Impact printers print by physically striking an ink ribbon against the paper.

1. Character Printers

• Dot Matrix Printer
• Daisy Wheel Printer

2. Line Printers

• Drum Printer
• Chain Printer

B. NON-IMPACT PRINTERS

Non-impact printers print without physically striking the paper.

Examples:

• Laser Printer
• Inkjet Printer

3. PROJECTOR

A projector is an output device that projects computer output onto a large surface, such as a screen or wall.

It uses light and lenses to produce magnified:

• Text
• Images
• Videos

A projector is particularly useful for:

• Presentations
• Classroom teaching
• Training programmes
• Displaying information to a large audience

COMPUTER

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PROJECTOR

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LARGE SCREEN / WALL

1. Which of the following is an input device?

A. Monitor
B. Printer
C. Keyboard
D. Speaker

Answer: C. Keyboard

2. Which device is used to enter text and numbers into a computer?

A. Keyboard
B. Monitor
C. Projector
D. Printer

Answer: A. Keyboard

3. Which of the following is a pointing device?

A. Printer
B. Mouse
C. Speaker
D. Monitor

Answer: B. Mouse

4. Which device is used to convert a printed document into a digital form?

A. Scanner
B. Printer
C. Plotter
D. Projector

Answer: A. Scanner

5. Which of the following is an output device?

A. Keyboard
B. Mouse
C. Scanner
D. Monitor

Answer: D. Monitor

6. Which device produces a hard copy of a document?

A. Printer
B. Monitor
C. Keyboard
D. Microphone

Answer: A. Printer

7. Which device is used to input sound into a computer?

A. Speaker
B. Microphone
C. Monitor
D. Projector

Answer: B. Microphone

8. Which device is commonly used to display computer output on a large screen or wall?

A. Scanner
B. Projector
C. Keyboard
D. Joystick

Answer: B. Projector

9. OMR is mainly used to:

A. Read magnetic ink
B. Read marked answers on forms
C. Print documents
D. Scan barcodes

Answer: B. Read marked answers on forms

10. Which device is used to read printed characters and convert them into editable digital text?

A. OCR
B. MICR
C. OMR
D. Plotter

Answer: A. OCR

11. Which of the following is an output device?

A. Keyboard
B. Mouse
C. Monitor
D. Scanner

Answer: C. Monitor

12. LCD stands for:

A. Light Crystal Display
B. Liquid Crystal Display
C. Light Control Display
D. Liquid Computer Display

Answer: B. Liquid Crystal Display

13. LED stands for:

A. Light Emitting Diode
B. Light Electronic Display
C. Liquid Emitting Diode
D. Light Energy Device

Answer: A. Light Emitting Diode

14. Which type of monitor uses a cathode-ray tube?

A. LCD
B. LED
C. CRT
D. OLED

Answer: C. CRT

15. CRT stands for:

A. Computer Ray Technology
B. Cathode-Ray Tube
C. Central Ray Tube
D. Cathode Reading Technology

Answer: B. Cathode-Ray Tube

16. Which of the following is a flat-panel display?

A. CRT
B. LCD
C. Dot Matrix Printer
D. Drum Printer

Answer: B. LCD

17. The sharpness and clarity of an image on a monitor mainly depend on:

A. Keyboard
B. Resolution
C. Printer speed
D. Storage capacity

Answer: B. Resolution

18. A screen image is made up of tiny dots called:

A. Bytes
B. Pixels
C. Bits
D. Characters

Answer: B. Pixels

19. Which of the following is generally considered more energy-efficient than a traditional CRT monitor?

A. LED monitor
B. Dot Matrix Printer
C. Plotter
D. Mechanical Mouse

Answer: A. LED monitor

20. Which of the following is an input device?

A. Plotter
B. Monitor
C. Light Pen
D. Projector

Answer: C. Light Pen

21. Which device is used to read bar-coded information?

A. OCR
B. Barcode Reader
C. OMR
D. MICR

Answer: B. Barcode Reader

22. MICR is mainly used in:

A. Schools
B. Banks
C. Hospitals
D. Railway stations

Answer: B. Banks

23. MICR reads characters printed using:

A. Invisible ink
B. Magnetic ink
C. Optical ink
D. Carbon ink

Answer: B. Magnetic ink

24. OMR is commonly used for:

A. Reading marked answers on examination sheets
B. Printing documents
C. Playing audio
D. Displaying images

Answer: A. Reading marked answers on examination sheets

25. OCR is used to:

A. Read magnetic ink
B. Recognise marked bubbles
C. Convert printed or scanned text into digital text
D. Print text

Answer: C. Convert printed or scanned text into digital text

26. Which of the following is a soft-copy output device?

A. Printer
B. Monitor
C. Plotter
D. Typewriter

Answer: B. Monitor

27. Which device produces a hard copy?

A. Monitor
B. Projector
C. Printer
D. Speaker

Answer: C. Printer

28. Which of the following is an impact printer?

A. Laser Printer
B. Inkjet Printer
C. Dot Matrix Printer
D. Thermal Printer

Answer: C. Dot Matrix Printer

29. Which of the following is a non-impact printer?

A. Daisy Wheel Printer
B. Dot Matrix Printer
C. Drum Printer
D. Laser Printer

Answer: D. Laser Printer

30. A plotter is mainly used to print:

A. Large technical drawings and graphics
B. Audio files
C. Keyboard commands
D. E-mails only

Answer: A. Large technical drawings and graphics

31. Which device is used to display computer output on a large screen?

A. Projector
B. Scanner
C. Mouse
D. Microphone

Answer: A. Projector

32. Which of the following is used to input voice into a computer?

A. Speaker
B. Microphone
C. Monitor
D. Projector

Answer: B. Microphone

33. Which device is used to produce sound output from a computer?

A. Microphone
B. Speaker
C. Scanner
D. Keyboard

Answer: B. Speaker

34. A joystick is mainly used for:

A. Playing computer games and controlling movement
B. Printing documents
C. Scanning documents
D. Displaying images

Answer: A. Playing computer games and controlling movement

35. Which of the following is an example of a touch-sensitive input device?

A. Touchscreen
B. Printer
C. Speaker
D. Projector

Answer: A. Touchscreen

36. Which device is used to draw directly on a computer using a stylus?

A. Digitizer
B. Printer
C. Speaker
D. Projector

Answer: A. Digitizer

37. Which of the following is NOT an input device?

A. Keyboard
B. Scanner
C. Mouse
D. Printer

Answer: D. Printer

38. Which of the following is NOT an output device?

A. Monitor
B. Printer
C. Projector
D. Keyboard

Answer: D. Keyboard

39. A monitor is also commonly known as:

A. Visual Display Unit (VDU)
B. Central Processing Unit
C. Digital Processing Unit
D. Visual Processing Unit

Answer: A. Visual Display Unit (VDU)

40. Which monitor technology uses liquid crystals?

A. CRT
B. LCD
C. Dot Matrix
D. VDU

Answer: B. LCD