Basic Components of a Computer System
Input Devices
Input devices are hardware components used to enter data and instructions into a computer. They allow users to communicate with a computer and provide the information it needs to perform tasks.
The computer receives input, processes it according to instructions, and produces output. Some input devices enter text or commands, while others capture images, video, sound, or information from printed materials.
How Input Devices Are Used
An input device converts information from the user or the surrounding environment into a form that the computer can process.
For example, when a user types a sentence, the keyboard sends the entered characters to the computer. The computer can then process the text in an application.
Types of Input Devices
1. Keyboard
A keyboard is a common input device used to enter text, numbers, and instructions.
It contains keys for letters, numbers, symbols, and special functions. When a key is pressed, the keyboard sends a corresponding signal to the computer.
Common uses include:
- Typing documents and messages.
- Entering numbers into spreadsheets.
- Giving commands using keys such as Enter, Esc, and function keys.
2. Pointing Devices
Pointing devices are used to point to, select, and control items displayed on a screen. They make it easier to interact with a Graphical User Interface (GUI), where users work with visual elements such as icons, menus, and buttons.
Common pointing devices include:
- Mouse: Moves a pointer on the screen. Users can click, double-click, drag, and scroll to select or manipulate items.
- Touch pad: A touch-sensitive surface, commonly found on laptops, that controls the pointer when the user moves a finger across it.
- Touch screen: Allows users to select or control items by touching the display directly.
- Joystick: Uses a movable stick to control direction or movement. It is often used in games and simulations.
- Light pen: A pen-shaped input device used to point to or select items on a compatible display.
A user can move the mouse pointer over an application icon and click it to open the application. On a touch-screen device, the user can tap the icon instead.
3. Image and Video Input Devices
Image and video input devices capture visual information and convert it into digital data that a computer can process.
- Digital camera: Captures photographs and stores them as digital image files.
- Webcam: Captures live video, commonly for video calls, online meetings, and recording.
- CCTV camera: Captures video for monitoring and security. The video can be sent to a recording or monitoring system.
These devices are useful when visual information needs to be stored, viewed, shared, or analyzed.
4. Scanners
A scanner converts printed documents, photographs, or other physical images into digital form.
A flatbed scanner is a common type. The document or photograph is placed on a glass surface, and the scanner captures its image.
Scanned material can be stored, viewed, edited, or shared using a computer. However, a normal scan of a page containing text usually produces an image; it does not automatically turn the text into editable characters.
5. Special Input Devices
Some input devices are designed for particular tasks or fields.
- Barcode reader: Reads the pattern of a barcode and sends the encoded information to a computer. It is commonly used in shops to identify products and support checkout systems.
- MICR (Magnetic Ink Character Recognition): Reads characters printed using special magnetic ink. It is used in banking, particularly for processing information on cheques.
- OCR (Optical Character Recognition): Identifies printed or handwritten characters in an image and converts them into machine-readable text. This can make the text searchable or editable.
- OMR (Optical Mark Recognition): Detects marks made in designated areas on forms, such as shaded circles on multiple-choice answer sheets. It is useful when many forms must be checked quickly.
- ATM (Automated Teller Machine): An ATM includes input facilities such as a keypad or touch screen. Customers use them to enter information and select banking transactions.
- Microphone: Captures sound and converts it into a signal that can be processed or recorded by a computer. It is used for voice calls, recording, and voice input.
OCR, OMR, and MICR: Key Differences
| Device or technology | What it reads | Common use |
|---|---|---|
| OCR | Characters in an image of text | Converting printed documents into editable or searchable text |
| OMR | Marks in predefined positions | Reading multiple-choice answer sheets and surveys |
| MICR | Characters printed with magnetic ink | Processing information on bank cheques |
These technologies are not interchangeable. OCR recognizes characters, OMR detects marks, and MICR reads specially printed magnetic-ink characters.
Choosing an Input Device
The suitable input device depends on the type of information being entered and the task being performed.
- A keyboard is suitable for entering text and numbers.
- A mouse or touch pad is suitable for controlling a pointer.
- A camera or webcam is suitable for capturing images or video.
- A scanner is suitable for digitizing printed documents and photographs.
- A barcode reader is suitable for quickly entering product identification codes.
- OCR, OMR, and MICR are used when information must be captured from particular types of printed material.
Key Idea: Input devices allow data, instructions, images, video, and sound to enter a computer. Different devices are designed for different kinds of input.
Exam-Focused Points
- An input device is a hardware component used to enter data and instructions into a computer.
- Pointing devices help users interact with a GUI by pointing to and selecting screen items.
- Know the distinction between OCR (character recognition), OMR (mark recognition), and MICR (magnetic-ink character recognition).
- A scanner digitizes a physical document or image; OCR may then be used to recognize text in the scanned image.
Summary
Input devices provide the computer with data and instructions. Keyboards enter text and commands, pointing devices control on-screen items, cameras capture images and video, scanners digitize physical material, and special devices such as barcode readers, OCR, OMR, and MICR capture specific kinds of information. The choice of device depends on the input required.