Input devices Device that accepts data and instructions from the outside world Keyboard Mouse Trackball Joystick Light pen Touch Screen Scanner Bar code Reader
Input devices(contd…) OMR OCR MICR Digitizer Speech Recognition Devices Vision-input System
1. Keyboard For entering text and data. Collection of switches. Each character which when pressed on the keyboard is encoded into the computer system’s data coding scheme and is stored in memory. It includes Alphanumeric keys: A-Z,0-9, tab, caps lock, backspace, enter, shift, ctrl, alt, function keys. Cursor movement keys Numeric keys Special purpose keys: Esc, Print screen, delete, pause
keyboard
Working of Keyboard Keyboard Controller Keyboard Buffer System Software CPU
2. Mouse Point and draw device. Handheld device that allows us to select and moves items on our screen. Rolls on a flat surface and controls the pointer. The pointer on the screen is shown with an arrow( ). Right Button Left Button
3. Trackball Pointing device similar to mouse. Ball is placed on the top with buttons of trackball. Movement of the cursor is controlled by the movement of balls by the fingers. Often used with several equipment having embedded computer e.g. ultrasound machine.
4. Joystick Pointing device that works on the principle of trackball. Consists of a small vertical lever mounted on the base that is used to steer the screen cursor around. Used in video games, flight simulators, training simulators, and remote control of industrial robots.
5. Light Pen Pen shaped device used to select the screen position by detecting the light coming from the points on the CRT screen. Consists of a photocell. The light from the screen causes the photocell to respond when the pen is pointed directly at the lighted area. Used for corrections in architectural designs, to denote loop holes in fielding during telecast of cricket matches etc.
6. Touch Screen Enables user to choose from available options by simply touching the desired icon or menu with his/her finger. Used in mobile phones, banks, ATM, airports etc.
7. Scanner An input device that translates paper documents into an electronic format that can be stored in a computer. Two commonly used types are: Flatbed scanner:
7. Scanner(contd…) Handheld Scanner: Can be held in a hand to do scanning. cheaper than flatbed scanners. Are used where the documents to be scanned are quite less.
8. Bar Code Reader Scans a bar code image and converts it into alphanumeric value. Use laser beam technology for reading bar codes. Commonly used in supermarkets, department stores etc.
9. Optical Mark Reader(OMR) Capable of recognizing a pre-defined type of mark made by pen or pencil. Used in objective type exams.
10. Optical Character Recognition (OCR) Scanner is equipped with OCR software that converts the bit map images of characters to equivalent ASCII codes. OCR software is very complex. Two special OCR fonts are OCR-A and OCR-B Fig: OCR-A fonts
11. Magnetic Ink Character Recognition(MICR) Characters are written by using an ink with special magnetic properties and with special font. Used for reading cheque number and draft numbers. E-13B & CMC-7 are commonly used MICR devices.
12. Digitizer Input device used for converting pictures, maps, and drawings into digital form for storage in computers. Used commonly in the area of CAD by architects and engineers to design cars, buildings, robots etc.
13. Speech Recognition Devices Input devices that allow a person to input data to a computer by speaking to it. Operates by matching an input phrase against a predefined dictionary of words and phrases. Limited success because of different accent and the fact the meaning of words can vary depending on the context in which they are used.
Vision-Input System Allows a computer system to accept input by seeing object. Used in factories for designing industrial robots used for quality control.