4th lecture
- 2. definition • A component or peripheral device (such as a barcode reader, graphic tablet, keyboard, magnetic-stripe reader, modem, mouse, scanner, or stylus) that feeds data or instruction into a computer for display, processing, storage, or outputting or transmission.
- 3. Keyboard • Keyboard is the most common and very popular input device which helps in inputting data to the computer. The layout of the keyboard is like that of traditional typewriter, although there are some additional keys provided for performing additional functions. • Keyboards are of two sizes 84 keys or 101/102 keys, but now keyboards with 104 keys or 108 keys are also available for Windows and Internet.
- 4. Mouse • Mouse is most popular pointing device. It is a very famous cursor-control device having a small palm size box with a round ball at its base which senses the movement of mouse and sends corresponding signals to CPU when the mouse buttons are pressed. • Generally it has two buttons called left and right button and a wheel is present between the buttons. Mouse can be used to control the position of cursor on screen, but it cannot be used to enter text into the computer.
- 5. Joystick • Joystick is also a pointing device which is used to move cursor position on a monitor screen. It is a stick having a spherical ball at its both lower and upper ends. The lower spherical ball moves in a socket. The joystick can be moved in all four directions. • The function of joystick is similar to that of a mouse. It is mainly used in Computer Aided Designing(CAD) and playing computer games.
- 7. Light Pen • Light pen is a pointing device which is similar to a pen. It is used to select a displayed menu item or draw pictures on the monitor screen. It consists of a photocell and an optical system placed in a small tube. When the tip of a light pen is moved over the monitor screen and pen button is pressed, its photocell sensing element detects the screen location and sends the corresponding signal to the CPU.
- 9. Track Ball • Track ball is an input device that is mostly used in notebook or laptop computer, instead of a mouse. This is a ball which is half inserted and by moving fingers on ball, pointer can be moved. Since the whole device is not moved, a track ball requires less space than a mouse. A track ball comes in various shapes like a ball, a button and a square.
- 11. Scanner • Scanner is an input device which works more like a photocopy machine. It is used when some information is available on a paper and it is to be transferred to the hard disc of the computer for further manipulation. Scanner captures images from the source which are then converted into the digital form that can be stored on the disc. These images can be edited before they are printed.
- 13. Digitizer • Digitizer is an input device which converts analog information into digital form. Digitizer can convert a signal from the television or camera into a series of numbers that could be stored in a computer. They can be used by the computer to create a picture of whatever the camera had been pointed at. Digitizer is also known as Tablet or Graphics Tablet because it converts graphics and pictorial data into binary inputs. A graphic tablet as digitizer is used for doing fine works of drawing and image manipulation applications.
- 15. Microphone • Microphone is an input device to input sound that is then stored in digital form. The microphone is used for various applications like adding sound to a multimedia presentation or for mixing music.
- 16. Magnetic Ink Card Reader(MICR) • MICR input device is generally used in banks because of a large number of cheques to be processed every day. The bank's code number and cheque number are printed on the cheques with a special type of ink that contains particles of magnetic material that are machine readable. This reading process is called Magnetic Ink Character Recognition (MICR). The main advantages of MICR is that it is fast and less error prone.
- 18. Optical Character Reader(OCR) • OCR is an input device used to read a printed text. OCR scans text optically character by character, converts them into a machine readable code and stores the text on the system memory.
- 20. Bar Code Readers • Bar Code Reader is a device used for reading bar coded data (data in form of light and dark lines). Bar coded data is generally used in labelling goods, numbering the books etc. It may be a hand held scanner or may be embedded in a stationary scanner. Bar Code Reader scans a bar code image, converts it into an alphanumeric value which is then fed to the computer to which bar code reader is connected.
- 22. Optical Mark Reader(OMR) • OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is used where one out of a few alternatives is to be selected and marked. It is specially used for checking the answer sheets of examinations having multiple choice questions.
- 24. Out Put devices
- 25. Definition • An output device is any device used to send data from a computer to another device or user. Most computer data output that is meant for humans is in the form of audio or video. Thus, most output devices used by humans are in these categories. Examples include monitors, projectors, speakers, headphones.
- 26. Printers • Computers were supposed to bring about the dream of a 'paperless office'. This now looks very unlikely to happen because paper has got some advantages over computers when looking at information.
- 27. Laser Printer • This type of printer is the main one used in schools, offices and industry because it produces high-quality printouts very quickly, with good resolution.
- 28. Inkjet Printers • :Basic models of this type of printer are cheap to buy, and let you print in colour. • The quality of the best inkjet's can be very high and can be used for photographs
- 30. Plotters • Plotters are large printer type devices. Instead of using ink cartridges, plotters use pens to draw the output on to paper. With different coloured pens, plotters can produce colour output. • Plotters are capable of producing very accurate drawings and plans. They are most often used in computer aided design (CAD). •
- 32. Sound Card • A sound card captures sounds and changes them into digital binary numbers that are stored as files in your computer.
- 33. Screens and Mointors • Screens are the most common of output devices. They show what's going in the computer. There are really three main types. • ibook transparent screen • Liquid Crystal Display (LCD) Screens. • Thin Film Transistor (TFT) Screens. • Cathode Ray Tube (CRT) Screens •