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Input Devices in Computer
The input devices are used for supplying program and data to the memory. In other words, the computer system reads the program and the data from the input devices. Most common input devices are the keyboard and mouse.
Following are some of the important input devices which are used in a computer −
Magnetic Ink Card Reader(MICR)
Optical Character Reader(OCR)
Bar Code Reader
Optical Mark Reader(OMR)
The keyboard is the most common and very popular input device which helps to input data to the computer. The layout of the keyboard is like that of the 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 104keys or 108 keys are also available for Windows and Internet.
The keys on the keyboard are as follows −
|Category||Keys & Description|
|1.Typing keys||These keys include the letter keys (A-Z) and digit keys (09) which generally give the same layout as that of typewriters.|
|2.NumericKeypad||It is used to enter the numeric data or cursor movement. Generally, it consists of a set of 17 keys that are laid out in the same configuration used by most adding machines and calculators.|
|3.FunctionKeys||The twelve function keys are present on the keyboard which are arranged in a row at the top of the keyboard. Each function key has a unique meaning and is used for some specific purpose.|
|4.Control keys||These keys provide cursor and screen control. It includes four directional arrow keys. Control keys also include Home, End,Insert, Delete, Page Up, Page Down, Control(Ctrl), Alternate(Alt),Escape(Esc).|
|5.SpecialPurpose Keys||Keyboard also contains some special purpose keys such as Enter, Shift, CapsLock, Num Lock, Spacebar, Tab, and Print Screen.|
The mouse is the 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 the mouse and sends corresponding signals to the CPU when the mouse buttons are pressed.
Generally, it has two buttons called the left and the right button and a wheel is present between the buttons. A mouse can be used to control the position of the cursor on the screen, but it cannot be used to enter text into the computer.
Easy to use
Not very expensive
Moves the cursor faster than the arrow keys of the keyboard.
The joystick is also a pointing device, which is used to move the 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 the joystick is similar to that of a mouse. It is mainly used in Computer Aided Designing (CAD) and playing computer games.
Lightpen is a pointing device 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 the pen button is pressed, its photocell sensing element detects the screen location and sends the corresponding signal to the CPU.
A trackball 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 the ball, the pointer can be moved.
Since the whole device is not moved, a trackball requires less space than a mouse. A trackball comes in various shapes like a ball, a button, or a square.
The scanner is an input device, which works more like a photocopy machine. It is used when some information is available on paper and it is to be transferred to the hard disk of the computer for further manipulation.
Scanner captures images from the source which are then converted into a digital form that can be stored on the disk. These images can be edited before they are printed.
The digitizer is an input device which converts analog information into digital form. The 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.
The digitizer is also known as Tablet or Graphics Tablet as it converts graphics and pictorial data into binary inputs. A graphics tablet as digitizer is used for fine works of drawing and image manipulation applications.
The microphone is an input device to input sound that is then stored in a digital form.
The microphone is used for various applications such as adding sound to a multimedia presentation or for mixing music.
Magnetic Ink Card Reader (MICR)
MICR input device is generally used in banks as there are 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 are that it is fast and less error-prone.
Optical Character Reader (OCR)
OCR is an input device used to read a printed text.
OCR scans the text optically, character by character, converts them into a machine-readable code, and stores the text on the system memory.
BarCode Reader is a device used for reading bar coded data (data in the form of light and dark lines). Barcoded data is generally used in labeling goods, numbering the books, etc. It may be a handheld scanner or may be embedded in a stationary scanner.
BarCode Reader scans a barcode image, converts it into an alphanumeric value, which is then fed to the computer that the bar code reader is connected to.
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 especially used for checking the answer sheets of examinations having multiple choice questions.
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