Following are some of the important input devices which are used in a computer −
Keyboard is the most commonly used and very popular input device which helps in typing the input data to the computer in order to give the output. The looks like that of traditional typewriter, although there are some additional keys provided to perform 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.
The keys on the keyboard are as follows −
|S.No||Keys & Description|
Mouse is the most popular pointing device. It is a very popular cursor-control device that looks like a small palm size box with a round ball at its base, which helps in the movement of the mouse and sends corresponding signals to the CPU when the mouse button is pressed.
Generally, it consists of two buttons called the left and the right button and a small wheel like ball is present in between the buttons. A mouse is used to control the position of the cursor on the screen, but it cannot be used to enter text into the computer. It looks like a mouse, hence the name mouse.
Joystick is also a pointing device, which is used to move the position of the cursor on a computer screen. It looks like a stick with a spherical ball at its both lower and upper ends. The lower spherical ball moves in a socket, it is adjusted in the socket itself. 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.
Light pen is also a pointing device which looks like a pen. It is used to select a displayed menu item or helps to 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.
Track ball is a type of an input device that is mostly used in notebook or laptop computer, instead of a mouse. This looks similar to that of mouse except the inserted ball which is big in size. 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 track ball requires less space than a mouse. A track ball may be in different shapes like a ball, a button, or a square.
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 output source which are then converted into a digital form that can be stored on the disk. These images can be modified before they are printed.
Digitizer is an input device which converts analog information into digital form. It has the capacity to convert a signal from the television or camera into a series of numbers that could be stored in a computer. Later stage this stored information can be used by the computer to create a picture where the camera had been pointed at.
Digitizer is also known as Tablet or Graphics Tablet as it converts graphics and pictorial data into binary inputs. It looks like small size tablet. A graphic tablet as digitizer is used in works of drawing and image manipulation applications.
Microphone is an input device to input sound that is then stored in a digital form.
The microphone is used for various applications like adding sound to a multimedia presentation when you present in front of people or for mixing music.
MICR input device is generally used in banks to process the large number of cheques every day to the customers. 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 advantage of MICR is that it is fast in assessing and less error prone.
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.
Bar Code Reader is an input device used for reading bar coded data (data in the form of light and dark lines). Generally, this bar coded data is used in labelling goods, numbering the books, etc where we often find in shopping malls when we purchase something. It may be a handheld scanner or may be embedded in a stationary scanner.
Bar Code Reader scans a bar code image which then converts it into an alphanumeric value, and later entered into the computer that the bar code reader is connected to.
OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is used to find out the selected and marked one among the alternatives.
It is specially designed for checking the answer sheets of examinations with multiple choice questions.
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