Input devices

Input devices:

      We need to input (fed) the data and instructions into the computers to process any task. The input unit consists of one or more input devices. Keyboard is the one of the most commonly used input device. Other commonly used input devices are the mouse.

Punching cards:

   A Punching card is a piece of stiff paper that can be used to contain digital data represented by the presence or absence of holes in predefined positions. 

    Digital data can be for data processing applications or in earlier examples, used to directly control automated machinery. Punched cards were widely used through much of the 20th century in the data processing industry. 

Keyboard:

    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 traditional typewriter(QWERTY), 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.

Mouse:

    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.

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 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 comes in various shapes like a ball, a button, or a square.

Track pad:

     A Trackpad is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user's fingers to a relative position on the operating system that is made output to the screen. Touchpads are a common feature of laptop computers. 

Joystick:

      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.

Stylus pen:

       A stylus (or stylus pen) is a small pen-shaped instrument that is used to input commands to a computer screen,mobile device or graphics tablet. With touchscreen devices, a user places a stylus on the surface of the screen to draw or make selections by tapping the stylus on the screen.

       In this manner, the stylus can be used instead of a mouse or trackpad as a pointing device, a technique commonly called pen computing.

Scanner:

       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.

Light Pen:

         Light pen 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.

Bar Code Readers:

       Bar Code Reader is a device used for reading bar coded data (data in the form of light and dark lines). Bar coded data is generally used in labelling goods, numbering the books, etc. It may be a handheld 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 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 specially used for checking the answer sheets of examinations having multiple choice questions.

Magnetic Ink Card Reader (MICR):

        MICR input device is generally used in banks as there are 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.

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.

Microphone:

       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.

Cam recorder:

    A digital camera or digi-cam is a camera that captures photographs in digital memory. Most cameras produced today are digital, and while there are still compact cameras on the market, the use of dedicated digital cameras is dwindling, as digital cameras are now incorporated into many devices ranging from mobile devices to vehicles. However, high-end, high-definition dedicated cameras are still commonly used by professionals.