Page 17 - Computer Science Class 11 With Functions
P. 17

OCR             Keyboard


                                 Mouse                                            Scanner



                                                      Input Devices
                             Bar Code
                              Reader                                                        Trackball






                                                                                         MICR
                                     Joystick
                                                     Touch Panel       Touchpad

                                                       Fig 1.4: Input Devices


                     Name the input device for the following:
                     1.  Converts an image on paper to digital form.
                     2.  A device used to automate the evaluation of multiple-choice questions, whose answers have been
                        marked by darkening circles against the correct answers.
                     3.  A device that scans the fingerprint of employees for attendance.



            1.3 Output Devices

            The output devices receive data from a computer and deliver the desired output on a suitable device for a user. It
            converts digital data into a human-understandable form. Some of the commonly used output devices are described
            below:

            1.3.1 Monitor

            A monitor or a Visual Display Unit (VDU), popularly known as a screen, is the most commonly used output device.
            The monitor is organised in the form of picture elements (pixels), often arranged in a rectangular array. A pixel is the
            smallest unit of graphical information on the computer screen. The size of a monitor is expressed in terms of the length
            of the diagonal of the display unit. Thus, a 15-inch (38 cm) display may be 12 inches (30.48 cm) wide and 9 inches
            (22.86 cm) high and may comprise 1024×768 pixels. Pixel dimensions (say, 1024×768) are also called pixel resolution.

            1.3.2 Printer

            A printer is an output device that produces the output on paper. Paper output is also known as hard copy and often
            includes text and images. Nowadays, laser printers are most popular as they produce high-quality permanent output.
            In contrast, thermal printers, often used for billing at restaurants, petrol pumps, and several shops, produce outputs
            that fade away with time. Previously, dot matrix printers were very popular because they produced low-cost outputs.
            1.3.3 Plotters

            A plotter is an output device used for printing high-quality images and drawings such as maps, architectural layouts
            and designs.




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