With such an user interface the basic requirement is

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Unformatted text preview: system much more efficient and smooth. This is because when the keystroke is made, the processor may be busy doing something else and may not be in a position to immediately transfer the keyboard input to the main memory. In this case, if there was no keyboard buffer, the keyboard would have got locked after every keystroke, not allowing the user to enter anything till the keyboard input was transferred to the main memory and the lock was released. This would have caused severe problem and delay in data entry especially for data entry operators with fast typing speeds. The keyboard buffer helps in overcoming this problem by allowing the user to enter keyboard inputs at their own convenient speed. The keyboard inputs are stored in the keyboard buffer and the processor keeps transferring them to the main memory whenever it gets time to attend to the keyboard device. Point-and-Draw Devices Interaction with computers was initially restricted mainly to text mode. However, it was soon realized that interacting with computers in text-mode is cumbersome and timeconsuming. Hence a new type of interface, called graphical user interface (GUI) was devised for interacting with computers. As shown in Figure 9.3, a GUI provides to the user a screen full of graphic icons (small images on the screen) or menus and allows the user to make a rapid selection from the displayed icons or menus to give instructions to the computer. With such an user interface, the basic requirement is to have an input device that can be used to rapidly point to and select a particular graphic icon or menu item from the multiple options displayed on the screen. The keyboard was found to be very inconvenient and unsuitable for this requirement. Hence research efforts to find a suitable input device to meet this requirement gave birth to several input devices like mouse, track ball, joystick, light pen and touch screen. Later it was realized that many of these devices like mouse and light pen could also be very effectively use...
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This document was uploaded on 04/07/2014.

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