To make the movement of the spherical ball easier the

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Unformatted text preview: allows easier movements of the mouse. Trackball A trackball is a pointing device that is similar to a mechanical mouse. As shown in Figure 9.5, the ball that is placed in the base of a mechanical mouse is placed on the top along with the buttons in case of a trackball. To move the graphics cursor around the screen, the ball is rolled with the fingers. Because the whole device is not moved for moving the graphics cursor, a trackball requires less space than a mouse for operation. Since it need not be moved for moving the graphics cursor, it is often attached to or built into the keyboard. Trackballs built into the keyboard are commonly used in laptop (notebook) computers because a mouse is not practical for laptop users in a small space. Because the ball is fixed on the top, some people find it helpful to think of a trackball as an upsidedown mouse. A trackball comes in various shapes and forms with the same functionality. The three commonly used shapes are a ball, a button, and a square. In case of a ball, the ball is rolled with the help of fingers to move the graphics cursor. In case of a button, the button is pushed with a finger in the desired direction of the graphics cursor movement. In case of a square plastic, the finger is placed on top of it and moved in the desired direction of the graphics cursor movement. Joystick A joystick is a pointing device that works on the same principle as a trackball. To make the movement of the spherical ball easier, the spherical ball, which moves in a socket, has a stick mounted on it (see Figure 9.6). Instead of using the fingers in case of a trackball, the user of a joystick moves the spherical ball with the help of the stick with his/her hand. The stick can be moved forward or backward, left or right, to move and position the graphics cursor at the desired position. Potentiometers are used to sense the movements. On most joysticks, a button on the top is provided to select the option, which is currently pointed to by the cursor. The button is clicked...
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This document was uploaded on 04/07/2014.

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