Mouse is the most popular point-and-draw device. It is a must-have input device on modern personal computers and workstation because they supported GUI as their primary user interface. A mouse is a small hand-held device that fits comfortably in a user's plan. It rolls on a small bearing and has one or more buttons on the top. When a user rolls a mouse (connected to a user terminal) on a flat surface, a graphics cursor on the terminal screen in the direction of the mouse's movement. Since movements of the graphics cursor on the screen reproduce all movements of the mouse, we can easily position the graphics cursor at a menu item or an icon by using the mouse.
Different applications display the graphics cursor as different symbols such as an arrow (), a wrist with a pointing finger (), etc. An application may also display the text and graphics cursor on the screen simultaneously. The graphics cursor, irrespective of its size and shape, has a pixel-size point that is the point of reference to decide the position of the cursor on the screen. This point is called hot spot of the graphics cursor. The graphics cursor points to a menu item or icon, when a user positions the hot spot on it. With a click of the mouse's button, a user can notify the system of this choice. Note that notify the system of a particular choice, out of the various options provided by software, is much easier with a mouse than pressing various key combinations. With proper software, we can also use a mouse to draw picture on the screen and edit text.
Commonly used ways to categorize mouse devices are:-
1. Mechanical and optical mouse. A mechanical mouse has a ball inside it that partially projects out through an opening in its base. The ball rolls due to surface friction when a user moves the mouse on a flat surface, On two sides of the ball (at 90 angles from each other) are two small wheels that spin to match the speed of the ball. Each wheel of the mouse connects to a sensor. As the mouse ball rolls when a user moves the mouse, the sensors detect how much each spins and send this information to the computer in the form of changes to the current position of the graphics on the screen.
An optical mouse has no mechanical parts like the ball and wheels. Instead, it has a built-in photo- detector. It comes with a special pad with gridlines printed on it. When a user moves the mouse on the pad, the photo-detector sense each horizontal and vertical line on the pad, and sends this information to the computer in the form of changes to the current position of the graphics cursor on the screen.
2. One, two and three buttons mouse. A mouse can have one, two, or three buttons. A one-button mouse is good enough for programs designed to use only a single button. Some programs operate with a two-button or three-button mouse. If the system has lesser number of buttons, such programs can still run on the system by providing an alternative way to indicate a click of these buttons- such as by pressing shift key on keyboard while the mouse button is clicked. With a mouse having multiple buttons, the leftmost button is the main button that allows for most mouse operations because most people are right-handed and use their right index finger to click the main button. However, a user can configure another button as main button. For example, a left handed user can configure the right-most button as main button.
3. Serial and bus mouse. A serial mouse plugs into a serial port (a built-in socket in a computer's back panel to which we can connect external devices). It does not require a special electronic card for connecting the mouse to a computer. On the other hand, a bus mouse requires a special electronic card, fits into one of the expansion slots of the computer. Thus, a bus mouse occupies on the expansion slots. Whereas a serial mouse does not need any expansion slot.
4. Wired and cordless mouse. A wired mouse connects to a computer with a small cord (wire). On the other hand, a cordless mouse has no wired connection to a computer. It communications with the computer with the help of a controller that operates by transmitting a low-intensity radio or infrared signal. although a cordless mouse is more expensive than a wired mouse, it allows easier movement of the mouse.