Most people use the mouse that comes with their machines without giving it much thought.

The mouse is a small object that is designed to fit neatly under the palm of your hand. It is defined by two qualities:

1. You move it in two dimensions, and
2. you activate it by pressing its buttons.

Supplementing your keyboard, the mouse takes full advantage of a PC's or Macintosh's graphical interface. It allows you to navigate the screen and select items on it. The mouse is the most common kind of pointing device. Others include the trackball, the pointing stick, touch pad, digitizer, light pen, and touch screen.

HOW A MOUSE WORKS

The ball on the underside is the key. As it rolls, it brushes against two rollers set at right angles inside the mouse. These turn precisely to reflect the mouse's horizontal and vertical motions.

The rollers are each connected to a small wheel that has slots around its rim.

The slotted wheels rotate and alternately block and unblock light from a diode (a device or debit that allows electrical currents to travel in one direction only). The computer calculates the rate of the blinking light and determines how fast the mouse is rolling in each direction. It then adjusts the cursor to the same degree on the screen.

Most people use the mouse on a mousepad though this isn't necessary. The pad's rubbery surface gives the ball more traction than a smooth desktop does, however, the sponginess reduces stress on the hand.

Generally you can do a couple of things. One is to choose an item, which can be a menu choice, an icon; or a button. You do this by pressing the mouse's primary button either once (clicking) or twice (double-clicking). If the unit has two or more buttons, the primary one is usually the one on the left.

Pressing the button normally makes a distinct sound, hence the term "clicking."

Clicking an option activates it just as if you had pressed Enter on the keyboard. The software responds with another display.

You can also use the mouse to highlight something, such as text in a document. Simply move the cursor to the beginning of a word, sentence, or paragraph and click.

But instead of letting go, hold the button down and drag the cursor across the text. You often can highlight something by duble-clicking it, too.

After you select an object - a shape in a graphics program, a cell in a spreadsheet, words in a word processor - you can move it by dragging it.

Again, click the item but hold down the primary button. A highlight or outline should appear around the item to show it is in oplay. Without releasing the button, tow it to a new location. Let go of the button when you have reached the designated spot. This drops the item in place, hence the phrase "drag and drop."

You can emulate most mouse actions with the computer keyboard. Indeed, pressing keystroke combinations is faster for tasks such as choosing menu options. But dragging and droppingf objects is laborious with the keyboard. If it is possible at all. A pointer is a real timesaver in a Windows environment.

MAINTENANCE

A mouse does not need much attention. It is a simple device and rarely breaks down. But if its motions seem slow or erratic, it may need cleaning. (Just don't soak it in the bathub).

• Turn off the computer. Turn over the mouse to expose the ball. The ball may have a retainer ring around it, which you can twist and take off. Or it may have a place attached with screws, which you can undo.
• Remove the ball and examine the interior. Blow out any accumulated dust or lint. The rollers may be especially dirty, so use a cotton swab dipped in rubbing alcohol to clean them. If grit is caked on and swabbing is not enough, gently use a toothpick to scrape it off.
• Wash the ball with a mild detergent or rubbing alcohol. Let it dry in the air or wipe it with a lint-free cloth. When both it and the mouse's interior are dry, replace the ball and reattach the the ring or plate.

INSTALLING A MOUSE

To install a mouse, plug it into the receptacle (the port), on the back of your PC. If you already have a device attached to this port, unscrew the screws holding the plug in place and disconnect it. As you can see, the plug has nine holes to match the port's nine pins.

Plug the new device into the port, gently rocking it if necessary to ensure a firm fit. Don't force it; if the plug doesn't attach easily, you may have it backward. When is is in place, secure it with its screws.

Because Windows includes the standard drivers (programs that allow hardware peripherals, such as input devices, to communicate with a computer), a simple mouse; should work as soon as you turn on the PC.

More advanced tools come with their own software drivers to give you sophisticated control over the device. Install these programs as you would any others.