The computers where I work were recently upgraded to Windows, but I have trouble using a mouse. Is there anything else I can use to move the cursor on the screen?

The mouse was once considered an optional input device, but with the tremendous popularity of the Microsoft Windows operating environment, which virtually requires a mouse, it has become a necessity. Or I should say, the ability to move an arrow-shaped cursor on the screen has become a necessity. And a mouse has always been necessary to operate an Apple Macintosh computer. But in both cases, a mouse is only one way to move an on-screen cursor.

There are many alternatives to the long-tailed plastic rodent that lives next door to millions of keyboards across the land, but first let me describe how a mouse works. A mouse translates hand motion into cursor motion. Most mice use a rolling ball to turn two rollers -- one for horizontal and one for vertical motion -- which then drive encoders that send signals to the PC. A mechanical mouse uses mechanical encoders. In an optomechanical mouse -- the most common type -- optical encoders use light instead of mechanical contacts to send signals to the PC. Buttons on the mouse are pressed to select on-screen commands or options, or held down while the mouse is moved to move objects around on the screen.

The most popular alternative to the mouse, the trackball, looks like an upside-down mouse with an enlarged ball. Instead of moving the whole device around on your desk to make the ball roll, the housing stays stationary while you simply move the ball with your fingers or the palm of your hand, depending on the trackball’s design. This is very convenient when there is not a lot of desk space to be had, such as when a laptop computer is being used on an airplane. I used a trackball for a number of years and much preferred it to a mouse, both for convenience and for the precision with which I could maneuver the cursor on the screen.

When my track ball died not long ago, however, I decided to try a new gizmo on the market called a GlidePoint. It consists of a small plastic pad about two inches across by about one and a half inches high, on which you simply slide your index finger. This type of input device made its debut on the Apple Macintosh Powerbook line of laptop computers. There is nothing rolling to collect dirt or dust, and no moving parts to wear out. Best of all, it costs less than a number of conventional mice and trackballs on the market. Well, I just love it. Not only do I find it more intuitive to just point and slide my finger to move the on-screen cursor, but instead of having to click a button to execute commands like you do with a mouse or trackball (which you can also do on the GlidePoint, if you prefer--it has three buttons around the pad), you can just tap your finger lightly on the pad either once or twice, depending on whether you’re selecting or moving something on the screen, and the cursor acts as if you had pressed a button.

Anther fairly common input device is a digitizing tablet, having a rectangular surface with sensors embedded in it upon which a wired or wireless electronic pen is moved, thereby moving the cursor on the screen or causing lines to be drawn. Digitizing tablets are used most by those doing computer-aided design (or CAD), or graphic artists who prefer drawing with an electronic pen instead of trying to draw with a mouse. But for ordinary cursor movement, a trackball or GlidePoint is probably your best alternative to a mouse.

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