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Mice and Other Pointing Devices

Description: The mouse is an input device used to allow two-dimensional movement, usually through the action of a small rubber ball and a pair of perpendicular rollers. It is used by graphical operating systems such as Windows to allow motion of a pointer or cursor, and control and selection of objects using one or more integrated buttons.

The mouse is used in combination with the keyboard and found in one form or another in just about every PC. Other pointing devices have been developed over the years that function as replacements for mice but operate in a slightly different way: for example, trackballs and pressure-sensitive touch-pads. The general concept of all is the same: two-dimensional controlled motion of the hand or fingers that translates into similar motion on the screen.

Role and Subsystems: The mouse is an input device and is part of the input subsystem. It usually connects to the motherboard through the mouse port on the motherboard, though older systems often used a serial port, and some models now connect using USB.

Related Components: The mouse is related to the motherboard, but due to the fact that the PS/2 mouse interface is now quite standardized, it has no real impact on motherboard purchasing decisions. Mice are also somewhat related to keyboards, of course.

Key Compatibility Selection Criteria: The only compatibility selection criterion of any significance when it comes to pointing devices is the interface between the device and the system. Pointing devices are engineered to allow connection to the system in one of the following four ways:

• PS/2 Port Only: The device connects to the system through the small, round, six-pin mini-DIN connector specially provided on the motherboard for the mouse. The name comes from the IBM PS/2 system that first used it.
• Serial Port Only: The mouse connects to the system through a standard 9-pin serial I/O port.
• "Combo" PS/2 and Serial: The mouse or other device can be connected to either the PS/2 port or serial port. Usually the cable ends with a PS/2 connector and a mechanical adapter is provided to convert the mouse to a serial connector for serial use. See the note below.
• USB: The mouse connects to the system through a USB port.

Note: The existence of PS/2 to serial adapters causes a lot of confusion, because many PC users think any PS/2 mouse can be used in a serial port if they attach that adapter. This is not so; the mouse must be specifically designed as a "combo mouse" and the adapter must be used. Most switch automatically to handle either interface, but some have a switch on the bottom.

Most systems today provide a dedicated PS/2 mouse port and use a regular PS/2 mouse. "Combo" mice provide more flexibility, especially with older systems that may not have a PS/2 mouse port. USB mice are gaining in popularity but are still far outnumbered by the other types. (Some very old systems use what is called a "bus mouse" but these are rarely seen today.)

After you have decided on the interface, the next decision is what sort of pointing device you want. Most people use a regular mouse, but some prefer other devices, such as trackballs (essentially an upside-down mouse whose ball you move with your thumb) or touchpads (touch-sensitive pads most commonly found on notebook PCs). This choice is a matter of personal taste, as the devices all serve the same function.

Performance and Capacity Selection Criteria: Not applicable.

Quality Selection Criteria: Pointing device quality is very subjective and depends on the user's sensitivity to pointing device problems. Personally, I cannot stand using a cheap mouse that doesn't roll properly, stutters and feels awkward in the hand; I buy good quality mice for say $30 or $40 and keep them for years, and I feel it is worth it. Other people are perfectly happy with the cheapest mouse they can find, or even one that is free after rebate from a local computer store (or salvaged from an obsolete PC).

As with all input devices, check the unit out in person and choose one you like. Bear in mind that cheap mice are more apt to fail after prolonged use than ones made by a good company--you might end up spending that $30 a bit at a time over a period of many years anyway, while not enjoying any of the benefits of good construction in the meantime.

One option available to you now is to go with an optical mouse. New units by manufacturers such as Microsoft and Logitech replace the conventional ball and roller mechanisms of traditional mice with a light source and motion sensor. You can use the mouse on most surfaces without having to worry about the mouse pads, dirt accumulation or cleaning issues associated with mechanical mice.

Finally, another important quality issue is the software that comes with the mouse. Cheap mice come with very basic software, but better mice come with nice utilities that let you test the unit, control various aspects of its operation, program buttons and so on. Again, the choice is yours.

Important Features: The basic mouse provides two buttons, and if you get a mouse with a new PC you may get this simple type. However, there are dozens of different designs around now, many including extra features such as these:

• Extra Buttons: Three, four or even more buttons are provided on some mice. These usually can be programmed to perform operations such as executing a double-click, bringing up the start menu, or simulating a function key press.
• Scroll Wheel: A small mechanical wheel is integrated into a button or the body of the mouse. Moving the wheel allows you to browse a document vertically without moving the mouse pointer. The rise of Web browser use has made this a very popular feature that is now working its way down to even rather inexpensive rodents.
• Cordless Mice: The mouse comes with an interface piece that plugs into the PC and communicates with the actual mouse unit, eliminating the cord. Expensive, but nice if you hate cords. :^)

"Magic Numbers" To Watch For: None.

Performance Impact: None.

Retail, OEM and Gray Market Issues: Not really a big issue since mice are not items that fail regularly and are almost cheap enough to be considered disposable.

Importance of Manufacturer: Depends on your quality sensitivity, as I mentioned before. I usually use Logitech mice because I like their feel, quality and features, but many people do just fine with generics.

Typical Component Lifetime: This depends entirely on the quality of the unit, but they usually last years.

Warranty Issues: Nothing particular.

Driver Support Issues: Windows provides native support for regular mice, but some operating systems do not. For DOS applications you will probably have to load a mouse driver. USB models or those with special features require a driver.

Special Specification Considerations: Here are a couple of suggestions:

• As I recommended for keyboards, if you buy a PC that comes with a mouse that you don't like, get one you prefer. Your sanity is worth a few dollars. :^)
• Inexpensive mouse extension cables are available from most computer stores. These can eliminate problems with the mouse not being able to reach the PC from where you want to use it.

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