This chapter is from the book
This chapter is from the book
This chapter is from the book
Mice and Keyboards
Input devices, such as the mouse and keyboard, attach to the motherboard. The most common type of mouse is an optical mouse, which has optical sensors that detect the direction in which the mouse moves. It uses reflections from light-emitting diodes (LEDs) from almost any surface to detect the mouse location. Mice commonly can be adjusted for sensitivity—how far you have to move the mouse to move the cursor on the screen a desired amount. Mice are rated in dots per inch (DPI), or how many dots (pixels) on the screen the mouse moves per square inch. The higher the number, the more sensitive the mouse. Mouse sensitivity can range from 100 to 6400 DPI; mice with higher DPI numbers are typically used for gaming or design. Figure 1.20 shows a photo of the bottom of an optical mouse.
Figure 1.20 Optical mouse
A keyboard is an input device that connects to a port on the motherboard or attaches wirelessly. Features users look for in a keyboard include a separate numeric keypad for those that have to input a great deal of numbers, adjustable tilt legs, and spill resistance. Figure 1.21 shows the type of keyboard and mouse that are commonly used with a tower, desktop, or all-in-one computer.
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Figure 1.21 Keyboard and mouse
Mouse and Keyboard Preventive Maintenance
Mouse cleaning kits are available in computer stores, but normal household supplies also work. Use the following procedures to clean an optical mouse:
> Wipe the bottom with a damp, lint-free cloth.
> Use compressed air to clean the optical sensors.
Keyboards also need periodic cleaning. Figure 1.22 shows keyboard-cleaning techniques.
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Figure 1.22 Keyboard cleaning techniques
Keyboard/Mouse Troubleshooting
One of the easiest ways to determine whether a keyboard is working is to press the 
or 
key and watch to see if the keyboard light illuminates. Sometimes an application setting may be causing what appears to be a keyboard problem. Use another application to see if the keyboard is the problem. Keyboards can have LED lights that indicate particular functions. Table 1.3 lists the most common ones. Note that different vendors label the lights in various ways.
Table 1.3 Common keyboard lights
Associated toggle key |
Keyboard light |
Description |
|---|---|---|
|
Number lock (NUM LOCK) |
Toggles the 10-key pad between digits 0 through 9 and various functions, such as HOME, PG UP, PG DOWN, END, and various arrow keys. |
|
Capital letters lock (CAPS LOCK) |
Toggles between all uppercase and lowercase letters. |
|
Scroll lock |
A rarely used key used to prevent scrolling and use of the arrow keys to progress through information displayed. |
If coffee or another liquid spills into a PC keyboard, all is not lost. It is sometimes possible to clean a PC keyboard by disconnecting it, removing any batteries it might have, and soaking it in a bathtub or a flat pan of water. Distilled or boiled water cooled to room temperature works best. Afterward, the keyboard can be disassembled and/or scrubbed with lint-free swabs or cloths. However, PC keyboards and mice are normally considered throw-away technology. It is cheaper to get a new one rather than spend a lot of time trying to repair it.
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