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If Windows is the happy face your computer projects to the world, then the BIOS is its dark, brooding subconscious. The BIOS--or Basic Input/Output System--is the code for fundamental PC functions, such as retrieving a keystroke from the keyboard or putting a pixel on the screen. This small program works behind the scenes, translating Windows' people-friendly commands into the zeroes and ones understood by your hardware. And like the human subconscious, the BIOS can have a powerful influence on your PC's behavior and performance.

BIOS Therapy

As new technology emerges and old bugs are discovered, computer makers often issue updated BIOS versions that can solve problems and improve performance. Check your PC maker's Web site for updates. But first, make sure you have the version number of your current BIOS; it usually flashes on your monitor right after you turn on your system. (Press the Pause key if it flashes too quickly.)

Updating your BIOS is easy, but you must do it with care. Usually you need only run a small program from a floppy disk. If a problem occurs, however, you can be left with a useless motherboard. So be sure to read all the instructions in the BIOS update's readme file beforehand. And always do exactly what the directions say.

If the BIOS is your PC's subconscious, then its Setup utility is the foundation on which you build your PC's character. The utility has user settings to control hard disks, memory, graphics cards, power saving, USB ports, and other hardware. The program used to come on a disk, but now it's conveniently stored in the same ROM chip as the PC's BIOS, enabling easy access. To open Setup, just press the key (or combination of keys) that you're prompted to enter when the PC starts up. Different BIOS makers use different keys--typically <Delete>, <F1>, or <F10>. Your screen should announce which key or keys to press for Setup just after it displays the BIOS version number. If it doesn't, check your system's documentation.

Because the Setup utility is made by the BIOS maker and is in the same chip as the BIOS, it's often called the BIOS Setup utility. And because it stores its settings in the clock/calendar chip--a complementary metal-oxide semiconductor, or CMOS, chip--it's also referred to as the CMOS Setup program. (The CMOS chip has its own battery to retain the chip's settings even when the PC is unplugged.)

The Setup utility has an abundance of hardware settings, ranging from the obvious, like one for the time on your PC's clock, to the arcane, such as the number of "wait states" that coordinate the flow of data between the RAM and the CPU.