BIOS Detail Tutorial

The BIOS is a ROM chip located on the motherboard.

The BIOS (Basic Input/Output System) is like the brain of your computer; when you press the power button, the BIOS proceeds through several tests before allowing your operating system to boot. You may also hear the BIOS referred to as the CMOS, which is actually the term for the interface used to make changes to the BIOS. The BIOS keeps information using a battery on the motherboard that keeps it running when the computer is off.

Instructions

Power On Self Test (POST)

1. Checks the hardware of the system to make sure that everything necessary to boot is accounted for and functioning. It does this by accessing the periphal BIOS, which is the BIOS of each individual device; the peripheral BIOS interacts with both the BIOS and your operating system in order for the device to function. When something is broken or missing, you may hear a series of beeps known as the beep codes; every motherboard has a different set of beep codes that indicate the problem.

2. Locates any new hardware; if you've installed a new DVD drive or extra RAM, the BIOS detects this and accommodates for it, allowing your operating system to recognize the hardware when it boots up.

3. Finds the operating system and turns the system over, allowing your operating system boot process to start; once you've gotten to this point, the BIOS has more or less decided that everything is in place and is supposed to work.

Making Changes to the BIOS

1. Enter the CMOS by pressing your computer's trigger key. The specific key varies depending on your computer's manufacturer, but is usually displayed on the initial boot screen in the form of "Press Del to Enter Setup." Common keys are the "Del," "F1," "F2," and "F10."

2. Enter the password, if one has been set. If you have not set a password, but your CMOS asks for one, consult your computer's manual for information regarding the password.

3. Take a moment to really read your CMOS screen; before making any changes it's best to make sure that you understand where you are and what the current settings are. Some settings cannot be changed, such as chipset or PCI behavior, while others are customizable.

4. Make changes cautiously. You can use the CMOS to change the boot order of your drives, which changes the order that the BIOS loads your drives; this is most commonly used if you're trying to boot from CD or USB drive. Other customizable changes include power settings, time and date, security, and device settings.

5. Exit the CMOS and save your new settings. Your computer will reboot, with your new BIOS settings taking place during the boot process.

Tips & Warnings

• Some people choose to password-protect their BIOS; if you choose to do this, make sure that it is a password that is easy to remember but hard to guess, in order to ensure your security and avoid accidentally locking yourself out of the BIOS.

• Check your motherboard's manufacturer website for a list of beep codes; keeping beep codes somewhere on hand can help you quickly diagnose a problem when one occurs.

• Modifying your BIOS may cause boot trouble; make sure that you understand what you are changing before modifying the BIOS settings, and double-check before making changes to things that you don't quite understand.

References

• College of Oneonta: Understanding the BIOS
• Computer Hope: How to Enter the BIOS or CMOS Setup