What is BIOS?
Short for Basic Input/Output System, the BIOS (pronounced bye-oss) is a ROM chip found on motherboards that allows you to access and set up your computer system at the most basic level. The picture below is an example of what a BIOS chip may look like on a computer motherboard. The BIOS pictured is of an early AMIBIOS, a type of BIOS manufactured by AMI.
The BIOS includes instructions on how to load basic computer hardware. It also includes a test referred to as a POST (Power-On Self-Test) that helps verify the computer meets requirements to boot up properly. If the computer does not pass the POST, you hear a combination of beeps indicating what is malfunctioning in the computer.
Adding additional memory to a BIOS chip, as an upgrade, can only be done by replacing the existing BIOS chip with a new, more advanced BIOS chip.
The data on a BIOS chip can be updated if it's a flash BIOS. Using specially designed software, the BIOS can be updated to fix problems or add new features for the motherboard.