Updated: 02/27/2019 by Computer Hope

BIOS may refer to any of the following:

1. 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 example picture below 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 will receive a combination of beeps indicating what is malfunctioning in the computer.

The four main functions of a PC BIOS

  • POST - Test the computer hardware and make sure no errors exist before loading the operating system. Additional information on the POST is available on our POST and beep codes page.
  • Bootstrap Loader - Locate the operating system. If a capable operating system is located, the BIOS will pass control to it.
  • BIOS drivers - Low-level drivers that give the computer basic operational control over your computer's hardware.
  • BIOS or CMOS Setup - Configuration program that allows you to configure hardware settings including system settings such as computer passwords, time, and date.

Can a BIOS chip be upgraded or updated?

Adding additional memory to a BIOS chip, as an upgrade, can only be done by physically removing it from the motherboard and replacing it with a new, more advanced BIOS chip.

The data on a BIOS chip can be updated if it is a flash BIOS. Using specially designed software, the BIOS can be updated to fix problems or add new features for the motherboard.

2. When referring to a person BIO, BIO's is short for biography and is a term used to describe a brief description of a person. A short biography or description of people who have affected the computer industry is on our computer people section.

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