A basic input/output system (BIOS) is an electronic set of instructions that a personal computer (PC) uses to boot successfully. It is located on a chip on a computer’s motherboard and is designed to protect against drive failure. While it can be updated, this must be done carefully to avoid damaging your computer or preventing it from starting. Certain computer manufacturers, such as Apple™, use other systems such as Open Firmware.
A screenshot of a BIOS setup screen.
BIOS function
One of the primary functions of the BIOS is to provide instructions for the Power On Self Test (POST). This self-test ensures that your computer has all the parts and functionality it needs to start properly, such as memory usage, keyboard, and other components. If errors are detected during the test, the computer provides a code that reveals the problem. Error codes usually present as a series of beeps heard shortly after startup.
A computer motherboard.
The BIOS also works to provide the computer with basic information on how to interact with some critical components, such as hard drives and memory, needed to load the operating system (OS). After loading the basic instructions and passing the self-test, the computer can continue to load the operating system from one of the attached drives. The functions and control of the hardware inside the computer are then transferred to the operating system, which then controls the system.
A CMOS chip, which contains the information that the BIOS needs to start up.
How is it stored on a computer?
Traditional BIOS firmware is included on the computer’s motherboard as read-only memory (ROM). This means that the system is accessible, but is not dynamically recorded in the same way as a computer’s hard drive during operation. A battery on the motherboard keeps data intact, even when the computer is turned off while not in use. Although sometimes confused with Complementary Metal-Oxide Semiconductor (CMOS), BIOS refers to the firmware on the motherboard, while CMOS is the physical location where date and system configuration data is stored.
A BIOS chip allows a computer to properly boot up the boot process.
Many PC manufacturers today use flash memory to maintain this system, allowing users to more easily upgrade computers. This may resolve issues with the original BIOS or add new features to it. Users can periodically check for new versions, as some vendors release multiple updates during the life of a product. To find an update, users should check with the motherboard manufacturer. These updates must be done with care, as incorrect versions or corrupted software can make your computer unbootable.
BIOS configuration and control
PC users can make certain system settings through a configuration screen on the computer. The setup screen is normally accessed with a special key sequence during the first few moments of boot, usually “Delete” or a function key. This setup screen allows users to change the order in which drives are accessed during startup, monitor temperatures of computer components, and control the functionality of various devices. Most computer users never need to access these systems on their computer, although many simple bug fixes may require tweaking.
Updating a BIOS chip requires professional-level knowledge to prevent damage to the machine.
