What Are The Main Functions Of Bios


What is BIOS?

As your PC’s most important startup program, BIOS, or Basic Input/Output System, is the built-in core processor software responsible for booting up your system. Typically embedded into your computer as a motherboard chip, the BIOS functions as a catalyst for PC functionality action.

There are two different types of BIOS:

  • UEFI (Unified Extensible Firmware Interface) BIOS – Any modern PC has a UEFI BIOS. …
  • Legacy BIOS (Basic Input/Output System) – Older motherboards have legacy BIOS firmware for turning on the PC


BIOS (basic input/output system) is the program a computer’s microprocessor uses to start the computer system after it is powered on. It also manages data flow between the computer’s operating system (OS) and attached devices, such as the hard disk, video adapter, keyboard, mouse and printer.

The 4 functions of BIOS

BIOS identifies, configures, tests and connects computer hardware to the OS immediately after a computer is turned on. The combination of these steps is called the boot process.

These tasks are each carried out by BIOS’ four main functions:

  1. Power-on self-test . This tests the hardware of the computer before loading the OS.
  2. Bootstrap loader. This locates the OS.
  3. Software/drivers. This locates the software and drivers that interface with the OS once running.
  4. Complementary metal-oxide semiconductor (CMOS) setup. This is a configuration program that enable users to alter hardware and system settings. CMOS is the name of BIOS’ non-volatile memory.


Users can access BIOS and configure it through BIOS Setup Utility. Accessing BIOS Setup Utility varies somewhat depending on the computer being used. However, the following steps generally enable users to access and configure BIOS through Setup Utility:

  • Reset or power off the computer.
  • When the computer turns back on, look for a message that says “entering setup” or something similar. Accompanying that message will be a key that the user should press to enter system configuration. Here’s an example message a user might see: “Press [key] to enter BIOS setup.” Some keys often used as prompts are Del, Tab, Esc and any of the function keys (F1-F12).
  • Upon seeing the prompt, quickly press the key specified.

Once in BIOS Setup Utility, users can change hardware settings, manage memory settings, change the boot order or boot device, and reset the BIOS password, among other configuration tasks.


While it’s possible and, in many cases, likely that you will never actively work with your computer’s Basic Input/Output System, it’s one of the most important parts of your computer. The BIOS controls how your computer starts up, makes sure that it’s working properly and serves as a gatekeeper for its various parts. While its default settings are usually more than adequate for most business purposes, most BIOSes are also configurable.


Customizing Your Computer

When you buy a computer, the BIOS frequently comes pre-configured to suit your needs. However, you can change the BIOS settings as well. If you wish to squeeze as much performance out of your computer as possible, you can change configuration options like the CPU clock speed and voltage to force it to run faster. In a business setting, you might choose to prevent the computer from booting from anything other than the hard drive, then enter a password to prevent the setting from being changed. This can stop employees or third parties from using an optical disk or USB drive to boot an alternate operating system, bypass your security, and steal data.


Once the computer loads the operating system, the BIOS doesn’t fade into the background. It’s still there providing low-level drivers and information to help the computer’s various parts work together. When your operating system needs to talk to the hard drive, for instance, it doesn’t have to know how or where your hard drive is attached. It just sends the message to the BIOS, which takes care of passing it along to the correct drive on the correct socket.

Booting Up

Assuming that everything is working correctly on your computer, the next step that the BIOS takes is to load the operating system into memory. It looks at its settings to determine which drive is designated as the “boot” drive and goes to a special section of that drive to find a small piece of code, sometimes called a Master Boot Record, to load into memory. The code tells the computer how to load the operating system; once it’s executed from memory, the computer takes over from the BIOS and starts loading the OS and booting up.

Detecting Components and POST

When you first turn on your computer, the BIOS looks at all of the devices that are connected to your computer. It then runs a series of tests called a Power-On Self Test on the computer and on connected devices to make sure that they are working properly. If they aren’t, it gives you an error code to let you know which component is malfunctioning.

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Author: refuge_2020

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