What Is BIOS?

作者：Coursera Staff • 更新于 Oct 27, 2025

Every time your computer boots up, it relies on BIOS to ensure everything is working properly. Learn more about this firmware and what you can do with BIOS.

[Featured image] A person in a gray hoodie sits at their desk and launches BIOS on their desktop computer.

Key takeaways

Basic input/output system (BIOS) typically comes as a memory chip in your computer’s motherboard, and it activates when you start your device.

BIOS performs diagnostic tests when you boot up your computer, including a power-on self-test that checks out disk drives and other components before searching to ensure the operating system is functioning.

Every computer has its own way to access BIOS, including pressing F1. Check the manual for your device to discover how to open BIOS on your computer.

You can use BIOS to make changes to your computer hardware, including changing the boot order, memory management, and switching the device’s time and date.

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The basic input output system: What is the BIOS in a computer?

BIOS is a type of firmware that usually comes installed on a computer and provides it with instructions to boot up when turned on. Firmware is a form of software or a program embedded in hardware, and in the case of BIOS, it's a memory chip embedded in your motherboard.

When you turn on your computer, BIOS runs a set of diagnostic tests to make sure everything works properly. The initial test is the power-on self-test (POST), and if the computer fails, the system will not boot correctly. This tests peripheral devices like disk drives, video cards, the keyboard, and the mouse, to see if they work properly. After POST, the bootstrap loader searches the computer for a functioning operating system (OS), like , and if it finds one, it turns control of the hardware over to the OS.

BIOS has two other functions: BIOS drivers and BIOS setup. The drivers give your computer control over its hardware, while setup allows you to make configurations to the computer's hardware, like adjusting the time or changing system settings.

Is BIOS in RAM or ROM?

Your device typically stores BIOS in read-only memory (ROM), usually as flash memory, which lets it update as new versions come out.

Why is BIOS important, and what are some things you can do with it?

BIOS setup allows you to make changes to your computer's hardware. Some of the things you can do with it include:

Changing the boot order
Changing system voltages
Changing the date and time on your computer
Changing your CPU settings
Enabling or disabling POST
Changing the power button function
Enabling or disabling onboard audio
Enabling or disabling your computer's logo
Changing your memory settings and viewing the amount of memory you have installed
Changing the settings on your DVD/CD drive
Creating or removing a BIOS password

How to enter BIOS

To access BIOS, power on your computer. As it comes on, you'll see a message that says "Press F1 to enter BIOS setup" or something similar, depending on the computer you have. You may see a different message, but it will usually ask you to press a certain key to enter BIOS. Once you see the message, press the suggested key as quickly as possible.

How do I start BIOS?

Many different options exist for entering your computer’s BIOS, but these may vary slightly for each computer. The best way to know how to enter BIOS for your computer is to consult the manufacturer’s manual for yours. Some common ways to enter BIOS include:

Restart or start your computer: Then press a specified key until BIOS opens, typically Del, F2, F10, or ESC.

Use a command by pressing the Windows key + R type cmd and press enter to pull up the command line: Then type the command shutdown.exe /r /fw and press enter, and your computer will restart and go into BIOS upon reboot.

Enter settings, navigate to Update and Security, then select Recovery from the sidebar: Select Advanced Setup and then the Restart button. Upon restart, select Troubleshoot, navigate to Advanced options, and then hit UEFI Firmware Settings. Your computer will restart again, but boot into BIOS.

How to update BIOS: Can you upgrade or change your BIOS?

Whether you can upgrade your current BIOS chip will depend on your specific device. If you are unable to upgrade but want more memory, you can replace it with a more advanced option. However, if you have a flash BIOS chip, you can update it. Flash BIOS allows you to boot your computer with a special disk or unique set of instructions, and it's not usually found on older hardware.

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