BIOS stands for Basic Input/Output System. BIOS is the firmware used to start your computer. BIOS may be referred to as the System BIOS or ROM BIOS because this firmware used to be stored on a Read Only Memory (ROM) chip on the motherboard. Modern computers store the BIOS on flash memory. Some motherboards have 2 BIOS chips. One is a backup BIOS.
BIOS allows the computer to talk to the hardware without an operating system.
When you first turn on your computer the BIOS starts the CPU and memory. The BIOS also performs a check called POST which stands for Power On Self Test. The POST check verifies the CPU, memory, display and keyboard connected, and other hardware diagnostics. Once POST is completed, the BIOS looks for a boot loader on a storage device to start the operating system.
There are 2 different types of BIOS: 1) The original legacy BIOS 2) UEFI BIOS.
With the legacy BIOS, older operating systems communicated through the BIOS to access hardware, instead of accessing the hardware directly. Legacy BIOS has limited hardware support. It doesn’t have drivers for modern network, video, and storage devices so access to USB interfaces, network interfaces, and storage devices is impossible.
The second type of BIOS is UEFI, which stands for Unified Extensible Firmware Interface. The UEFI was created as a standard so all motherboard manufacturers would have a standard type of BIOS. UEFI was designed to replace legacy BIOS and provide support for modern hardware. UEFI has more graphical user interface.
UEFI provides the following advantages:
- It can boot from large storage devices (greater than 2.2 TB) that have been formatted with GUID partition table (GPT). GUID stands for Globally Unique Identifier.
- UEFI can also boot from FAT (file allocation table) formatted drives and removable drives, such as a USB flash drive.
- UEFI has a pre-boot environment. It’s not an operating system but it has it’s own shell, drivers, and applications which allow you to browse the internet, backup a storage drive, and perform diagnostics.
- UEFI supports 32 bit or 64 bit booting, and its not depended on x86 firmware.
To get into the BIOS System setup, you’ll need to reboot your computer. As the computer boots up, very briefly it will display which key you need to press to enter the setup. It could be the delete key, F2 key, etc. This screen will appear before the operating system loads. So to get into the BIOS system setup, you’ll hold down the specified key while your computer boots up.
On Window 8/8.1, there’s another option to enter the BIOS settings:
1. Display the Charms bar and click on the Settings charm and then click on Change PC Settings. Then click Change PC Settings.
2. In the Settings app, click Update and Recovery. Then click Recovery in the navigation bar.
3. Under the Advanced Startup heading, click Restart Now. Then at the Choose an Option screen, click Troubleshoot, and then click Advanced.
4. In the Advanced Options screen, click UEFI Firmware Settings. The PC will reboot into BIOS settings.
On Windows 10, there’s also another option to enter the BIOS settings:
1. Go to Start. Then Settings.
2. Click on Update and Security. In the Navigation bar, click Recovery.
3. Under the Advanced Startup heading, click Restart Now. Then at the Choose an Option screen, click Troubleshoot, and then click Advanced Options.
4. In the Advanced Options screen, click Restart.
Boot options
If you want to boot from a thumb drive, you’d have to enter the BIOS system setup and check the boot options to make sure the thumb drive has priority in the boot order.
Another use case for configuring the boot options is if you want to lock down the boot options so that the system can only boot from the internal hard drive.
Firmware updates
Updating the BIOS is commonly referred to as “Flashing the BIOS.” UEFI BIOS may provide you with options to update the BIOS within the system setup.
Before performing a firmware update, make sure that you have good power. You don’t want to lose power in the middle of an update. It’s recommended to use a UPS to ensure power.
An incomplete or corrupted BIOS can kill your motherboard so only do a BIOS firmware update if you have a specific reason to do it. If everything is working properly, there is no need to flash the BIOS, even if an updated BIOS is available.
Security settings
There’s an option to put an Administrator password and a user password. If an Administrator password is set, anytime someone tries to enter the BIOS System setup, it will prompt for the Administrator password. If a user password is set, that means anytime the computer boots up, even if not going into the BIOS System setup, the computer will prompt for that user password. This user password prompt occurs before the operating system loads. If the user password is not entered, the computer will not finish the boot up process.
Interface configurations
The BIOS System setup allows you to enable or disable/enable expansion cards, ports, etc. You can adjust LED lighting if your system has them.