The BIOS – CompTIA A+ 220-1101 – 3.4

The BIOS manages the startup process for our computer systems. In this video, you’ll learn about the fundamentals of a legacy BIOS and a UEFI BIOS.

When you start your computer, something has to begin the process of loading an operating system. On most of our personal computers, this is the BIOS, the Basic Input Output System. This is the software that starts up when you hit that power button. And usually, all of those things you see flying down the screen when you boot up are coming directly from the BIOS software.

This is sometimes referred to as the firmware of your system. It’s the system BIOS or the ROM BIOS, or in some cases, the ROM or flash memory. These days, we don’t generally use Read Only Memory or ROM. Almost everything relating to the BIOS today is stored in flash memory. When you power on your system, it initializes the memory and the CPU, and it begins executing the code of the BIOS.

After the CPU and memory is initialized, you have the post or power on self-test. This is not a comprehensive hardware diagnostics. It’s merely checking to see if you have memory, CPU, video, and some type of input, such as a keyboard or mouse. If all of those components are in place, your BIOS will look to see what you’ve configured to be the boot drive, and then it will look for a boot loader installed on that boot drive so that it can start the operating system.

The flash memory used by the BIOS can usually be found on your motherboard. This motherboard has two separate BIOS configurations, one that is a main BIOS config and a backup BIOS config. This allows you to upgrade the BIOS on your system. And if something goes wrong with the upgrade, you can revert back to the previous version. If you’re working with an older computer, you might have a text-based BIOS like this one. This is the legacy BIOS, and it’s the one that’s been around for about 25 years. Most older operating systems were able to interact with the hardware using this legacy BIOS.

We can make very basic configuration changes from this legacy BIOS, but there’s no way to change or upgrade the capabilities of this BIOS. There’s no way to add additional drivers so that you can connect different network interfaces, and there’s no way to somehow interact or add on to the capabilities of the BIOS itself. The BIOS that’s in our most modern computers is called a UEFI BIOS. The UEFI stands for Unified Extensible Firmware Interface, and it is a standard form of BIOS that can be used across multiple manufacturers.

This is a standard that was created by Intel called the EFI standard or the Extensible Firmware Interface standard. It allows many different manufacturers to create a BIOS that all is standardized on the same features and capabilities. It’s designed to replace a legacy BIOS. So any of the new computers you use today will be using a UEFI BIOS instead of the traditional legacy BIOS.

Here’s a UEFI BIOS emulator that I’m using from HP. You can see there are four different categories– main, security, advanced, and UEFI drivers. There are many different options available in this main section. You can look at the System Information for this particular computer, including serial numbers and hardware configuration. You can look at the date and time and modify that information. Or if you want to perform some diagnostics, it’s built into the BIOS itself.

The next category over is the security category. So if you’d like to add a user or administrator password, you would do all of these settings from the security area of this particular UEFI BIOS. There’s also an Advanced tab at the top so you can change things like the boot options to determine how your system should start up. And this last tab is for UEFI drivers, which is a UEFI-specific capability. This allows you to install additional hardware drivers so that you can interact with other components that may be connected to your computer, such as a network interface card storage or any other hardware device on that system.