What is BIOS and how does it work?

This four-letter abbreviation stands for Basic Input Output System. But the name does tell even the have of the story and the capability of this system. Most users think that BIOS is needed just for controlling input and output system. However, its range of actions and options stretches far beyond that. Your operating system and BIOS is a whole, and the OS cannot be loaded without a proper BIOS. In this article, we will explain the principle of BIOS and debunk main misconceptions about it.

BIOS has been around since DOS (Disk Operating System), well even before that time – before Microsoft developed the structured DOS. BIOS is often neglected by users despite the fact being one of the most important components of the system. Yeah, we usually don’t use it on a regular basis, but it does not mean that it is not doing its job. Today we are looking at the very foundation of the system and tell you why computers need it to be able to work properly. 

What is BIOS?

Long story short: BIOS is a piece firmware stored in a miniature chip on your motherboard. It contains a package with instructions written to help with the loading of the operating system installed on the hard drive. No OS will be able to load if there were no BIOS!

When you turn your PC on and wait for it to boot, BIOS instructions are carried out. This includes RAM and processor error checks and much more:  

  • It itemizes each installed module of RAM and checks whether all of them are fully functional.
  • When the processor and RAM are approved for work, BIOS proceeds to check other connected devices.
  • It analyzes all connected peripherals such as your mouse and keyboard and checks available boot options.
  • There are multiple choices available for booting, and all of them (their sequence) can be specified in BIOS: boot from DVD, boot from USB flash drive, boot from LAN, boot from hard drive, etc.
  • Devices’ bootstraps are also checked by BIOS during this process. The order is defined by the manufacturer that configured BIOS or the user.
  • Control over a computer is passed on to the operating system after BIOS loads the essential parts of the OS into OS-reserved section of RAM when bootstrap is located.

Of course, it not a full list of functions, features, and options available in BIOS. It also checks chips such as CMOS to set the time/date on your PC; then it loads the drivers for all installed components into the memory of the computer. It helps the operating system to “understand” what is going on by checking and loading input/output signal to the random access memory (RAM). For instance, if you press a key, BIOS receives a newly generated interrupt requires that must be passed on to the operating system. After getting that request, the OS “thinks” on what action to take, according to its programmed settings.

You may still wonder why your operating system cannot be without BIOS. The answer is simple: OS is always located on one of the connected disks (including removable ones). While BIOS loads the drivers for those disks making them functional in the first place. When disks are alive, BIOS then loads the main sections of the OS: GPT, MBR, FAT, and so on, into memory, which allows the operating system to boot properly and load itself independently from that point.

Applying Changes to BIOS

When needed you can easily change settings in BIOS. According to statistics, the most popular option in BIOS is the Boot Order, which allows you to change what device will be used as the primary boot device. When the operating system is booting, you need to press the specified key (usually DEL) to enter BIOS. A new window will appear with multiple options grouped in different tabs. You can use the arrow keys on your keyboard to navigate between options and tabs. Some values of essential items can be changed by pressing Page Up/Page Down keys. When all settings you needed have been modified, you need to hit the F10 key to save them and exit BIOS. The main BIOS menu there is a reminder with all keys can use to save changes, discard them, and more. The keys for changing values of parameters are also specified in BIOS. 

How to Update BIOS?

The progress never stands still – new devices are added, fixes and improvements are introduced, so the software must be updated as well. To make your computer understand new devices, you need to update BIOS. For example, when your OS cannot detect a newly connected peripheral it does not mean that something is wrong with – most likely, BIOS just don’t understand what to do with it. If this situation sounds familiar to you, then you should probably check for the latest BIOS update.

But first of all, you need to know what is the current version of your BIOS. To find it out, you need to enter BIOS by pressing DEL when your computer is booting. When you get the version of your BIOS, go to the website of your motherboard manufacturer and look for the latest BIOS update. If there is one (or multiple) just download the most recent one and run it. During the process of installation of new BIOS all the previous data on the BIOS chip will be wiped and then filled with the updated version.

We recommend you to create a backup before installing a BIOS upgrade. There is a chance that BIOS might get corrupted due to an unexpected error and will need a professional to fix it and the backup copy as well. Your bootable DVD may also help with the problem, but it is not guaranteed (depends on how your BIOS reacts to the error or sudden shutdown during the rewriting procedure).

Final words

In the end, we just want to remind you of one important thing: if your PC runs smoothly and detects all devices normally, there is no need to update your BIOS. We also recommend doing it only if you have specific knowledge or ask a professional computer engineer for help. In such scenarios, it is always better safe than sorry.