Know All About BIOS | Types of BIOS and How to Use It

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In these modern days of technology, you get a personal computer for many reasons. So, you most probably have heard the terms BIOS or UEFI. But this sometimes confuses users like you about the meaning and functions of them. What is BIOS, or UEFI, or types of BIOS? To know all the answers to your question, read the full article. You will know about BIOS and the types of BIOS and its functions and how to access and customize it.

Types of Bios

What is BIOS

If you got a computer, then you have most probably heard of these terms BIOS. But what does BIOS stand for? BIOS means your computer’s Basic Input / Output System. But what does it means? You may know that your personal computer has a microprocessor that does most of the important things on your PC. BIOS is a program that is used by the microprocessor of your computer to start the computer after it is turned on.

But a question may arise in your mind that you didn’t install BIOS on your computer when you bought it. It generally comes with you when you buy a computer. Your computer’s Operating System (OS) can be pre-installed or not. But the BIOS is a program that is preinstalled on an Erasable Programmable Read-Only Memory (EPROM). It manages the data flow between the computer’s OS and other devices like hard disk, keyboard, processor, mouse, etc.

You already know that BIOS is the abbreviation of the Basic Input / Output System. From the name, it is clearly seen that it is one type of program that is related to the input, or output. But what does this actually mean? BIOS is a pre-installed program that is concerned with the data flow between your operating system and devices like keyboard, mouse, hard drives, etc. The microprocessor uses it first to start your computer system when you turn on your computer.

What is BIOS

Where Does BIOS Reside?

After bringing your computer home, you also brought BIOS within it. It is a pre-installed program that is used by the microprocessor to start the computer system. When you turn on your computer, the microprocessor access the BIOS so that it can start the operating system. You may have installed an operating system like Windows or Linux on your computer. Which is generally installed on the hard drive.

In the case of BIOS, it is not like that because the hard drives cannot be accessed at once when you turn on your PC. The microprocessor needs to access it to give control of the input/output to the BIOS. So, it is installed on an EPROM that stands for Erasable Programmable Read-Only Memory. The microprocessor passes the control to the BIOS which is always located in EPROM.

What is BIOS

What Does BIOS Actually Do?

You already have got a little idea about the function of the BIOS on your computer. From the name, it is clear that it controls the basic input/output system of your computer. When you turn on your computer, the microprocessor gives control to the BIOS so that it can start the computer system.

When BIOS starts (generally after turning on the computer), it determines whether all other components of your computer are currently working or in the correct places. If there is no error, then the BIOS loads the Operating System of your computer. So, the OS does not need to check any hardware error. As you know that the OS is also a software program, so, it needs to be loaded on the RAM (Random Access Memory) before it can function. It is done by the BIOS.

You may have heard the term ‘system BIOS’. But what is system BIOS and why is it called system BIOS? When you turn on your computer, the microprocessor of your computer access the BIOS from the EPROM and gives control of the input/output to the BIOS. It is started before your operating system is active. It is also called the System BIOS because it is responsible for the operating system being loaded in the RAM. So, it can be said that it acts as an intermediate program between the operating system and the hardware of your computer.

Just like system BIOS, the BIOS of your computer is also called as lead BIOS. But what is load BIOS? The operating system of your computer is the main thing with which you interact most of the time. But it is nothing but a software program which makes sure that all other application programs like MS Word, Adobe Photoshop, Chrome, etc can work perfectly without directly contacting the hardware.

So, at first, the OS needs to be loaded on the RAM so that it can perform. After turning on the computer, the BIOS does this loading of the OS in the RAM.

The functions of BIOS is very crucial in starting your computer system. The BIOS resides on the EPROM or your computer. After turning on the computer, its job started.

  1. Hardware Error Checking: Before loading the operating system, it checks if there is an error in the hardware or whether the hardware is locating at the exact places. So, the operating system doesn’t need to check this.
  2. Bootstrap Loader: After error checking is finished, it locates the operating system. If a suitable operating is found, the BIOS loads it in the RAM and passes controls to it.
  3. Controls Hardware: There are BIOS drivers that give your computer control over the hardware.
  4. BIOS Setup: There are some programs that can configure hardware or system settings like your computer’s password, or date/time.
  5. Freeing OS and software: If there is no BIOS, then the operating system and the other software need to know the exact details of the hardware and the location of them. But for BIOS, the OS and software don’t need to deal with this.

How to Access the BIOS

You generally don’t need to do this. But you can access the BIOS settings and do some changes. So, it is good to know how to access it. As it works with the input/output device, it doesn’t need to be changed frequently. If a device detail is changed or if you want to make a change, you have to access the BIOS.

After turning on the computer, you will see that your PC is booting. Before it loads the Operating System, press ‘Delete’ or F2 key. BIOS entering option may vary from computer to computer. Check before entering the BIOS.

How to Access the BIOS

Types of BIOS

There are two types of BIOS:

  1. UEFI BIOS: The UEFI or Unified Extensible Firmware Interface has ability to 2.2TB or larger handle drives. Earlier, Intel PCs used Legacy BIOS, but they are moving toward UEFI firmware.
  2. Legacy BIOS: The Legacy BIOS or Basic Input/Output System is used in older motherboards. This BIOS can not recognize or handle larger than 2 TB.


If you have recently bought a computer, then most probably you will see UEFI instead of BIOS. But what is UEFI and what’s the difference between them? Actually, it is not that easy to differentiate BIOS and UEFI as they almost do the same thing. UEFI stands for Unified Extensible Firmware Interface. Same as BIOS, UEFI acts as an intermediate program between the operating system and the hardware.

UEFI is a framework that can be extensively customized. It provides more features than BIOS. It doesn’t need a bootloader or separate program in order to load the OS. It provides native support GPT that can manage hard drives which can be exceeded two Terabytes. But BIOS cannot offer this.


After reading the whole article, we hope, you know all the things about BIOS and its functionalities. From now on, different types of BIOS, or BIOS vs UEFI, these terms won’t bother you much we hope.

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