What is BIOS (Basic Input Output System)? BIOS vs UEFI?

BIOS System


Before our computers turn on and show the familiar interfaces and applications, there's an essential component at work in the background: the BIOS. Often unnoticed and behind the scenes, it plays a critical role in getting our systems up and running. In this blog, we'll take a closer look at BIOS, understanding its importance and how it serves as the backbone of every computer startup. 


Keep reading to understand:

  • What’s a BIOS? 
  • How does BIOS work? 
  • Why is BIOS important? 
  • What is the function of BIOS? 
  • How to update or upgrade your BIOS? 
  • What are the types of BIOS? 
  • What is the difference between BIOS and UEFI? 
  • How to access BIOS?  
  • FAQs 


What’s a BIOS? 

BIOS stands for "Basic Input/Output System." It is a type of firmware used to initialize and test system hardware components and to load an operating system or other software when a computer is turned on. 


How does BIOS work? 

The BIOS is like the computer's built-in instruction manual, saved on the main computer board (motherboard) chip. When the computer turns on, the BIOS quickly checks to ensure everything's in order and working. It looks for boot devices, which are parts that have the critical files the computer needs to start up. After ensuring these parts are okay, the BIOS loads the computer's main system (operating system) from the storage devices like a hard drive into its temporary memory (RAM). 


Why is BIOS important? 

In essence, without the BIOS, a computer couldn't start or function properly. The BIOS is a fundamental computer component responsible for initiating hardware checks, initializing system components, and loading the operating system during startup. It acts as a bridge between the computer's hardware and software, allowing them to communicate efficiently. Moreover, it provides users with system configuration options and introduces critical security features, such as boot protection.  


What is the main function of BIOS? 

  1. POST 
  2. Bootstrap Loader 
  3. BIOS Drivers 
  4. BIOS (CMOS) Setup 


Power-On Self-Test (POST) 

This is the first task the BIOS performs when the computer is turned on. POST checks the hardware components of the computer to ensure they are functioning properly. If any critical component fails this test, the computer might not boot, and you could hear a series of beeps indicating a problem. 


Bootstrap Loader 

After the POST, the BIOS's next task is to initiate the process of loading the operating system. The bootstrap loader searches for the system's operating system in its usual storage location (like a hard drive or SSD) and hands over control to it, allowing the computer to fully start up. 


BIOS Drivers 

These are essential software components within the BIOS that communicate with the computer's hardware, such as the keyboard, mouse, and display. They ensure that the operating system can recognize and interact with the computer's hardware even before any additional drivers are loaded. 


BIOS (CMOS) Setup 

Also known as CMOS setup, this is a configuration menu that allows users to modify system settings. Within the BIOS setup, users can adjust various hardware configurations, set the system clock, manage boot order, and more. It's the interface that users interact with when they want to make changes to how the computer boots or recognizes hardware. 


How to update or upgrade your BIOS? 

BIOS Update (or flashing) 

  • This is the more common procedure. Manufacturers release updates to their BIOS firmware to fix bugs, add compatibility with new hardware, or introduce new features. Users can download these updates from the manufacturer's website and apply them using specific utilities. 
  • Updating, or "flashing," the BIOS requires caution. If the process is interrupted (e.g., due to power loss) or if an incorrect version is used, it can render the computer non-operational. 
  • Some modern motherboards come with dual BIOS chips as fail-safe, so if one BIOS is corrupted during an update, the system can revert to the second, working BIOS. 

BIOS Chip Upgrade 

  • To upgrade the memory on a BIOS chip, one must replace the current chip with a newer, more advanced version. 
  • Some older motherboards, or specialized systems, have BIOS chips that can be physically removed and replaced. This is less common in contemporary systems but was more prevalent in older computers. 
  • If a motherboard's BIOS becomes corrupt and can't be recovered, or if there's a need for a different BIOS version not available through flashing, physically replacing the chip might be an option. However, it requires careful handling and a specific replacement chip.


What are the types of BIOS? 

There are two main types of BIOS:  Legacy BIOS and UEFI 

Legacy BIOS 

Legacy BIOS is the original firmware interface for PCs, bridging the computer's hardware and its operating system. 


UEFI (Unified Extensible Firmware Interface) is the modern successor to Legacy BIOS, designed to improve upon its limitations. UEFI offers a more graphical and user-friendly interface, making it easier for users to navigate and adjust their system settings. 


What is the difference between BIOS and UEFI? 

While traditional BIOS is the older firmware interface, many modern systems use UEFI, a more recent firmware interface standard with more features. UEFI offers a graphical interface, better hardware support, and enhanced security features, among other improvements. Here's a comparison between the two: 

Features/ Aspect  BIOS   UEFI  
Age & Development  Introduced in the late 1970s with the IBM PC. Relatively static features.  Developed in the 2000s to overcome BIOS limitations and support modern PCs. 
Boot Process  Uses the Master Boot Record (MBR) method to manage bootable devices, which has limitations like supporting hard drives only up to 2TB.  Utilizes the GUID Partition Table (GPT) approach, supports hard drives >2TB and can boot from multiple sources. 
Speed & Efficiency  Slower due to sequential hardware initialization.  Faster, as it initializes devices in parallel. Offers "fast boot" options. 
Security  Lacks advanced security features  Has Secure Boot, ensuring only signed/trusted software runs during boot. 
Compatibility & Hardware Support  Supports legacy PC hardware and software  Designed for newer architectures and technologies, with backward compatibility options. 


How do access BIOS?  

To access and configure BIOS settings, users can use the BIOS Setup Utility, which essentially serves as the interface for the BIOS. Unlike operating systems that may require installation, BIOS is pre-installed, offering immediate functionality when the system is powered on. The method to access the BIOS Setup Utility varies based on the specific computer or motherboard brand and model. 


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What does BIOS stand for? 

BIOS stands for Basic Input Output System. 

Is the BIOS software or hardware? 

BIOS is software, but it's stored on a hardware component on the motherboard. 

Where is BIOS stored? 

BIOS is stored on a chip on the motherboard, typically referred to as the BIOS chip or firmware chip. 

What is "Secure Boot" in BIOS settings? 

"Secure Boot" is a feature in BIOS settings that ensures only digitally signed and trusted software, like official operating systems, can run during the computer's startup. It's designed to protect the system from low-level malware attacks and unauthorized operating system installations. 

Is BIOS fully secure? 

BIOS is not fully secure. While BIOS plays a fundamental role in the booting process and system operations, it has been targeted by various types of malwares and exploits over the years. 

Can BIOS settings affect computer performance? 

Yes, certain BIOS settings can influence computer performance. For instance, settings related to CPU clock speeds, RAM timings, or power management can either enhance or limit performance. However, altering these settings without proper knowledge can lead to system instability. 

Is BIOS on motherboard or CPU? 

BIOS is located on a chip on the motherboard, not the CPU. 

Is BIOS in Ram or ROM? 

BIOS is typically stored in a type of ROM (Read-Only Memory) called firmware, often in the form of flash memory. This allows it to be persistent and retain its information even when the power is turned off, but also lets it be updated or "flashed" with new versions. 

Is BIOS the same for all computers? 

No, BIOS is not the same for all computers. While the fundamental purpose of BIOS (to initialize and test the system hardware and load the operating system) remains consistent across computers.