"BIOS vs UEFI: The Complete Guide to Modern Firmware Differences"
Welcome to Cyber Knowledge Hub!
Hi friends!
Have you ever turned on your computer and thought, “What happens before Windows starts?”
Today we will learn the difference between BIOS and UEFI in a very easy way.
No hard computer words, only simple examples.
You can also ask me questions in the comments if you do not understand something.
So, let’s start and learn how your computer boots up!
1.First, we will learn what BIOS is and how it works?
Basic Input Output System
• BIOS is a small program inside the computer. It starts when you turn on the computer. It checks the hardware like keyboard, mouse, and hard drive, then it helps to start the operating system like Windows or Linux.
The BIOS screen is simple and text-based. When you turn on the computer and press a key like F2, DEL, or Esc, a blue or black screen appears with menus. You move through the menus using the keyboard. In BIOS, you can set the date and time, change the boot order, see hardware details, and set security options.
BIOS is stored in a small ROM chip on the motherboard. This ROM chip gets power from a small battery called the CMOS battery. Inside the ROM, there are instructions to start the computer, settings for date and time, boot order, and basic hardware information.
•I want to show you what a ROM OR CMOS battery looks like through a photo.
The CMOS battery is on the left side, and the BIOS chip is on the right side. I showed you this through the image so that when you see a motherboard for the first time, you can easily identify where the BIOS and CMOS battery are located on it.
The CMOS battery gives power to the basic settings on the motherboard when the computer is turned off or unplugged. This battery:
Keeps the date and time running.
Remembers the BIOS settings (like boot order and hardware setup).
•If the CMOS battery fails.
•The computer’s date and time will reset every time you turn it on.
•BIOS settings (like boot order or custom changes) will go back to default, so your changes won’t be saved.
•Sometimes, the computer may have trouble starting or show error messages.
•That’s why the CMOS battery is important for the system to work properly.
• If you have made some wrong changes in the BIOS settings, there is no need to worry. You can fix it yourself.
• There are three ways to fix this.
1. Reset BIOS through BIOS Menu:
•Restart the computer and press the key to enter BIOS (like F2, Del, or Esc).
•Find the option called "Load Setup Defaults" or "Restore Defaults."
•Select this option to reset settings to default.
•Save the changes and exit BIOS.
2. Reset BIOS by Removing CMOS Battery:
•Turn off the computer and unplug it.
•Carefully remove the CMOS battery from the motherboard.
•Keep the battery out for 5–10 minutes to clear BIOS settings.
•Put the battery back and start the computer.
3.Reset BIOS using Jumper:
•Find the CMOS reset jumper on the motherboard (usually a 3-pin connector).
•Check the motherboard manual and move the jumper to the reset position for a few seconds.
•Move the jumper back to the original position.
•Restart the computer.
•Now, we want to explain to you what UEFI is.•
UEFI (Unified Extensible Firmware Interface) is modern software that acts as a bridge between your computer’s hardware and operating system. It is an updated version of BIOS.
• Now, we will explain to you the details about BIOS vs UEFI. Is that okay?
• So, I have shown you how a text-based interface looks and how a graphical interface looks.
•So, let's talk about the differences between BIOS and UEFI, and I will tell you which operating systems BIOS supports and which ones UEFI supports.
•Here are some key features of BIOS:
•Basic Input/Output System that starts the computer hardware.
•Uses a text-based interface.
•Runs the Power-On Self-Test (POST) to check hardware.
•Power-On Self Test (POST) is a process that checks if all hardware like the hard disk and other parts are working properly when the computer starts. If everything is okay, then the boot process continues.
•Supports booting from MBR (Master Boot Record) disks.
•Master Boot Record (MBR) is a special type of data stored in the first part of a hard drive.
• It is responsible for
• Tell the computer where to start the operating system on the hard drive.
• Store the partition table, which shows how the hard drive is divided into parts for different uses.
•In simple words, MBR is a small program that helps the computer start the boot process.
• MBR (Master Boot Record) allows you to create up to 4 primary partitions on a hard drive.
• If you need more partitions, one of these primary partitions can be made an extended partition, which can hold multiple logical partitions inside it.
• So, in total:
• 4 primary partitions, or
• 3 primary partitions + 1 extended partition (which can contain many logical partitions).
•Limited support for large hard drives (up to 2 TB).
•Slower boot time compared to UEFI.
•Limited security features.
• BIOS has some basic security features like:
•Password Protection: You can set a password to stop others from changing BIOS settings.
•Boot Device Control: You can choose which device the computer should start from (like hard drive, USB, or CD).
•Basic Hardware Checks: BIOS does simple checks to make sure hardware is working.
•But BIOS does not have advanced security features like:
•Secure Boot to block harmful software
•Encryption support
•Network security features
That’s why modern systems use UEFI, which has better security.
•Not easily extensible or upgradable.
•Here are the key features of UEFI:
•Faster Booting: Starts your computer faster than BIOS.
•Secure Boot: Protects your system from malware during startup.
•Supports Large Drives: Can handle hard drives larger than 2 TB .
•UEFI supports storage sizes up to 9.4 zettabytes (ZB).
•Graphical Interface: Has a user-friendly interface with mouse support.
•Network Booting: Can boot your system over a network (PXE boot).
• PXE Boot means Preboot Execution Environment.
•It is a way for a computer to start (boot) using files from a network instead of a local hard drive or USB.
•How PXE Boot works:
1. When the computer starts, it checks if PXE boot is enabled in BIOS/UEFI.
2. If yes, the computer connects to a special server on the network.
3. The server sends a small program called a bootloader to the computer.
4. The bootloader downloads the operating system or installation files from the network.
5. The computer then starts running the operating system without using local storage.
•Benefits of PXE Boot:
You can install the same operating system on many computers easily.
It helps in setting up and fixing computers remotely.
It avoids problems with local storage.
•Extensible: Allows adding new features and drivers easily.
•Better Partition Support: Uses GPT which supports more partitions than BIOS’s MBR.
• GPT (GUID Partition Table) is a modern system that organizes hard drives into parts called partitions.
•What GPT does:
• Divides a hard drive into multiple partitions to store different data or operating systems.
• Supports very large hard drives (more than 2 TB), unlike the old MBR system.
• Gives each partition a unique ID (called GUID) so the system can easily recognize them.
• Allows many more partitions (MBR allows only 4 primary, GPT allows 128 or more).
• Saves partition data in multiple places to help recover if something gets damaged.
• In simple words, GPT helps organize your hard drive better and use its full size efficiently.
•More Secure: Offers advanced security options to protect your system.
• MBR (Master Boot Record) mostly supports these operating systems:
•Windows:
•Windows XP (32-bit and 64-bit)
•Windows Vista
•Windows 7
•Windows 8 and 10 (but only in Legacy BIOS mode, not UEFI mode)
• GPT (GUID Partition Table) supports most modern operating systems, including:
•Windows:
•Windows Vista (64-bit) and later versions like Windows 7, 8, 10, and 11 (especially in UEFI mode).
Thank you for taking the time to learn about BIOS, UEFI, and disk partitioning. Understanding these fundamental concepts helps you make better decisions for your computer’s performance and security. If you have any questions or want to explore more topics, feel free to reach out. Keep learning and stay curious!
Thank you for reading!
— Writer Kishan
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