BIOS and Booting Process Explained – Complete Guide for Beginner

BIOS and Booting Process – Complete and Easy Guide for Beginners

Ever wonder what happens inside your computer system when you press the power button?

The Answer is (BIOS and booting process). BIOS (Basic Input/Output System) is firmware that initializes computer hardware and starts the boot process when you power on your PC.

 

Today In this article, we will deeply learn about BIOS and the booting process, also how they work together. This is the most informative topic for students who want to learn deeply about the computer system.

What is BIOS?  

BIOS stands for Basic Input /Output System. BIOS is a type of firmware software that is permanently installed inside a chip on the motherboard of the computer. When we turn on the computer, the very first program that runs is BIOS, not Windows or Linux, which are operating systems.

Basically, BIOS acts as a bridge between hardware and software. BIOS first checks all the Computer Hardware Components before starting the computer system.

In simple words, we can say:

BIOS tells the computer about the hardware installed in the computer system and how to start the operating system. BIOS is permanently attached with motherboard, which means if Windows is deleted and the hard disk is formatted, it does not affect the BIOS.

That is why BIOS is already present when we install a new operating system.   

Role of BIOS

What happens when we turn on the computer?

• Power supply becomes active
• Electricity reaches the motherboard
• BIOS gets activated
• BIOS performs the POST test
• BIOS searches for a boot device
• The bootloader is loaded into RAM
• Operating System starts

This is the all process of BIOS.

Some functions of BIOS

Basically, BIOS has four functions, which are deeply explained for the beginner to understand the process:

Hardware Initialization

Whenever a computer receives power, the very first system that takes responsibility is the BIOS. BIOS acts like a hidden technician that wakes up all the hardware devices one by one in the background:

• It initializes the processor
• Tests the RAM
• Activates the keyboard and mouse
• Prepares the hard disk or SSD
• Checks the graphics card and USB ports

Until the BIOS properly detects all these components, the operating system cannot use them.

POST

POST (Power On Self-Test). POST is basically a quick medical check-up for the system, in which it verifies whether the:

• RAM is working correctly
• The keyboard is properly connected
• The display is responding
• The processor is overheated or not
• The storage devices are being detected

If POST finds any issue, an error message shows on screen, and sometimes the booting process can stop.

On the other hand, if everything is working, then the BIOS moves to the next process.

Starting the boot loading process

This process is called boot loading. First of all, BIOS searches for devices that are bootable, then reads their boot sector, then loads that bootloader into RAM, and transfers all the control to the operating system.

Boot order is very important because BIOS wants to check devices in a specific sequence.

BIOS Setup utility

BIOS setup utility is another powerful feature that is open at start-up by pressing keys like Del, F2, F10, Esc, etc.

In this Setup, we can manage the basic system settings.

• Set date and time
• Changing boot priorities
• Adding system passwords
• Enabling or disabling virtualization
• Turning USB ports on or off
• Controlling fan speed and temperature

This menu is like the control room of the computer, from where the user can configure all core system operations.

After the BIOS finishes its work, the Operating System, like Windows, Linux, or Mac OS, starts loading into memory.

What is the booting process?

When we turn on a computer from its off state and the operating system starts loading, it’s called the booting process.
When our operating systems, like Windows, Linux, and Mac, are fully loaded into our RAM, the computer becomes ready to use, and then it's called booting.
If the booting process is not successful, the computer remains useless for the user.

Cold boot (hard boot)

The computer system has been powered off for the last two days, and now we’re about to turn on the computer using the power button, which is called a cold boot.

Warm boot (soft boot)

When we are using our computer, and we want to restart it, then it is called a warm boot.

Complete Booting Process Step-by-Step Guide for Beginners

The booting process follows several steps given below:

• Step 1: The user presses the power button.
• Step 2: The power supply sends electricity to the motherboard.
• Step 3: BIOS activated.
• Step 4: BIOS performs POST test.
• Step 5: BIOS searches for boot devices.
• Step 6: The boot loader loads into RAM.
• Step 7: The operating system loads into RAM.
• Step 8: The user interface appears on the screen.
• Step 9: The user starts using the computer system.

This full setup is called the booting process.

If you want to know how Windows works after the boot process, you can explore Windows Internals in depth.

Interview questions to remember

BIOS stand for?

Answer:

BIOS stands for Basic Input/ Output System. It is firmware that helps start your computer and initializes all the essential hardware components.

Storage place of BIOS?

Answer:

BIOS is stored on the motherboard, which means it does not affect the system even if it is turned off.

What’s the main purpose of bios?

Answer:

BIOS stands for (Basic Input Output System). BIOS is a type of firmware software that is permanently installed inside a chip on the motherboard of the computer

What is Post?

Answer:

POST (Power On Self-Test). POST is basically a quick medical check-up for the system

Difference btw Cold boot vs Warm boot?

Answer:

Cold boot: The computer system has been powered off for the last two days, and now we’re about to turn on the computer using the power button, which is called a cold boot.

Warm boot: When we are using our computer, and we want to restart it, then it is called a warm boot.

How to access BIOS settings in pc?

Answer:

During the start-up process, you can press keys like F2, F10, or Del for accessing BIOS.

Role of Bios to starting the operating system?

Answer:

• Power supply becomes active
• Electricity reaches the motherboard
• BIOS gets activated
• BIOS performs the POST test
• BIOS searches for a boot device
• The bootloader is loaded into RAM
• Operating System starts

Can we change the boot sequence of the BIOS?

Answer:

To change the boot order, we can:

• Enter bios
• Go to the boot menu
• Set device priority

Step-by-step process from Power ON to OS loaded process?

Answer:

• Power starts supplying.
• BIOS runs the POST check.
• BIOS locates the boot device.
• The bootloader loads the operating system.
• Kernel initializes the hardware.
• The operating system starts and loads the GUI/login screen.

Conclusion

Both BIOS and the booting process are the most important parts of a computer system. Without a BIOS, a computer cannot start properly. BIOS quickly performs some of the most critical tasks, primarily hardware preparation, which is essential for operations, ensuring that the system is ready to load the operating system.

The booting process is equally essential; it acts as a bridge between hardware components and software operation, starting from when power flows into the motherboard to when the desktop appears on the screen. Each step follows a precise and carefully designed sequence. In simple words, buzz is the most important role of a computer system.

 

 

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