Booting Process, BIOS, UEFI and POST: Types of Booting and System Startup Explained for SSC Computer Awareness

Booting is the process of starting a computer and loading the operating system into memory. Questions such as “What is a cold boot?” and “Which program runs first when the computer starts?” are common in SSC computer awareness. This guide on booting process and BIOS for SSC explains the steps of booting, the types of booting, BIOS, UEFI and CMOS, with practice questions and FAQs.

What Is Booting?

Booting is the process of starting the computer, testing the hardware and loading the operating system from the disk into the main memory (RAM). The word comes from “bootstrap”, meaning to start from nothing.

Steps of the Booting Process

1. Power on: the power supply gives power and the CPU starts executing the code stored in the ROM (BIOS or UEFI firmware).
2. POST (Power-On Self Test): the BIOS checks the hardware such as RAM, keyboard and disk. Beeps or messages report any fault.
3. Bootstrap loader: the BIOS finds the boot device and loads the bootstrap program from the boot sector (Master Boot Record).
4. Loading the OS kernel: the boot loader loads the operating system into RAM.
5. OS ready: the OS starts services and drivers and shows the login screen or desktop.

Types of Booting

BIOS

• BIOS stands for Basic Input Output System.
• It is a firmware stored in a ROM or flash chip on the motherboard.
• It is the first program that runs when the computer is switched on.
• It performs the POST, finds the boot device and loads the bootstrap loader.
• It provides the setup utility in which the boot order, date and time can be set.

UEFI

CMOS

CMOS (Complementary Metal Oxide Semiconductor) is a small memory chip on the motherboard that stores the BIOS settings such as the date, time and boot order. It is powered by a small battery, so that settings are kept even when the computer is off. If the CMOS battery fails, the computer may lose the date and time.

Booting-Related Terms

Important Facts

• The POST is run by the BIOS before loading the OS.
• The first program that runs at start-up is the BIOS (firmware).
• A warm boot is also called a restart and a cold boot is also called a hard boot.
• The booting process loads the OS into the RAM because RAM is the working memory.
• If the POST finds an error, the computer may give beep sounds.

Quick Tips

• Learn the steps in order: power on, POST, bootstrap, OS load.
• Remember cold boot means from a switched-off state.
• Learn the full forms BIOS, UEFI and POST.
• Remember that CMOS keeps the settings.

Quick Revision Points

• Booting loads the OS into RAM.
• POST tests the hardware at start-up.
• BIOS is a firmware stored in ROM or flash.
• Cold boot starts from a switched-off state; warm boot is a restart.
• UEFI is the newer replacement for BIOS.

Practice Questions With Answers

1. What is the full form of BIOS?
   Answer: Basic Input Output System
2. What does POST stand for?
   Answer: Power-On Self Test
3. What is booting a computer from a switched-off state called?
   Answer: Cold boot
4. What is restarting a computer without switching it off called?
   Answer: Warm boot
5. Which chip stores the BIOS settings with a battery?
   Answer: CMOS
6. What is the first program that runs when a computer starts?
   Answer: BIOS
7. Where is the OS loaded in the booting process?
   Answer: RAM
8. What is the full form of UEFI?
   Answer: Unified Extensible Firmware Interface
9. Which mode starts the OS with only basic drivers?
   Answer: Safe mode
10. What is a small program that loads the OS called?
    Answer: Bootstrap loader

How to Practise This Chapter

Practise 10 questions every day and write the steps on paper. Then attempt timed sets from our practice papers and the previous year papers page. See all topics on the Computer Knowledge notes page, read the previous topic CPU and Microprocessor and the next topic Logic Gates and Boolean Algebra.

Frequently Asked Questions

What is booting?

The process of starting a computer and loading the operating system into memory.

What is POST?

The Power-On Self Test, run by the BIOS to check hardware at start-up.

What is a cold boot?

Starting the computer from the switched-off state.

What is a warm boot?

Restarting the computer while it is on.

What is BIOS?

The Basic Input Output System, a firmware that starts the computer and loads the bootstrap program.

What is the difference between BIOS and UEFI?

UEFI is the newer firmware with support for larger disks, a graphical interface and secure boot.

What is CMOS?

A memory chip that stores BIOS settings, powered by a battery.

What is the bootstrap loader?

A small program that loads the operating system from the disk into memory.

What is safe mode?

A start-up mode with only the essential drivers used for troubleshooting.

Where is the BIOS stored?

In a ROM or flash memory chip on the motherboard.

Is booting asked in SSC?

Yes. Booting, BIOS and POST are common in computer awareness.

What is the boot sector?

The first sector of a disk that contains the boot loader.