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Table of contents
What is BIOS?
History of BIOS
What is included in a BIOS?
Functions of BIOS
Types of BIOS
Difference between BIOS and UEFI?
BIOS Setup Utility
BIOS Updates
BIOS Availability
BIOS Security
BIOS Manufacturers
Troubleshooting BIOS Issues
Frequently Asked Questions
What is BIOS and why is it needed?
Types of BIOS
Why is it called BIOS?
Last Updated: Mar 27, 2024

What is BIOS (Basic Input/Output System)?

Author Harsh Singh
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The BIOS stands for Basic Input Output System. It is a critical component of modern computer systems, yet it is often overlooked or misunderstood by many users. 

It is a firmware that acts as the interface between the hardware components and the operating system, facilitating communication and controlling various system functions.

Basic Input Output System

In this article, we will explore the BIOS in depth, covering its history, purpose, features, and how it has evolved over time.

Also see,  Open Source Operating System

What is BIOS?

BIOS stands for Basic Input/Output System. It is a firmware program that is stored on a chip on the motherboard of a computer. BIOS is responsible for initializing the hardware components of the computer and loading the operating system. It also provides a way for users to configure the computer's hardware and settings.

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History of BIOS

The concept of BIOS dates back to the early days of computing when computers were large, mainframe systems.

In those days, computers relied on paper tape or punch cards to input data, and the output was usually in the form of printed reports. 

The BIOS, as we know it today, was developed in the 1970s by IBM for its IBM PC, which was released in 1981. 

  • The original BIOS was a simple set of instructions stored in a read-only memory (ROM) chip that initialized the hardware and provided basic input and output functions
  • Over time, the BIOS evolved to include more advanced features like support for hard drives and other peripherals. 
  • It also became more customizable, allowing users to modify various settings like system clock speed and boot order.
  • In the 1990s, a new type of firmware called UEFI (Unified Extensible Firmware Interface) was developed to replace the aging BIOS. 
  • UEFI is a more modern and flexible system that allows for faster boot times and more advanced features like secure boot and network booting.

What is included in a BIOS?

Below are the common things that are included in a BIOS:

  • Boot loader: responsible for loading the operating system from the hard drive or other storage device
  • Device drivers: responsible for allowing the computer to communicate with the hardware devices, such as the keyboard, mouse, and hard drive
  • CMOS setup: CMOS is a program which allows users to change the BIOS settings like security settings, date and time, etc
  • Power-on self-test (POST):  It is a diagnostic test that the BIOS runs when the computer is turned on to check if the hardware components are working properly
  • ACPI tables: These tables contain information about the computer's power management features
  • Firmware updates: These are updates to the BIOS firmware that can fix bugs or add new features

Functions of BIOS

The BIOS has several key features that make it an essential part of a computer system:

  • Power-On Self-Test (POST): During the boot process, the BIOS performs a series of tests on the hardware components, such as the CPU, memory, and storage devices, to check if they are functioning properly. If any issues are detected, the BIOS may display error messages or emit beep codes to alert the user.
  • System Configuration: The BIOS allows users to configure various system settings, such as the boot order of devices, date and time, and hardware parameters. These settings can be accessed and modified through the BIOS setup utility, which is typically accessed by pressing a specific key during the boot process, such as F2 or Del.
  • Device Initialization: The BIOS initializes all the hardware components of the computer, including the CPU, memory, storage devices, and peripheral devices, such as keyboard and mouse. It provides the necessary instructions for these devices to start functioning and communicate with the operating system.
  • Boot Loader: The BIOS contains a boot loader, which is a small program that loads the operating system into memory and starts its execution. The boot loader reads the boot sector of the storage device, which contains the initial instructions for the operating system to start loading.
  • Firmware Updates: The BIOS can be updated with new firmware to fix bugs, improve compatibility, and add new features. Firmware updates are typically provided by the motherboard manufacturer and can be installed using a utility provided by the manufacturer.

Also see, Parallel Operating System

Types of BIOS

There are two types of BIOS discussed below: 

Types of BIOS
  • Traditional BIOS: Refers to the original BIOS developed by IBM, which used a simple set of instructions stored in a ROM chip and was commonly used in older computer systems.
  • UEFI (Unified Extensible Firmware Interface) and EFI (Extensible Firmware Interface): Refers to modern BIOS types that offer advanced features, such as larger storage support, faster boot times, graphical user interfaces (GUI), and improved security.

Difference between BIOS and UEFI?

Below is a table which summarizes the key differences between BIOS and UEFI:

Architecture 16-bit 32-bit or 64-bit
Storage ROM chip Flash memory chip
Bootable drive size limit 2.2TB 9 zettabytes
User interface Text-based Graphical
Security features None Secure Boot
Boot time Slow Fast
Flexibility Limited More flexible

BIOS Setup Utility

  • Accessing BIOS Setup Utility: Explains the process of accessing the BIOS setup utility during the boot process through specific keys or buttons
  • Common BIOS Settings: Discusses commonly available BIOS settings, such as boot order, date and time, hardware parameters, security settings, and advanced settings, which can be configured using the BIOS setup utility

BIOS Updates

  • Importance of BIOS Updates: Highlights the significance of keeping the BIOS up-to-date to ensure optimal performance, compatibility, and security
  • Methods for Updating BIOS: Discusses different methods for updating the BIOS, including using the manufacturer's utility, flashing the BIOS, and precautions to be taken during the update process

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BIOS Availability

The BIOS is stored on a small, read-only memory (ROM) chip on the motherboard of a computer. This chip is usually located near the processor. The BIOS is also sometimes stored on a flash memory chip, which can be updated more easily.

BIOS Security

The BIOS is an important part of any computer security system because it is responsible for initializing the hardware components of the computer and loading the operating system. If the BIOS is compromised, then a hacker can gain access to the computer and install malware or bugs.

In order to protect the BIOS, keep the BIOS firmware up to date. BIOS updates often include security patches that fix vulnerabilities that could be exploited by attackers. It is also important to set a strong BIOS password. This will prevent unauthorized users from accessing the BIOS settings and making changes that could compromise the security of the computer.

BIOS Manufacturers

There are many different companies that manufacture BIOSes. Some of the most popular BIOS manufacturers include:

  • American Megatrends (AMI)
  • Asus
  • Dell
  • Insyde Software
  • Phoenix Technologies
  • Ricoh

Troubleshooting BIOS Issues

  • Common BIOS Errors: Covers common errors or issues that users may encounter with the BIOS, such as boot failures, error messages, or configuration problems
  • Troubleshooting Steps: Provides general troubleshooting steps for resolving BIOS-related issues, including resetting BIOS settings, updating BIOS firmware, and seeking manufacturer support for assistance

Also see, fcfs scheduling algorithm

Frequently Asked Questions

What is BIOS and why is it needed?

BIOS basically stands for Basic Input/Output System and is a firmware program which is stored on a chip on the motherboard of a computer. BIOS main job is to initialize the hardware components of the computer and load the operating system.

Types of BIOS

Two main types of BIOS that are legacy BIOS which is an a16-bit program that is stored on a ROM chip, and UEFI BIOS, which is a 32-bit or 64-bit program that is stored on a flash memory chip

Why is it called BIOS?

The name BIOS comes from the words "basic input/output system". This is because BIOS is responsible for initializing the basic input/output devices of the computer, such as the keyboard, mouse, and hard drive.


In this blog, we discussed the crucial role of BIOS in the boot process, hardware initialization, and system configuration in modern computer systems. We also looked at the potential future developments and advancements in BIOS technology that could help in enhancing it. 

If you want to learn more about BIOS, we recommend you to go through this article: What is UEFI and How it is different from BIOS?

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