What is BIOS (Basic Input/Output System)?

What is BIOS?

BIOS, which stands for Basic Input/Output System, is a fundamental component of a computer system. It is firmware that is stored on a chip on the computer's motherboard. The BIOS provides the necessary instructions for the computer to start up and initialize hardware components before the operating system takes over. The primary function of the BIOS is to perform the Power-On Self-Test (POST), which is a series of diagnostic tests to check the hardware components of the computer. These tests ensure that the system is functioning correctly and can proceed with the booting process. If any errors are detected during the POST, the BIOS may display error messages or emit audible beeps to alert the user. In addition to the POST, the BIOS also contains configuration settings that control various aspects of the computer's hardware. These settings can be accessed and modified through a user interface called the BIOS Setup Utility. The utility allows users to configure parameters such as the boot order of devices, system time and date, CPU settings, and other hardware-specific options. During the boot process, the BIOS loads the operating system from the computer's storage devices, such as the hard drive or SSD, into the computer's memory. Once the operating system is loaded, the BIOS hands over control to the operating system, which then takes charge of managing the hardware and software resources. While the traditional BIOS has been the standard for many years, modern computer systems are now transitioning to a newer firmware called Unified Extensible Firmware Interface (UEFI). UEFI offers more advanced features, improved security, and a graphical user interface for the BIOS Setup Utility. However, the basic principles and functions of the BIOS remain the same.   In summary, the BIOS is a critical component of a computer system that provides the necessary instructions for the system to start up, performs hardware diagnostics, and allows users to configure hardware settings. It acts as a bridge between the hardware and the operating system, ensuring a smooth and successful boot process.  

Types of BIOS

There are different types of basic input-output systems (BIOS) available, which include: Legacy BIOS: Also known as traditional BIOS, this was the original type of BIOS used in IBM-compatible personal computers. It provides basic hardware initialization and boot functions. UEFI (Unified Extensible Firmware Interface): UEFI is a modern replacement for Legacy BIOS. It offers more advanced features and a graphical user interface (GUI). UEFI supports larger hard drives, faster boot times, and secure boot functionality. Coreboot: Coreboot is an open-source firmware project that aims to create a lightweight and customizable BIOS replacement. It is designed to be more flexible and allow for faster boot times. Open Firmware: Open Firmware is a standardized firmware interface used primarily in Apple Macintosh computers and some other systems. It provides a platform-independent firmware environment with a Fourth-based programming language. EFI (Extensible Firmware Interface): EFI is an earlier version of UEFI. It was developed by Intel and introduced in the late 1990s. UEFI evolved from EFI and incorporated additional features and improvements. Proprietary BIOS: Some computer manufacturers develop their own proprietary BIOS implementations tailored to their specific hardware platforms. These BIOS versions may have unique features or configurations specific to the manufacturer's products.

Figure 1 BIOS UEFI has replaced Legacy BIOS as the primary type of BIOS used in modern computers. It provides improved functionality, security, and compatibility with modern hardware and operating systems.

Where BIOS is Stored?

BIOS is stored on a chip called BIOS chip on the motherboard of modern computers. It is a non-volatile memory chip that contains firmware for booting up and initializing hardware components. The BIOS chip is typically a non-volatile memory chip, meaning that it retains its data even when the computer is powered off. It is commonly a Read-Only Memory (ROM) or Electrically Erasable Programmable Read-Only Memory (EEPROM) chip. The ROM BIOS chip contains the firmware that provides the initial instructions to the computer during the boot process. The BIOS chip is usually located near the edge of the motherboard and is identified by its distinctive shape and markings. It is connected to the motherboard through a series of pins or small connectors. The chip itself is protected by a small, removable cover or a metal heat sink to prevent damage from static electricity or excessive heat. It's important to note that some modern computer systems, especially those that use UEFI (Unified Extensible Firmware Interface) instead of traditional BIOS, may store the firmware differently. UEFI firmware is typically stored in flash memory chips, which can be updated or reprogrammed with new firmware versions. These flash memory chips are also often integrated into the motherboard.

Figure 2 ROM

How does BIOS Work?

Before the operating system gains control, the BIOS is in charge of starting up and setting up hardware components. It has a critical role in the computer's startup process and enables communication between the software and hardware components. Here is a simplified explanation of how BIOS works: Power-On Self-Test (POST): When you turn on your computer, the BIOS initiates a Power-On Self-Test. This process checks the essential hardware components, such as the CPU, memory, storage devices, and graphics card, to ensure they are functioning correctly. If any issues are detected, the BIOS will typically emit a series of beep codes or display an error message. Boot Device Selection: After the POST, the BIOS determines the boot device from which the operating system will be loaded. The boot device can be a hard drive, solid-state drive (SSD), optical drive, or USB drive. The BIOS checks the boot order specified in its settings, known as the CMOS (Complementary Metal-Oxide-Semiconductor) configuration, to determine the priority of boot devices. It then attempts to load the operating system from the highest-priority boot device. MBR/GPT and Bootloader: Once the boot device is identified, the BIOS reads the Master Boot Record (MBR) or the GUID Partition Table (GPT) from the specified boot device. The MBR/GPT contains the bootloader, which is a small program responsible for loading the operating system. The BIOS transfers control to the bootloader by executing the code stored in the MBR/GPT. Handing Over Control to the Operating System: The bootloader locates the operating system's kernel and hands over control to it. At this point, the BIOS has completed its tasks, and the operating system takes over the control of the computer.   Traditional BIOS has been replaced by UEFI, which provides a more modern and flexible interface with improved security and additional features. However, the basic purpose of initializing the system and loading the operating system remains the same.

Will BIOS Boot without CPU?

Figure 3  CPU The Basic Input/Output System (BIOS) cannot initiate booting in the absence of a Central Processing Unit (CPU). The CPU is a vital part of a computer that carries out instructions, and computations, and manages the system's operations. During the boot process, the BIOS performs a Power-On Self-Test (POST) to ensure that all the hardware components, including the CPU, are functioning correctly. If the CPU is not present or not functioning, the POST will fail, and the system will not be able to proceed with the boot process. The CPU is responsible for executing the initial instructions stored in the BIOS chip, which include the instructions to initialize hardware devices, load the operating system, and handle other critical functions. Without a CPU, the computer lacks the core processing power required to perform these tasks. In summary, the CPU is an essential component for the proper functioning of a computer system, and the BIOS cannot boot without it. The CPU plays a crucial role in executing instructions and controlling the overall operation of the system during the boot process and throughout the computer's operation.  

BIOS vs CMOS

BIOS and CMOS (Complementary Metal-Oxide-Semiconductor) are closely related but distinct components in a computer system. Let's explore the differences between BIOS and CMOS. The BIOS is firmware that is stored on a chip (usually a ROM or EEPROM) on the computer's motherboard. It contains the fundamental instructions and settings that the computer needs to boot up and initialize hardware components before the operating system takes over. The BIOS performs tasks such as the Power-On Self-Test (POST), which checks the hardware for any issues, and then loads the operating system. The BIOS provides a basic interface between the computer's hardware and software. It handles tasks such as managing memory, detecting and configuring hardware devices, and providing a set of system functions for the operating system to utilize. The BIOS settings can be accessed and modified through a setup utility typically accessed by pressing a specific key during boot-up (such as F2 or Del). CMOS, on the other hand, refers to a specific technology used for constructing integrated circuits. In the context of computers, CMOS refers to a small amount of volatile memory that stores the system's configuration settings. This memory is powered by a small battery on the motherboard, even when the computer is turned off, to retain the settings.

Figure 4 CMOS The CMOS memory stores information such as the system date and time, hardware settings (e.g., boot device priority, CPU settings), and other user-configurable options. The BIOS reads these settings from the CMOS memory during the boot process and applies them accordingly. Users can access and modify the CMOS settings through the BIOS setup utility. In summary, the BIOS is firmware that provides the fundamental instructions and interfaces between hardware and software, while CMOS refers to a small volatile memory that stores system configuration settings. The BIOS uses the CMOS memory to store and retrieve these settings, allowing users to customize various aspects of the computer's operation.  

Which BIOS Upstate should I Choose?

To minimize the risk of issues and ensure compatibility, it is important to consider certain factors when selecting a BIOS update. Below are some guidelines to assist you in choosing the appropriate one. Identify your motherboard model: Determine the specific model of your motherboard. This information is usually printed on the motherboard itself or can be found in the computer's documentation or BIOS settings. Knowing your motherboard model is essential because BIOS updates are specific to each motherboard model. Visit the manufacturer's website: Once you have identified your motherboard model, visit the manufacturer's website. Most motherboard manufacturers, such as ASUS, Gigabyte, MSI, and ASRock, provide support pages with BIOS updates for their products. Check the BIOS update section: Look for the section on the manufacturer's website that provides BIOS updates for your motherboard model. Often, this section is labeled as "Support," "Downloads," or "Drivers." Enter your motherboard model or select it from a list to access the appropriate BIOS updates. Read the release notes: Before downloading and installing a BIOS update, carefully read the release notes or documentation provided by the manufacturer. The release notes typically outline the changes, bug fixes, and improvements included in the BIOS update. Pay attention to any specific instructions or prerequisites mentioned. Consider the need for the update: Evaluate whether you truly need to update your BIOS. BIOS updates are usually released to address specific issues, improve system stability, add compatibility with new hardware, or provide additional features. If you are not experiencing any problems or don't require the new features or compatibility, it may be unnecessary to update your BIOS. Follow the installation instructions: Once you have chosen the appropriate BIOS update, carefully follow the installation instructions provided by the manufacturer. These instructions typically involve downloading the update, creating a bootable USB drive, and running the update utility during system startup. It is crucial to follow the instructions precisely to avoid any potential issues. Backup important data: Before proceeding with a BIOS update, it is always a good practice to back up any critical data on your computer. While the risk is low, there is still a small possibility of complications during the update process. Having a backup ensures that you can restore your system in case of any unforeseen issues. Proceed with caution: Updating the BIOS carries some risks, albeit minimal. Any interruption or error during the update process can potentially render your system inoperable. Therefore, it is important to proceed with caution, follow the manufacturer's instructions precisely, and avoid interrupting the update process. If you're not sure about updating your BIOS or if you're not having any problems, it's best to seek advice from a professional or contact the manufacturer's support.  

Conclusion

In conclusion, BIOS (Basic Input/Output System) is a critical component of any computer system. It serves as the intermediary between hardware and software, facilitating the initialization of hardware components and the booting process. BIOS performs essential tasks such as the Power-On Self-Test (POST), device initialization, and loading of the operating system. Knowing BIOS is important for fixing hardware problems, customizing system settings, and improving performance. Updating BIOS regularly can fix bugs, improve compatibility, and add features. Understanding BIOS basics helps you understand your computer system better and manage hardware and software interactions effectively.