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What is BIOS?

What is BIOS

BIOS is a program, stands for basic input/output system, which is stored in nonvolatile memory like ROM (Read Only Memory) or flash memory that allows you to set up and access your computer system at the greatest basic level. Although there is no need for most people to mess with the BIOS on a computer, it can be better to know about BIOS. It is found on motherboards that are a pre-installed program on Windows-based computers that executes when a computer is powered up. Before an OS is loaded, the CPU accesses the basic input/output system (BIOS). Then, the next function of BIOS is to examine all the hardware connections and detects all your devices.

The main function of BIOS is to set up hardware and start an OS, and it contains generic code that is needed to control display screens, the keyboard, and other functions. The BIOS is built-in software that manages the hard drives and cannot live on one. It cannot reside in the RAM (Random Access Memory) as it is accessible before the computer system boots up. Actually, it lives on the ROM of the computer system, and mainly it is located on EPROM (erasable programmable read-only memory) chip. Therefore, the CPU accesses the EPROM when you turn on the computer and provides control to the BIOS.

The primary intention of designing the BIOS system is to function with numerous devices that led to making a complimentary system chipset. There are some functions contained by the BIOS library that operates and controls system peripherals, and they can be initiated through external software.

Users can perform different functions by using the BIOS user interface, which is discussed below:

  • Users can perform hardware configuration
  • They can select boot drives
  • They can set the system clock
  • The BIOS allows users to enable and disable certain system components
  • To BIOS user interface function, it provides set password prompts for secured access

The BIOS works as an intermediary between the I/O devices and the CPU and is used after the computer has booted up. The BIOS works as an intermediary between the I/O devices and the CPU and is used after the computer has booted up. Your operating system and programs do not need to know the details about the I/O devices connected to your system because of the BIOS. You can change these settings accordingly with the help of entering the BIOS setup at the time of your system starts up. Furthermore, if you want to access the BIOS setup, you can hold down the DELETE or F2 key when your computer starts up.

BIOS is stored in rewritable memory in some modern PCs, which allow information to be replaced or rewritten. Such content rewriting is executed with the help of a special program offered by system manufacturers.

BIOS Availability

The BIOS software is available in all modern computer motherboards. As the BIOS is a part of the motherboard; therefore, the BIOS's access and configuration on PCs are independent of any type of operating system. The BIOS is not dependent on anyone that means it does not matter which types of an operating system is running on the computer like Windows 7, Windows 8, Windows 10, Windows XP, Linux, Windows Vista, Unix, or no operating system at all, BIOS functions outside of the operating system environment.

What is included in a BIOS?

The directions to load basic computer hardware are included in BIOS software. A test is also included within it that is referred to as a POST (Power-On Self-Test). The POST helps the computer to boot up properly with verifying the computer meets requirements. Your computer produces various forms of beeps if the POST test fails at the time of test.

Functions of BIOS

The BIOS has different instructions that are required to load the hardware, and it is responsible for loading the operating system. The major functions of a Basic input/output system (BIOS) are discussed below:

  • BIOS Power on Self-Test (POST): It ensures the proper functioning of the computer hardware as it is a built-in diagnostic program that. In the system, it verifies the computer meets the necessary parts and functionality. POST does this function efficiently. It ensures that the computer is loading tasks successfully, such as the use of memory, a keyboard, and other parts when it starts up. If the POST test fails at the time of test, the computer provides a combination of beeps to display the error type, and the system continues to boot when the POST test is passed completely.
    Once the self-test has been passed, and the basic instructions have been loaded, the computer starts to load the OS from one of the connected drives to the system. The BIOS settings can also be changed by the computer users with the help of a configuration screen on the computer. The BIOS information can also be stored on the flash memory, which can be updated by computer users after releasing an update by vendors. BIOS actually can be located in between the external devices and the computer because its name describes that it is used for reading and writing to and hard disk and floppy disc, displaying values on the screen, reading the keystroke, etc.
  • Bootstrap Loader: The BIOS recognizes and locates the operating system when the POST running successfully. The program bootstrap loader is contained by BIOS, which searches and starts the OS boot program. When BIOS detects one, it transfers access to Operating System that is known as booting.
  • BIOS drivers: BIOS drivers are stored in the non-volatile memory, whose primary function is to supply basic computer hardware information.
  • BIOS Setup Utility Program: It is a configuration software, also known as CMOS setup, that allows users to configure hardware settings as well as device settings, time and date, computer password. The NVRAM, non-volatile memory, is used to store settings of memory, disk types, and information about the computer system; this information is not stored in the BIOS chip

The users run the BIOS setup program during the installation of a system and input the correct parameters. The CMOS (Complementary metal-oxide-semiconductor) is a required material to construct NVRAM. These CMOS chips store and maintain data on very low values of current. Therefore, the system's configurations are also called CMOS settings. With the help of using a capacitor, maintaining the battery backup, or by a battery built into the NVRAM chip, CMOS settings can be maintained. Additionally, a system clock is also included in this chip. The setting remains for a short period of time if there is no battery. And there is a need to reset the system. Through its BIOS set up program is protected as there is loss of BIOS password.

With computers, BIOS come in-built as firmware on a chip on the motherboard. In contrast, an operating system such as iOS or Windows can be installed by the user or pre-installed by the vendor or manufacturer.

When BIOS boots up a computer, it verifies the computer meets the necessary attachments to boot up. The files are contained by any piece of hardware that needs for a computer to start up, this piece of hardware is known as a boot device.

Different types of BIOS

The BIOS screen is seen by every PC user, it does not matter he knows it or not each time he turns on his computer system. The computer's manufacturer displays the screen is called the Basic Input/Output System (BIOS). The BIOS has mainly two types, which are as follows:

  1. UEFI: The UEFI can accommodate 2.2 TB or larger drives, which stands for Unified Extensible Firmware Interface. It handles drives with the help of using the Master Boot Record instead of GPT technology, the more modern GUID Partition Table. Furthermore, Apple's Mac PCs have never used the BIOS.
  2. Legacy BIOS: The Legacy BIOS was used in older motherboards to turn the PC on. Legacy BIOSes have limitations as they have no ability to handle or recognize drives bigger than 2.1 TB. However, it controls how the CPU and the components communicate with each other.


Most probably, you will see UEFI rather than the BIOS in most modern computers. But what are the differences between both UEFI and BIOS? It can be difficult to differentiate both because they almost perform the same function. UEFI is the same as BIOS, stands for Unified Extensible Firmware Interface, and acts as an intermediate program between the hardware and the OS.

As compared to BIOS, UEFI offers more features and can be extensively customized. In order to load the operating system, it does not need a separate program of a bootloader. It has the ability to manage hard drives that can be exceeded two Terabytes as it offers native support GPT, and BIOS is unable to provide this.

Upgrading a BIOS

Often, it is discovered that when the computer needs to be upgraded with latest hardware, it does not support all the features of the latest hardware. It needs to be upgraded hardware like more memory, a larger hard drive, or a new video card. Upgrading the BIOS chip is an easier solution to this problem. Generally, to upgrade BIOS on the system, the files and information are available on the computer's or motherboard maker's Web site.

Unluckily, it is most important to know that upgrading the BIOS can be a drastic step. If you are going to upgrade the BIOS, you will be better to back up all of your data from the hard drive. Also, make sure there is a recovery jumper that makes you capable of recovering the original BIOS. Although upgrading the BIOS is trouble-free, it is possible for the by upgrading BIOS the system can be computer unusable, damage or destroy the BIOS chip.

A brief history of BIOS

The term BIOS (Basic Input/Output System) first appeared in the CP/M operating system in 1975 and was created by Gary Kildall. It was used to describe the machine-specific part of CP/M loaded during the boot time. These ideas were adopted by Microsoft DOS in the first versions of DOS, which included similar. The files used in CP/M were very close to COM and.SYS files.

The PC's BIOS was held on PROM or ROM chips that were placed on the computer's motherboard through the early 1990s. Some companies, such as Phoenix Technologies, reversed the BIOS originally proprietary to the IBM PC, creating compatible systems. Also, in the mid-1990s, the BIOS was shifted to being stored on EEPROM chips or flash drives on the computer, as to update the BIOS, and demand for complexity increased. In modern times, some computers can have the BIOS, which size can be more than 16 megabytes.

The System BIOS was divided by IBM into real- and protected-mode portions when the PS/2 machines were introduced. The real-mode portion was mainly responsible for offering compatibility with existing OS like DOS, that's why it's named was CBIOS, while new interfaces were provided by ABIOS that was especially ideal for multitasking operating systems such as OS/2.

How to check the version of BIOS?

You are required to access the BIOS setup if you want to check the type or version of BIOS on your computer system. You will see the BIOS version or type on the main BIOS display such as Phoenix, Award, AMI, and more other kinds of the BIOS.

BIOS security

BIOS security somewhere is a unique component of cybersecurity. However, there is still a need to manage it because there are various hackers who can run malicious code on the OS, which can be more harmful. In 2017, inside a motherboard's UEFI, how modern BIOS security flaws could enable ransomware programs it showed by security group Cylance. And other PCs get the benefit of BIOS vulnerabilities.

BIOS manufacturers

In the beginning, BIOS was fundamentally owned by IBM. However, IBM's original version was reverse-engineered by some other companies like Phoenix Technologies to create their own. For doing that, other companies have permission to create clones of the IBM PC by Phoenix. Also, an important thing that they can create non-IBM computers that work with BIOS. Compaq was one company that did this. In modern times, there are various manufacturers of the motherboard with BIOS chips; some are as follows:

  • Foxconn
  • AMI
  • Hewlett Packard (HP)
  • Ricoh
  • Asus

It may be very important to know about the motherboard manufacturer as users sometimes need to update their BIOS and chipset drivers. The operating system functions with other devices in the computer through the drivers. For example, a video card to the most recent versions. When you update drivers, the patch can cause recent BIOS-level security vulnerabilities, or computer performance can be improved.

Does Macs have BIOS?

The operating system (OS) has a BIOS; it is a misperception by Mac users as Macs do not use EFI. Traditionally, they have used G4 Mac Minis, eMacs, iBooks, iBooks, Dual G5s, and OpenFirmware for PowerBooks, etc. There will be an audible chime if the sound is turned on.

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