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What Is BIOS (Basic Input/Output System)?

The process of starting a computer involves an essential system known as Basic Input/Output System, or BIOS. This system plays a vital role in ensuring that all the necessary hardware components are operational and ready for the initiation of the software. The importance of BIOS lies not only in its role in booting up a computer but also in its function as a communication link between the operating system and hardware.

What is BIOS?

BIOS is essentially the program a personal computer’s microprocessor uses to get the computer system started after you turn it on. It also manages data flow between your computer’s operating system and attached devices such as the hard disk, video adapter, keyboard, mouse, and printer.

How does BIOS work?

Upon powering up your computer, BIOS first performs a series of checks known as the Power-On Self Test (POST) to ensure the components of the system are working correctly. Once the POST is complete, BIOS activates other software programs that can take over from there.

Purpose of BIOS

The main purpose of BIOS is to initialize and test the system hardware components, and to load a bootloader or an operating system from a mass memory device. It provides an abstraction layer for the hardware, i.e., it acts as an intermediary between the computer’s hardware and its operating system.

Is BIOS secure?

While BIOS is an integral part of a computer’s functioning, it is not immune to threats. Hackers can target BIOS to introduce malicious code into a computer system. However, most modern computers come equipped with features that protect BIOS from such unauthorized access.

Four main types of BIOS

1) 1st generation BIOS

The first generation BIOS was the original version, used in the early days of computers. It was stored on a ROM chip on the motherboard.

2) EFI (Extensible Firmware Interface)

EFI was designed to overcome some limitations of the traditional BIOS, offering improved benefits such as better scalability and extensibility, and more flexible pre-OS environments.

3) UEFI (Unified Extensible Firmware Interface)

UEFI is a modern version of BIOS that addresses its technical restrictions. It provides faster boot times, improved security measures, and support for drives larger than 2.2 terabytes.

4) Mac equivalent: Open Firmware

For Mac systems, the equivalent of BIOS is known as Open Firmware. This system is based on the Open Firmware standard, which is similar to EFI.

BIOS manufacturers

  • American Megatrends Inc. (AMI)
  • Phoenix Technologies
  • Award Software
  • Dell
  • HP
  • Lenovo

How to access BIOS in 5 steps

  1. Start your computer: Begin by starting or restarting your computer.
  2. Access the boot screen: As soon as the computer starts, press the appropriate key to enter the boot screen. This key varies depending on the computer’s manufacturer.
  3. Enter BIOS: From the boot screen, select the option to enter BIOS setup.
  4. Navigate the BIOS menu: Use the navigation instructions given on the BIOS screen to change settings or boot order.
  5. Save and exit: After making the necessary changes, save the changes and exit BIOS.


While it may seem complex initially, with patience and perseverance, one can easily understand and even troubleshoot issues related to BIOS. Remember, every component in the world of IT has its unique importance and purpose, and BIOS is no exception.

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