The Differences Between UEFI And BIOS

BIOS and UEFI both are the firmware interfaces that act as an interpreter between the system’s firmware and operating system. A firmware interface initializes the hardware components while the startup of a computer system.

Here we will cover BIOS, UEFI, and their limitations or features so that anyone who reads this has a basic understanding of the given topics and is able to differentiate between these two.

Basic Input Output System (BIOS)

When a computer starts up, BIOS loads and initializes the different hardware components of a system. The BIOS comes preinstalled on a computer’s system board and it is the first software that runs when the system power on.

BIOS reads the first sector of the hard disk and establishes a few services in 16-bit real mode. It also selects the devices to be initialized for starting the operating system. Since BIOS is used from the very beginning it has some limitations.

Limitations of BIOS

  • BIOS can support and boot from a drive that is less than 2 TB. Nowadays hard drives of size more than 2TB are used at various places.
  • It runs in 16-bit processor mode and has one MB of space to execute code.
  • BIOS can’t initialize multiple hardware at once which leads to slow booting speed.

Unified Extensible Firmware Interface (UEFI)

UEFI is the firmware interface that is intended to replaces the legacy BIOS. Most of the UEFI implementation provides support for the legacy BIOS system. It can support remote diagnostics and repair even when there is no operating system on a computer.

It works a little bit differently it stores all the information such as initialization and startup of a system in .efi file which resides into a separate partition called EFI system partition(ESP). This partition also contains the bootloader program required for booting an operating system.

Features and advantages of UEFI

  • UEFI is able to use large disk partition (over 2 TB)
  • It is backward and forward compatible
  • UEFI can support remote diagnostics and repair
  • Provide a flexible pre OS environment and network capability
  • It also provides the feature of secure boot that prevents from rootkits
  • UEFI can run in both 32 and 64-bit modes, it provides better UI configuration that supports mouse and cursor


UEFI brings new features and enhancement that can not be implemented through BIOS. Some newer pc allows you to run UEFI in legacy BIOS mode.

This article intends to provide you a basic understanding of UEFI and BIOS and the differences between them. So after reading this if you have any queries on this then you can write to us in the comments below.

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