What is the difference between BIOS and UEFI?

They both control the boot process of a computer but work in different ways and provide different options.

BIOS (Basic Input/Output System) is firmware used during the boot process on a PC.  BIOS is responsible for the communication between the operating system and the I/O (input/output) devices, such as the keyboard and the monitor.  When the computer is powered on, the BIOS performs a Power On Self Test (POST) which checks different hardware to make sure they are working properly.   Finally, it looks on the first sector of the hard drive for instructions on how to boot the operating system (OS) and then the OS takes over from there.  BIOS will only support MBR partitions with storage restrictions of 2TB.

UEFI (Unified Extensible Firmware Interface) is also firmware used during the boot process but can be used for Mac or PC.  UEFI does the same thing as BIOS with a more user-friendly interface, making it easier for the end-user to make changes to the system.  UEFI also allows the use of GPT partitions which are able to handle storage capacities up to 8 Zettabytes (ZB) which is equal to 8 billion Terabytes (TB).  It also has the ability to boot off of a hard drive that is larger than 2 TB, as long as the motherboard supports it.  UEFI stores the startup information in a .efi file instead of on the firmware and stores it in an EFI system partition (ESP) on the hard drive.  The .efi file contains the boot loader for the installed operating systems, device drivers that are necessary for the boot process, any system utilities that run before the OS is booted and data/log files.  Different than BIOS, UEFI controls the boot process rather than handing it over to the OS.

If you have any questions, feel free to contact us or come into our store to speak to a technician.