What is UEFI

The Unified Extensible Firmware Interface or UEFI for short is a replacement for the BIOS in modern personal computers.

What is the difference between UEFI and BIOS?

A PC's BIOS is limited to a 16-bit processor mode and 1 MB of addressable space whereas the UEFI processor mode can be either 32-bit or 64-bit and allows applications to have access to all of the available memory.

BIOS uses the standard PC disk partition scheme and a master boot record (MBR) whereas UEFI has a new partitioning scheme, the GUID Partition Table (GPT), which does not suffer the same limitations as MBR, supporting larger and more partitions per disk.

What are the advantages of UEFI?

  • Supports 32 and 64-bit processors
  • Able to access more memory
  • Supports more partitions per disk
  • Supports booting from disks larger than 2TB
  • CPU-independent
  • Can support remote diagnostics and repair
  • Can offer legacy boot mode to emulate BIOS

What are the disadvantages of UEFI?

  • A 64-bit UEFI can only boot a 64-bit UEFI operating system
  • Only supports FAT16 and FAT12 for removable media
  • Not all UEFI firmware offers legacy boot mode restricting the PC's use to UEFI-supported operating systems
  • PC's sold with Windows 8 use secure boot restricting the use of alternative operating systems on the same PC

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Article date: 12th May 2014

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