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EFI (Extensible Firmware Interface) is a replacement for BIOS (Basic Input Output System) that was developed mainly because BIOS was limited to only x86 CPUs in an era when Intel was branching off to other platforms such as Itanium. EFI now represents Intel's future firmware platform, and is pushing for computer manufacturers to support it (with limited success).

Of note, Apple has implemented popular Open Firmware commands, such as Target Disk Mode (T key held down during startup) and startup disk selection (option key held down during startup) in EFI on Intel Macs.

OS's that support EFI

  • Mac OS X 10.4.4+
  • 64 bit Windows (including Vista 64-bit)
  • Windows Server 2003
  • Some Linux distributions

OS's that do NOT support EFI

  • Windows Vista (32-bit)
  • 32 bit Windows (Windows XP, 2000, etc...)
  • Some Linux distributions

See Also