UEFI BIOS explained

Since UEFI is a software environment, its high-level functions aren’t tied to any particular platform: UEFI works on ARM devices as well as regular PC hardware, and there’s no reason it can’t be compiled for any other architecture that may come along.

Who created UEFI?

UEFI has been under development for a lot longer than you may realise. Chip giant Intel first started work on a replacement for the classic PC BIOS back in 1998, to partner its nascent Itanium platform. In 2002, its fruits were formalised as the Extensible Firmware Interface (EFI).

Intel hasn’t kept the standard to itself. Since 2005, the system has been managed and developed by a cross-industry working group, including not only Intel but also AMD, Apple, Dell, Lenovo and Microsoft. The organisation is called the Unified EFI Forum – hence the addition of the “U” to UEFI.

You might wonder why UEFI didn’t catch on sooner. In fact, the system in its various versions has been quietly gaining momentum for a long time. In 2006, Apple switched all new Macintosh hardware from PowerPC processors over to the Intel platform, and chose the original EFI for its pre-boot firmware, a system it uses to this day. Some Windows laptops have also started using UEFI in the past few years, in order to provide friendlier and more flexible pre-boot environments. This hasn’t attracted much attention, for the simple reason that it makes no visible difference to most end users. And in the cut-throat desktop market, PC motherboards have tended to stick with traditional BIOS rather than invest in the more sophisticated UEFI. Until now, that is.

UEFI and Windows 8

Historically, Windows hasn’t got along well with UEFI hardware. In fact, back in 2006, when enthusiasts tried installing Windows XP on the first Intel-based iMacs, they were stymied precisely because Windows XP – the current version at that time – has no ability to boot on an EFI system. The situation was resolved only when Apple issued a firmware update allowing Mac hardware to emulate a traditional BIOS (along with a driver pack enabling Apple’s hardware to work in Windows). This shows the power of UEFI’s open-ended design.

Windows Vista and 7 didn’t fully support UEFI either, but there were good reasons for this. A 32-bit operating system can boot only from 32-bit UEFI firmware, while a 64-bit OS requires 64-bit firmware. When Microsoft introduced Windows Vista in both 32- and 64-bit flavours, nobody wanted to tell users they’d have to reprogram their motherboards to match their Windows edition – and motherboard manufacturers didn’t want to support two parallel versions of their UEFI firmware anyway. So Microsoft settled on a compromise: UEFI was supported natively by 64-bit editions of Vista, and latterly Windows 7, while 32-bit editions continued to require a BIOS, either real or emulated.

In Windows 8, the situation has changed, and Microsoft has wholeheartedly embraced UEFI. Its certification standards require that all new desktops, laptops and tablets sold with Windows 8, and bearing the Windows 8 sticker, must use a UEFI BIOS. You can still upgrade an older non-UEFI system to Windows 8, however – you’ll simply miss out on a handful of useful features, as we’ll describe below.