668 Computer Service and Repair
When POST is complete, some adapters such as video cards or hard disk
drives may carry out their own firmware diagnostics routine that is built into the
device. This is independent from BIOS diagnostics.
The Extensible Firmware Interface (EFI) is a new approach to the BIOS
system. The original BIOS program was first developed in the late 1970s. Before
BIOS, each computer manufacturer had to have a matching operating system
designed especially for that computer. After the BIOS was developed, you
could run a variety of operating systems on the same computer. The BIOS was
responsible for linking the communications between the operating system and
the PC hardware. EFI was first introduced by Intel, but now a large group of
computer hardware manufacturers are involved with creating a set of standards
of design for EFI. The group organization is the United EFI (UEFI). EFI can be
installed to work directly with BIOS or as a replacement for BIOS. EFI is required
on computers that wish to use a new file system directory structure referred to as
GUID. In the future, EFI is expected to replace BIOS.
EFI was not supported by the Windows Vista operating
system at the time of Windows Vista’s original release.
However, the Windows Vista service pack 1 does include
support for EFI system. Apple MAC OS X first started
support of EFI in 2006. EFI is also supported by various
Linux systems such as Red Hat and Novell SUSE. The
Intel Itanium processor is designed to support EFI as well.
Microsoft Windows Server 2003 was the first Microsoft
operating system to support EFI. Hewlett Packard (HP)
also supports EFI on their HP-UX servers, which are Unix-
based systems.
Traditional BIOS is limited in size and typically has less than 1 MB of ROM.
It also uses 16-bit drivers. EFI is not limited in size and can load 32-bit and 64-
bit drivers before the operating system is loaded. EFI can also load and run
applications during the POST without the loading of an operating system. For
example, a diagnostic utility or disaster recovery tool, or even a virus check
program, can be run before the operating system is actually loaded. This is an
extreme difference when comparing BIOS- to EFI- based systems.
BIOS is not governed by any collective organization, and
there is no one set of standards controlling the design
of BIOS code. The United EFI (UEFI) organization has
designed the EFI to be totally vender neutral. This means
no one operating system or no one BIOS manufacturer can
control the firmware coding. All source code is open and
shared so that all software and hardware designers have
full access to the EFI coding. Expect the transition from
BIOS to EFI to be gradual, not abrupt. EFI motherboards
also support traditional BIOS.
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