Chapter 2 Operating Systems 65
(MBR), which is typically located on the first
section of the hard drive; loads into memory some
basic files; and then turns the boot operation over
to the operating system. The word bootstrap comes
from the expression ”to pull oneself up by one’s
bootstraps.”
UEFI
The boot sequence is slightly different for a
computer equipped with UEFI, or EFI. The Unified
Extensible Firmware Interface (UEFI) is a modern
approach to the BIOS system and an enhancement
to the boot process. When a device equipped with
UEFI completes POST, control is turned over to
a built-in boot manager program rather than the
MBR, which contains the bootstrap program.
The UEFI firmware uses an improved hard drive
technology known as GUID partition table. There
will be more about UEFI and GUID later in this
textbook when you have a better understanding of
data storage and system files.
Some computers have an UEFI boot manager
and an MBR to ensure backward compatibility. UEFI
is backward compatible with devices and software
that require BIOS firmware. The UEFI firmware
directly supports BIOS features using a compatibility
support module (CSM), which is programmed into
the UEFI. The CSM emulates the BIOS features.
For example, when a computer system that has
BIOS firmware is upgraded to a new operating
system that uses UEFI firmware and supports the
GUID partition table, the UEFI technology will use
CSM to support a BIOS MBR partition. This way,
backward compatibility is maintained.
Windows operating systems began support for
EFI and UEFI with the release of Windows Vista.
Windows operating systems must be 64-bit versions
to use UEFI.
Windows 8 was designed with a secure boot-
sequence to prevent malware and unauthorized
changes to the operating system. By default,
Windows 8 installs the boot-sequence for the
use of UEFI firmware. Windows 8 does have the
ability to run on computers designed with BIOS,
but some of the security features will not be
installed because BIOS cannot implement these
features. UEFI firmware protects the computer
before the start of the Windows 8 operating
system. The UEFI system allows the anti-malware
program to begin before the operating system
starts. The early start of anti-malware software
helps to prevent attacks on the computer before
operating system is loaded. Also, Windows 8 only
allows the installation of Microsoft preapproved
software applications. The purpose of this is to
prevent malware applications from altering or
damaging the system configuration. There will
be much more about UEFI protection later in
Chapter 14—Physical and Digital Security.
Because the term BIOS
is so ingrained in com-
puter technician jargon, it
will still be used for many years to represent the
correct term firmware and UEFI. Although not
technically correct, this is the way technical
language commonly evolves. You will often
encounter terms that are not always correct when
reading resource materials and talking to other
technicians.
Windows NT-Based Boot Sequence
Windows NT was the first Microsoft
operating system to be fully developed so that
it is independent of the restrictions of DOS. It is
a completely redesigned operating system with
a new kernel. Windows 2000 and Windows XP
are typically identified as Windows NT-based
operating systems because they are built on the
Windows NT kernel.
The Windows NT boot sequence is described
as a series of phases rather than a series of files
executed one after another. These phases are listed
in the first column of the table in Figure 2-31.
Some files are loaded into memory during the
boot process and are used to provide information
to the file that is presently in control of the boot
operation. You might say that the boot operation
is no longer a series of files taking over one by
one, but rather several files working together
to complete the boot operation. Figure 2-32
provides a description of the Windows NT-based
boot process files. The following details the
Windows NT boot sequence.
1. BIOS performs the POST.
2. BIOS locates the MBR and loads it into
memory.
Tech Tip