Chapter 6: The BIOS and the Boot Process^109
An Introduction to the BIOS
A PC’s BIOS (Basic Input/Output System) includes the programming to perform three
vital and useful functions for the PC: It boots the computer.
It validates the PC’s configuration.
It provides an interface between the hardware of the PC and its software.The BIOS Utilities and Programs
InadditiontostartingupaPC,theBIOSalsocontainsacollectionofprogramsthatareused
by an operating system and application software to interact with the hardware, both inter-
nal and external, connected to the PC. While operating systems are beginning to include
device drivers and utilities of their own to improve performance, most BIOSs contain soft-
ware for accessing, reading, writing, and moving data between virtually every type of
hardware device.BIOS Manufacturers
The most well-known BIOS manufacturers are Award, AMI (American Megatrends,
Inc.), and Phoenix. Like most BIOS manufacturers, these three license their BIOS ROM to
motherboard manufacturers who install them on their motherboards and assume the
support of the BIOS as well. AMI was once the sole BIOS provider to Intel, the leading
motherboard producer. Today, over 80 percent of all motherboards are Intel boards that
include a Phoenix BIOS. In 1998, Phoenix purchased Award and now markets the Award
BIOS brand under the Phoenix name.Booting the Computer
The process used to start up a PC each time it is powered on is called theboot process.
While it sounds like it could refer to kick-starting, this term is actually derived from the
saying, “Pulling one’s self u pby one’s own bootstra ps,” which is a long-winded way of
saying you are a self-starter. PCs are self-starters in the respect that when you flick on the
power switch, the PC verifies its hardware configuration, runs a few function tests, and
then gets its operating system loaded into memory and running on the CPU. It’s almost
like magic...well, not quite.
The boot process is performed under the guidance of the BIOS. The BIOS contains the in-
structions needed to verify, test, and start the PC—in other words, boot the computer. When the
computer boots up, the BIOS is behind the scenes causing and managing the actions that are
taking place. The PC’s hardware cannot perform independent actions. It must have instructions
to do anything at all. These instructions are in the form of the PC’s software, which are blocks of
instructions that guide the hardware to perform specific activities.