Hardware Reference
In-Depth Information
supporting the latest UEFI specifications, which most motherboard manufacturers have incorporated
in the motherboards they make.
BIOS Hardware/Software
Some important drivers must be active during boot time. For example, how can you boot from a hard
disk if the drivers necessary to make the disk interface work must be loaded from that disk?
Obviously, at least a minimum level of hard disk drivers must be preloaded into ROM either on the
motherboard or on an adapter card for the system to be able to boot.
As another example, how can you see anything onscreen prior to booting if your video card or GPU
(graphics processing unit) doesn't have a set of drivers in a ROM? The solution to this could be to
provide a motherboard ROM with the appropriate video drivers built in; however, this is impractical
because of the variety of video cards/GPUs, each needing its own unique drivers. Instead, when IBM
designed the original PC, it designed the PC's motherboard ROM to scan the slots, looking for
adapter cards with ROMs on them. If a card was found with a ROM on it, the ROM was executed
during the initial system startup phase, before the system began loading the OS from the hard disk.
A few cards (adapter boards) almost always have a ROM onboard, including the following:
•
Video cards/GPUs
—All have an onboard BIOS.
•
RAID (Redundant Array of Independent Disks)
cards enable you to attach multiple drives
and array them in different ways to improve reliability, redundancy, and performance. These
cards require an onboard BIOS to enable the array to be bootable.
•
Network cards
that support booting directly from a file server have what is usually called a
boot ROM or IPL (initial program load) ROM onboard. This enables PCs to be configured on a
local area network (LAN) as diskless workstations—also called Net PCs, NCs (network
computers), thin clients, or even smart terminals. Intel developed a standard for network
booting that it calls the PXE (Preboot eXecution Environment).
•
ATA/Serial ATA (SATA) upgrade boards
—Boards that enable you to attach more or
different types of drives than what is typically supported by the motherboard alone. In some
cases these cards require an onboard BIOS to enable these drives to be bootable.
Upgrading the BIOS
Motherboard manufacturers tailor the BIOS code to the specific hardware on each board. This is
what makes upgrading a BIOS somewhat problematic; the BIOS usually resides in one or more ROM
chips on the motherboard and contains code specific to that motherboard model or revision. In other
words, you must get your BIOS upgrades from your motherboard manufacturer or from a BIOS
upgrade company that supports the motherboard you have, rather than directly from the original core
BIOS developer.
Although most BIOS upgrades are done to fix bugs or problems, you must often upgrade the BIOS to
take advantage of some other upgrade. For example, a BIOS upgrade often adds support for newer
processors, and may add other features like UEFI (Unified Extensible Firmware Interface), larger
internal hard drives, bootable optical and USB drives, faster booting, and more.
If you install newer hardware or software and follow all the instructions properly but you can't get it
to work, specific problems might exist with the BIOS that an upgrade can fix. This is especially true
for newer OSs. Many older systems need to have a BIOS update to properly work with newer
