Hardware Reference
In-Depth Information
or IOH (I/O Hub) and South Bridge or ICH (I/O Controller Hub). Many newer processors
integrate the functions of the first chip into the processor and call the remaining chip a
PCH (Platform Controller Hub). The chips in the chipset replace the 150 or more distinct
components that were used in the original IBM AT systems and enable a motherboard de-
signertoeasilycreateafunctionalsystemfromjustafewparts.Thechipsetcontainsmost
of the motherboard circuitry except the processor and memory in most systems.
Becausethechipsetreally
is
themotherboard,thechipsetusedinagivenmotherboardhas
a profound effect on the performance of the board. It dictates all the performance para-
meters and limitations of the board, such as memory size and speed, processor types and
speeds, supported buses and their speeds, and more.
Because chipsets are constantly being introduced and improved over time, I can't list all
of them and their functions here; however, you will find a detailed description of many of
Clearly, you must base the selection of a chipset largely on the processor you choose and
the additional components you intend to install in the computer.
The chipset dictates what types of bus slots can be included on the motherboard. Most re-
cent chipsets include Peripheral Component Interconnect (PCI) and PCIe (PCI Express)
slots only; if you have Industry Standard Architecture (ISA) or Accelerated Graphics Port
(AGP) cards, they won't be usable in any new system you build or buy.
If you really want in-depth technical information about the chipset in a given mother-
board, I recommend downloading its documentation (often called the
databook
). This
documentation should also help describe the Advanced Chipset Setup functions in your
system'sSetupprogram.Withthisinformation,youmightbeabletofine-tunethemother-
board configuration by altering the chipset features and settings.
BIOS / UEFI
Another important feature on the motherboard is the basic input/output system (BIOS).
This is also called the
ROM BIOS
because the code is stored in a read-only memory
(ROM) chip. There are several things to look for here. Most BIOSs are supplied by one
of the major BIOS manufacturers, such as AMI (American Megatrends International),
Phoenix,orAward(ownedbyPhoenix).TheBIOSisnormallycontainedinaspecialtype
of reprogrammable chip called a
Flash ROM
or
EEPROM
(electrically erasable program-
mable read-only memory). This enables you to download BIOS updates from the manu-
