

System Board Components
Chipsets
Expansion slots
Memory slots and external cache
CPU and processor slots or sockets
Power connectors
Onboard disk drive connectors
Keyboard connectors
Peripheral port and connectors
BIOS chip
CMOS battery
Jumpers and DIP switches
Firmware
Chipsets
A chipset is a collection of chips or circuits that perform interface and peripheral functions for the
processor. This collection of chips is usually the circuitry that provides interfaces for memory,
expansion cards, and onboard peripherals and generally dictates how a motherboard will talk to
the installed peripherals.
Chipsets are usually given a name and model number by the original manufacturer. For
example, if you see that motherboard has a VIA KT7 chipset, you would know that the circuitry
for controlling peripherals was designed by VIA and was given the designation KT7.
Typically, that would also mean that you would know that a particular chipset has a certain
set of features (for example, onboard video of a certain type/brand, onboard audio of a particular
type, and so on).
Chipsets can be made up of one or several integrated circuit chips. Intel-based motherboards
typically use two chips, whereas the SiS chipsets typically use one. To know for sure,
you must check the manufacturer’s documentation.
The functions of chipsets can be divided into two major functional groups, called Northbridge
and Southbridge. Let’s take a brief look at these groups and the functions they perform.
Expansion Slots
The most visible parts of any motherboard are the expansion slots. These look like small plastic
slots, usually from 3 to 11 inches long and approximately 1.2 inch wide. As their name suggests,
these slots are used to install various devices in the computer to expand its capabilities. Some
expansion devices that might be installed in these slots include video, network, sound, and disk
interface cards.
If you look at the motherboard in your computer, you will more than likely see one of the
main types of expansion slots used in computers today:
_ ISA
_ PCI
_ AGP
_ PCIe
_ AMR
_ CNR
Each type differs in appearance and function. In this section, we will cover how to visually
identify the different expansion slots on the motherboard.
ISA Expansion Slots
If you have a computer made before 1997, chances are the motherboard has a few Industry
Standard Architecture (ISA) expansion slots. They’re easily recognizable because they are
usually black and have two parts: one shorter and one longer. Computers made after 1997
generally include a few ISA slots for backward compatibility with old expansion cards
(although most computers are phasing them out in favor of PCI). Figure 1.4 shows an example
of ISA expansion slots.
PCI Expansion Slots
Most computers made today contain primarily Peripheral Component Interconnect (PCI)
slots. They are easily recognizable because they are short (around 3 inches long) and usually
white. PCI slots can usually be found in any computer that has a Pentium-class processor or
higher. Figure 1.5 shows an example of several PCI expansion slots.
AGP Expansion Slots
Accelerated Graphics Port (AGP) slots are very popular for video card use. In the past, if
you wanted to use a high-speed, accelerated 3D graphics video card, you had to install the
card into an existing PCI or ISA slot. AGP slots were designed to be a direct connection
between the video circuitry and the PC’s memory. They are also easily recognizable because
they are usually brown, are located right next to the PCI slots on the motherboard, and are
shorter than the PCI slots. Figure 1.6 shows an example of an AGP slot, along with a PCI
slot for comparison. Notice the difference in length between the two.
PCIe Expansion Slots
The newest expansion slot architecture that is being used by motherboards is PCI Express
(PCIe). It was designed to be a replacement for AGP and PCI. It has the capability of being
faster than AGP while maintaining the flexibility of PCI. And motherboards with PCIe will
have regular PCI slots for backward compatibility with PCI.
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