don’t ever think about controller chips on their systems. In fact, most users probably don’t
even know they exist. How data gets to and from the keyboard is not of concern, only that
it does.
On a PC, a controller is typically a single chip that either mounts directly on the moth-
erboard or on a card that is inserted in an expansion slot on the motherboard. Because
they control the flow of data to and from peripheral devices, controllers must be matched
to the bus architecture of the PC.Bus Architectures
The bus architecture of the PC is made u pof the wires, connectors, and devices that move
data and instructions around the PC (see Chapter 11 for more information on expansion
bus architectures). The bus structure, which got its name from the fact that it resembles
thelinesonacitybusmap,connectsthecontrollersonthemotherboard,theCPU,memory,
I/O ports, and expansion slots.
The PC’s bus architecture becomes very important when you add additional device
controller cards to the motherboard’s expansion slots. Most of the latest motherboard de-
signsincludeexpansionslotsformultiplebusstructures,includingPCI(PeripheralCom-Chapter 5: Chipsets and Controllers^89
Figure 5-3. Controller chips control individual I/O or devices. Photo courtesy of Ines, Inc.