Chapter 1 Introduction to a Typical PC 21
Expansion Cards
Expansion cards are sometimes called interface
cards or host adapters. An expansion card is a
board that can be easily installed in a computer to
enhance or expand its capabilities. An expansion
card allows the computer to be custom-designed
to meet the needs of different consumers,
Figure 1-31. A certain computer may have video
circuitry integrated into the motherboard or a
separate video card that only allows for minimal
video performance. The performance of this
video system would be adequate for accounting
or word-processing functions. However, it would
be substandard for computer-aided drafting or
game applications. To remedy this, a new video
card, or video expansion card, can be added to the
computer system.
Expansion cards are used for such devices
as TV tuners, video cards, sound cards, and
telephone modems. They can also provide
additional USB ports for connecting external
devices such as hard drives. Many devices that
were designed as expansion cards for internal
installation have been redesigned as exterior
devices that connect to the computer, typically
through a USB port.
Expansion Card Slots
An expansion card fits snugly into an
expansion card slot, Figure 1-32. The expansion
card slot, also called an expansion slot, allows
the expansion card to connect directly to the
electronic circuitry in the motherboard and to
communicate directly or indirectly with other
components on the motherboard or with the
CPU. There are several types of expansion slots.
The most common expansion slots are PCI and
PCIe. Expansion cards are discussed in detail in
Chapter 3—Motherboards.
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Figure 1-30. Batteries allow information such as the date
and time to be saved while a PC is powered down.
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Figure 1-31. Expansion cards allow computers to do many
different things. This is a PCIe video card.
PCI Express (PCIe)
slots
PCI slots
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Figure 1-32. A variety of expansion card slots are built into
most motherboards. This motherboard has PCI and PCI
Express (PCIe) expansion slots.