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Computer Basics
Inside a Desktop Computer
Inside a desktop computer
Have you ever looked inside a computer case before, or seen pictures of
the inside of one? The small parts may look complicated, but the inside of
a computer case really isn't all that mysterious. This lesson will help you
master some of the basic terminology and understand a bit more about
what goes on inside a computer casing.
A look inside a desktop computer
Let's explore the inside of a computer tower.
The central processing unit (CPU),
also called a processor, is located
inside the computer case on the
motherboard. It is sometimes called the
brain of the computer, and its job is to
carry out commands. Whenever you
press a key, click the mouse, or start an
application, you're sending instructions to the CPU.
The CPU is generally a two-inch ceramic square with a silicon chip
located inside. The chip is usually about the size of a thumbnail. The CPU
fits into the motherboard's CPU socket, which is covered by the heat sink,
an object that absorbs heat from the CPU.
A processor's speed is measured in megahertz (MHz), or millions of
instructions per second, and gigahertz (GHz), or billions of instructions
per second. A faster processor can execute instructions more quickly.
However, the actual speed of the computer depends on the speed of many
different components—not just the processor.
There are many processor manufacturers for personal computers, but
the most well-known ones are Intel and AMD.
Inside a Desktop computer
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A motherboard
The motherboard is the
computer's main circuit
board. It's a thin plate that
holds the CPU, memory,
connectors for the hard
drive and optical drives,
expansion cards to control
the video and audio, and connections to your computer's ports (such as
USB ports). The motherboard connects directly or indirectly to every part
of the computer.
Power supply unit
A power supply unit
The power supply unit in a
computer converts the power
from the wall outlet to the type
of power needed by the
computer. It sends power
through the cables to the
motherboard and other
If you decide to open the computer case and take a look, make sure to
unplug the computer first. Before touching the inside of the computer,
you should touch a grounded metal object (or a metal part of the
computer casing) to discharge any static buildup. Static electricity can
be transmitted through the computer circuits and ruin them.
RAM (random access memory)
RAM is your system's short-term
memory. Whenever your computer
performs calculations, it
temporarily stores the data in the
RAM until it is needed.
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This short-term memory disappears when the computer is turned off. If
you're working on a document, spreadsheet, or other type of file, you'll
need to save it to avoid losing it. When you save a file, the data is written
to the hard drive, which acts as long-term storage.
RAM is measured in megabytes (MB) or gigabytes (GB). The more
RAM you have, the more things your computer can do at the same time. If
you don't have enough RAM, you may notice that your computer is
sluggish when you have several programs open. Because of this, many
people add extra RAM to their computers to improve performance.
A bit is the smallest unit of data in computer processing. A byte is a
group of eight bits. A megabyte contains about one million bytes, and
a gigabyte is about one billion bytes.
Hard drive
A hard drive
The hard drive is the data center
of the computer. This is where the
software is installed, and it's also
where your documents and other
files are stored. The hard drive is
long-term storage, which means the
data is still saved even if you turn
the computer off or unplug it.
When you run a program or open a file, the computer copies some of the
data from the hard drive onto the RAM so it can access the data more
easily. When you save a file, the data is copied back to the hard drive.
The faster the hard drive is, the faster your computer can start up and load
Most hard drives are hard disk drives, which store data on a magnetic
platter. Some computers now use solid-state drives (also called flash
hard drives). These are faster and more durable than hard disk drives, but
they are also more expensive.
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A USB flash drive is basically a small, removable flash hard drive that
plugs into a USB port. These are a convenient way to bring your files
with you and open them on a different computer.
If you're using Windows, you can view information about your
computer's RAM and processor speed without opening your computer.
Just go to the Control Panel (in the Start menu) and click System
and Security. In Mac OS X, you can view this information by clicking
the Apple icon and selecting About This Mac.
Expansion cards
Most computers have expansion slots on the motherboard that allow you
to add various types of expansion cards. These are sometimes called PCI
(peripheral component interconnect) cards. You may never have to add
any PCI cards, as most motherboards have built-in video, sound, network,
and other capabilities. However, if you want to boost the performance of
your computer or update the capabilities of an older computer, you can
always add one or more cards. Below are some of the most common types
of expansion cards:
Video card
A video card
The video card is
responsible for what you see
on the monitor. Most
computers have a GPU
(graphics processing unit)
built into the motherboard,
instead of having a separate
video card. If you like playing graphics-intensive games on the computer,
you can add a faster video card to one of the expansion slots to get better
Sound card
The sound card, also called an audio card, is responsible for what you
hear in the speakers or headphones. Most motherboards have integrated
sound, but you can upgrade to a dedicated sound card for higher-quality
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Network card
The network card allows your computer to communicate over a network
and access the Internet. It can either connect with an Ethernet cable or
through a wireless connection (often called Wi-Fi). Many motherboards
have built-in network connections, and a network card can also be added to
an expansion slot.
Bluetooth card
A Bluetooth dongle
Bluetooth is a technology for wireless communication
over short distances. It's often used in computers to
communicate with wireless keyboards, mice, and
printers. It's often built into the motherboard or
included in a wireless network card. For computers that don't have
Bluetooth, a USB adapter (called a dongle) can be purchased.
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