16 Computer Service and Repair
commands into actions, such as save the data on
the screen to memory, open a new file, and locate
a file.
As discussed earlier, the CPU does not think
or possess any human intelligence as some movies
may depict. A CPU simply carries out the program
codes written in the software program.
Power Supply
The power supply converts the 120-volt ac
power from the wall outlet to dc voltage levels
used by the various computer components,
Figure 1-24. Once the 120 volts of ac power is
converted to a lower dc voltage, usually 3.3, 5,
or 12 volts, cables carry the electrical energy to
the motherboard, hard drive, and other major
components.
Hard Drive
The hard drive (also called the internal drive
or hard disk drive) is where computer programs
and data are stored, Figure 1-25. A hard drive is
made up of several disks in a stack inside a sealed
box. Computer programs and data are stored
on the hard drive as magnetic patterns. Data is
transmitted to and from the hard drive through
a data cable attached to the hard drive on one
end and to the motherboard on the opposite end.
The hard drive is connected to the power supply
familiarize you with the exterior connections. Be
sure you can visually identify each port type.
Take a Tour Inside the
Computer Case
The inside of a PC is filled with a number
of standard components and expansion slots
that allow each computer to be customized
with a tremendous variety of interesting tools,
Figure 1-22. The equipment that follows details
only the common computer components. These
are devices you will find in almost every system.
CPU
In the simplest of terms, the central
processing unit (CPU) is the brain of the
computer, Figure 1-23. Intel® Core® i7, Intel®
Pentium®, Intel® Celeron®, AMD FX 8-Core, and
AMD Phenom™ identify various models of CPUs.
The CPU consists of millions of microscopic
electronic components called transistors. The
transistors are electrically connected together in
such a way they are able to interact with computer
programs and process data.
All the other computer components depend
on the actions of the CPU. The CPU controls the
data in the computer. Commands are issued to
the CPU via software. The CPU translates the
PS/2 keyboard/mouse
combination port IEEE-1394a RJ-45
USB 3.0 USB 2.0 USB 3.0 Audio I/O Power
eSATA
External
SATA
Goodheart-Willcox Publisher
Figure 1-21.
High-performance
motherboard with non-
standard connections.