18 Computer Service and Repair
by several brightly-colored wires that supply the
electrical energy needed to run the hard drive
system.
Motherboard
The motherboard is usually a rectangular
piece of circuit board covered with many
conductors that provide electrical energy paths
to the computer components and expansion slots,
Figure 1-26. It provides a way to distribute the
digital signals carrying data, control instructions,
and small amounts of electrical power to the many
different components mounted on the board. The
electrical system of pathways is referred to as the
computer bus.
RAM
Random access memory (RAM) is where
computer programs are loaded to from the hard
drive, Figure 1-27. RAM is classified as a volatile
memory system. Volatile simply means that the
data and programs loaded in RAM are lost when
power is turned off. Increasing a computer’s RAM
is one of the most common computer upgrades
performed. RAM is usually mounted into several
parallel slots on the motherboard. The amount of
RAM in a typical home PC could be 4 GB or more.
Depending on the type of applications to be run,
the amount of RAM required will vary.
RAM is a place where data is temporarily
stored. When a computer is turned off, the RAM
is emptied. When a computer is started, new
information is loaded into RAM. When you draw
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Figure 1-24. The power supply converts 120 Vac input to a
much lower dc output required by the computer components.
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Figure 1-25. Hard drives are the most common storage
device used with a PC.
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Figure 1-26. Almost all computer data runs through the
motherboard.