(^316) PC Hardware: A Beginner’s Guide
Elementary Electronics
Now that you know something about electricity, you can move onto some basic electron-
ics. This section contains a series of definitions and concepts that provide you with some
background on electronics. Don’t worry, this discussion is basic and is intended to act
only as an orientation.Digital Circuit
An electronic circuit that accepts and processes binary data using the rules of Boolean
algebra(AND,OR,XOR,andNOT)isadigitalcircuit.Adigitalcircuitismadeupofoneor
more electronic components that are placed in a series and work cooperatively to realize
the circuit’s logical objective. The objective of the circuit might be to compare one data
value to another, to move data from one location to another, or to add two numbers to-
gether. Whatever the objective, the components designed into the circuit determine
exactly what the circuit is capable of doing. Remember that the circuit is actually dealing
with low-voltage electrical values the entire time.Semiconductors, Conductors, and Insulators
Aconductor,such as copper and gold, carries, or conducts, an electrical current. Aninsulator,
such as rubber, doesn’t carry an electrical current, which is why a copper wire conductor
is usually wrapped with a rubber insulator. In between a conductor and an insulator is a
semiconductor. A semiconductor is neither a conductor or an insulator but can be altered
electrically to be one or the other. Charging a semiconductor with electricity or
high-intensitylightwilltoggleittoeitheraconductororasemiconductor—whateveritis
not at the time it is zapped. Think of a semiconductor as an electronic component that has
a switch on it that selects how it behaves.Electronic Building Blocks
Nearly all electronic circuits in a PC are built from just four basic electronic components,
including a fifth basic electronic component made from these four components. Each of
the four components has a specific function and makes a different contribution to a
circuit. These components are as follows: Resistor A resistor slows down the flow of electrical current in a circuit,
much like a funnel slows down a flow of water.
Capacitor A capacitor stores an electrical charge. A PC has some very large
capacitors, each of which has enough of an electrical charge to seriously injure you
or worse, such as the capacitors in the monitor and power supply. However, there
are also several levels of smaller capacitors used in the circuits on the PC.