4/3/2009
1
Chapter 16
Inside the Computer โ
Transistors and Integrated Circuits
Electricity and Switches
๎modern computers are powered by electricity, using
electrical signals to store and manipulate information
๎the components of a computer require electrical power
to carry out their assigned task
๎electricity generates the light that shines through a
computer screen, illuminating the individual pixels that
make up images and letters
๎electricity runs the motor that spins the hard-drive disk,
allowing information to be accessed
๎main memory and CPU employ electrical signals to store
and manipulate data
๎bit patterns are represented by the presence or absence of
electrical current along a wire
Electricity Basics
๎electricity is a flow of
electrons,
the negatively charged
particles in atoms, through a medium
๎good conductors of electricity allow for t he flow of electrons
with little resistance (e.g., copper, silver, gold)
๎other elements, especially nonmetals, are poor conductors
(e.g., carbon, oxygen)
Electricity Basics
๎electricity can be quantified in
amperes
or
voltage
๎
ampere
s gauge electron flow: 1 amp is equal to 6.24
quintillion (1018) electrons flowing past a given point each
second
๎
voltage
measures the physical force produced by the flow of
electrons: standard household in United States has 110 to
120 volt outlets
Electricity Basics Switches
๎the most basic tool for controlling the flow of electricity
is a
switch
๎a switch can be flipped to connect or disconnect two wires,
thus regulating the flow of electricity between them
