Hardware Reference
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everywhere and embedded in everything—indeed, invisible. They will be part of
the framework of daily life, opening doors, turning on lights, dispensing money,
and doing thousands of other things. This model, devised by Mark Weiser, was
originally called ubiquitous computing , but the term pervasive computing is also
used frequently now (Weiser, 2002). It will change the world as profoundly as the
industrial revolution did. We will not discuss it further in this topic, but for more
information about it, see Lyytinen and Yoo (2002), Saha and Mukherjee (2003),
and Sakamura (2002).
1.3 THE COMPUTER ZOO
In the previous section, we gave a very brief history of computer systems. In
this one we will look at the present and gaze toward the future. Although personal
computers are the best known computers, there are other kinds of machines around
these days, so it is worth taking a brief look at what else is out there.
1.3.1 Technological and Economic Forces
The computer industry is moving ahead like no other. The primary driving
force is the ability of chip manufacturers to pack more and more transistors per
chip every year. More transistors, which are tiny electronic switches, means larger
memories and more powerful processors. Gordon Moore, co-founder and former
chairman of Intel, once joked that if aviation technology had moved ahead as fast
as computer technology, an airplane would cost $500 and circle the earth in 20
minutes on 5 gallons of fuel. However, it would be the size of a shoebox.
Specifically, while preparing a speech for an industry group, Moore noticed
that each new generation of memory chips was being introduced 3 years after the
previous one. Since each new generation had four times as much memory as its
predecessor, he realized that the number of transistors on a chip was increasing at a
constant rate and predicted this growth would continue for decades to come. This
observation has become known as Moore's law . Today, Moore's law is often
expressed as the doubling of the number of transistors every 18 months. Note that
this is equivalent to about a 60 percent increase in transistor count per year. The
sizes of the memory chips and their dates of introduction shown in Fig. 1-8 con-
firm that Moore's law has held for over four decades.
Of course, Moore's law is not a law at all, but simply an empirical observation
about how fast solid-state physicists and process engineers are advancing the state
of the art, and a prediction that they will continue at the same rate in the future.
Some industry observers expect Moore's law to continue to hold for at least anoth-
er decade, maybe longer. Other observers expect energy dissipation, current leak-
age, and other effects to kick in earlier and cause serious problems that need to be
 
 
 
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