Signals and Systems - Electrical Engineering

4 C H A P T E R 0: From the Ground Up!

processing, the trend has been toward digital representation and processing of data, most of which

are in analog form. Such a trend highlights the importance of learning how to represent signals in

analog as well as in digital forms and how to model and design systems capable of dealing with

different types of signals.

1948

The year 1948 is considered the birth year of technologies and theories responsible for the spectacular advances in com-

munications, control, and biomedical engineering since then. In June 1948, Bell Telephone Laboratories announced the

invention of the transistor. Later that month, a prototype computer built at Manchester University in the United Kingdom

became the first operational stored-program computer. Also in that year, many fundamental theoretical results were pub-

lished: Claude Shannon’s mathematical theory of communications, Richard W. Hamming’s theory on error-correcting codes,

and Norbert Wiener’sCyberneticscomparing biological systems with communication and control systems [51].

Digital signal processing advances have gone hand-in-hand with progress in electronics and comput-

ers. In 1965, Gordon Moore, one of the founders of Intel, envisioned that the number of transistors

on a chip would double about every two years [35]. Intel, the largest chip manufacturer in the world,

has kept that pace for 40 years. But at the same time, the speed of the central processing unit (CPU)

chips in desktop personal computers has dramatically increased. Consider the well-known Pentium

group of chips (the Pentium Pro and the Pentium I to IV) introduced in the 1990s [34]. Figure 0.1

shows the range of speeds of these chips at the time of their introduction into the market, as well as

the number of transistors on each of these chips. In five years, 1995 to 2000, the speed increased by

a factor of 10 while the number of transistors went from 5.5 million to 42 million.

FIGURE 0.1

The Intel Pentium CPU chips. (a) Range of

CPU speeds in MHz for the Pentium Pro

(1995), Pentium II (1997), Pentium III (1999),

and Pentium IV (2000). (b) Number of

transistors (in millions) on each of the above

chips. (Pentium data taken from [34].)

1995 1997 1999 2000

0

1000

2000

MHz

Year

(a)

(b)

1995 1996 1997 1998 1999 2000

10

20

30

40

Million transistors

Year