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OCR for page 14
:mpwessor
: ...... .
.. ~ ....~. ~. ~
.. ~. ~.~. ~
.mtcroprocessor- a tiny
....................... .
~nputer on a chip no
..............
tiger than your fingernail
room. At work, they help
design complex buildings and
control huge manufacturing
has quickly and quietly machines. In between, they
infiltrated our lives since it coordinate traffic lights and
was introduced in 1971. At improve fuel efficiency in cars.
home, microprocessors are the And everywhere there is a
A web of electronic
circuitry spreads across the
face of the 4004, the first
microprocessor. The chip
contains 2,300 transistors yet
measures only '/s inch by '/~
inch, about the size of a
child's fingernail.
4
personal computer, there is a
· e
microprocessor c turning
· ~
away 1nslc e.
brains in electronic devices
that control microwave
ovens and change television
channels from across the
A microprocessor works something like
a juke box's record player, which plays the
tune on a record retrieved from its collection.
A microprocessor, however, plays the set of
instructions retrieved from a memory chip,
performing simple functions such as
addition or subtraction programmed into
the instructions. Microprocessor and memo-
ry chips alike rely on microscopic integrated
circuits to perform their tasks.
Before microprocessors, integrated
circuit chips were generally not
programmable. They could do only a single
function for which they were designed, like a
record player playing one tune engraved on
its turntable. The first microprocessor, in fact,
was developed by an American engineer
who was given the task of designing 12
single-function chips for a Japanese calcula-
tor. Instead, the engineer designed one
general-purpose chip that performed all 12
functions according to instructions stored in
a memory chip. Because each instruction
c ontained only four bits-the electronic l's
E N G I N E E R I N G A N D T H E A D V A N C E M E N T O F H U M A N W E L F A R E
OCR for page 15
and O's of digital code the microprocessor
was classified a 4-bit chip.
Microprocessors of the first generation
were too feeble to power anything resem-
bling a personal computer. But they
were and still are powerful enough to
drive pocket calculators and control
machines performing simple tasks. They
have become, like the motor, a tool for every
use. Millions are sold each year to operate
home burglar alarms, remote television
controllers, programmers for videocassette
recorders, and dozens of toys. The "~bitter"
was the hottest selling microprocessor every
year until 1988, when 8-bit chips took the
lead.
Microprocessor chips in a variety of sizes
provide the delicate control that improves
the efficiency of power plants, cars, and
heating and cooling systems in buildings,
which translates into lower operating costs
and less pollution. They are also widely used
in the cockpits of advanced commercial
airliners to control navigation and other
avionics systems, thereby improving the
efficiency of aircraft and crew.
Second-generation microprocessors-
the mighty 8-bit chips that appeared in
1974 had enough calculating power to
operate low-performance computers. These
"microcomputers" were built around
microprocessors and remained curiosities,
the electronic playthings of hobbyists, until
MICROPROCESSOR
Microprocessors are the
tiny "brains" inside
microcomputers and hundreds
of other electronic devices.
15
OCR for page 16
Microprocessors make modern
airliners easier to fly by
displaying flight instrument
data on video screens, as in
the cockpit of this advanced
747. These data display
screens and other design
improvements helped reduce
the number of cockpit lights,
switches, and gauges to fewer
than 400 in this aircraft
compared with nearly 1,000
in earlier models.
~ ,~.1
............... : i,,,l
--- 1-1
Small, inexpensive personal
computers built around
microprocessors bring
computer power into
millions of homes around the
world. Ready-to-use programs
have made it easy for children
as well as adults to use these
computers for video games,
word processing, and dozens
of other applications.
6
the introduction of third-generation chips in
1975. These delivered much better perfor-
mance than their forerunners and brought
down microprocessor prices to as low as $25
from nearly $200. Within two years, they
spawned commercial lines of home micro-
computers that were soon being used for
nonhome tasks.
It was, however, the fourth generation-
mostly the powerful 16-bit microprocessors-
that convinced the traditional computer
industry that microcomputers based on these
chips were powerful enough for more than
home video games. And in 1981 the main-
frame-computer industry began marketing
microcomputers for such computational
tasks as graphics, desktop publishing,
managing large data bases, and computer-
aided design in business and industry.
Microcomputers would have been
useless without software, the programs of
simple commands that tell computers how to
perform complex tasks. Each computer has
coded operating instructions already wired
into it, but they are awkward for people to
use. So the codes have been translated into
languages, such as BASIC, FORTRAN, and
COBOL, based on easy-to-use words and
symbols. The languages further simplify
programming by using single symbols for
some simple functions that are generated by
a series of instructions. For example, "a"
might trigger the series of instructions for the
function "multiply". The languages, in turn,
are used to program larger sets of instruc-
tions, or programs, that perform complex
tasks such as word processing. For instance,
word processing software might be pro-
grammed so that typing C-O-P-Y initiates
the thousands of instructions for duplicating
a page of text on the computer screen.
Software was not readily available for
the earliest microcomputers. Hobbyists
labored to compose their own operating
systems programs telling a computer how
to run itself and application programs for
tasks such as word processing or playing
Space Invaders. However, a cottage industry
of programmers began to sprout in the mid-
1970s and was soon turning out commercial
programs for a multitude of applications,
including word processing, video games,
inventory control, and personal finance
management.
The combination of ready-made soft-
ware and low-cost microcomputers pro-
duced the true personal computer, a machine
so affordable and easy to use that it was
available to almost everyone. The impact has
been enormous. PCs have done for comput-
ing power what the printing press did for
knowledge gave it to the masses. Connect-
ed by telephone lines, PC users tap into
networks of computers as well as into data
banks for stock quotations, medical informa-
tion, and legal cases. In the future they may
be able to draw on data bases of library
books, newspapers, and magazines from all
over the world.
I E N G ~ N E E R ~ N G A N ~ T H E ~ D VA N C E M E N T O F H U M A N W E ~ FA R E
OCR for page 17
Today's microprocessors greatly outper-
form their 4-bit ancestors. One 32-bit chip, for
example, is a thousand times faster. Another
carries 500 times more transistors, packing 1
million of them onto a chip no bigger than a
postage stamp. Others made by a process
called CMOS, for complementary metal-
oxide semiconductor use less energy and
produce less heat than conventional chips.
They are used in satellites, portable comput-
ers, and other devices where energy con-
sumption is critical. The speed of some
microprocessor chips has been improved by
a design known as RISC, or reduced instruc-
tion set computer, which uses a small
number of simple instructions. Complex
instructions, which occur infrequently, are
handled in software. Larger memory chips
have also been developed to hold the
complex programs that exploit the power of
the new microprocessors.
In the future, multipurpose microproces-
sor chips will probably grow to 64 bits, some
containing as many as 10 million transistors.
Application-specific processors will be
designed for just a few specific tasks. Such
chips are faster and more efficient at a single
job than a chip designed to do everything.
The key to making application-specific
processors will be advanced computer-aided
design (CAD) systems themselves based
on microprocessor chips that design such
specialized chips quickly and inexpensively.
The new microprocessors and the
systems they run will have the power to
generate better graphics and higher-quality
three-dimensional images for CAD systems.
Microcomputers, for example, will certainly
be more adept at human talents, such as
understanding spoken words, speaking, or
even learning and reasoning artificial
intelligence. And they will be able to process
incredible amounts of data at lightning
speeds. Work is under way on a new genera-
tion of supercomputers, which would link
hundreds, even thousands, of m~croproces-
sors in parallel arrays. Each chip would work
on a different part of a massive problem, such
as a global weather forecast, solving the entire
problem in a fraction of the time needed if
each part were solved one after the other. The
challenge of parallel-array systems is to
develop mathematical formulas and operat-
ing systems to coordinate the work of all the
microprocessors.
An even greater challenge lies in figur-
ing out how to take best advantage of the
wonderfully powerful computers based on
these new microprocessors. That is the task
of the programmers, whose work is limited
only by their ability to think creatively.
The i486 microprocessor
squeezes 1.18 million
transistors-500 times
mare than the 'I.
MICROPROCESSOR
I microprocessor-onto a chip
about the size of an adult's
thumbnail.
17
Representative terms from entire chapter:
microprocessor chips
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