Technology in Action

Chapter 6Behind the Scenes:

A Closer Look at System Hardware

Chapter Topics Computer switchesBinary number systemASCII / UnicodeCreating faster CPUs

Data RepresentationProcess of transforming diverse data into a

form computers can use for processingDigital devices work with distinct and

separate dataAnalog devices work with continuous data

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Digital vs. AnalogAnalog Signals Have an Infinite Number of

ValuesDigital Signals Have a Discrete Number of

ValuesIn this case, the Analog Wave ranges from 0-1Note that the Digital Wave is Either 0 or 1

(nothing between)

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Representing Numbers We normally use the

decimal numbering system, which uses 10 symbols (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9).

Computers use the binary numbering system, which represents all numbers using just two symbols (0 and 1).

Everything a computer does is broken down into a series of 0s and 1s, stored with switches

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Switches Representing DataThe on/off state of a switch represents one bit

of dataBit (binary digit)

On = 1Off = 0

OFF

0

ON

1

01

OR = 1 bit

The Binary Number SystemDescribes a number as powers of 2Also referred to as base 2 numbering

systemUsed to represent every piece of data

stored in a computer: all of the numbers, letters, and instructions

Chapter 2: Computer Hardware8

The Binary Number SystemNumber systems are organized ways to represent

numbersEach number in one system has a corresponding

number in another.

1282x64

642x32

322x16

162x8

82x4

42x2

22x1

1

Binary 0 1 0 1 1 0 0 1

Base 10

0 + 64 + 0 + 16 + 8 + 0 + 0 + 1 = 89

01011001 = 89 Binary Base 10

Representing Letters and SymbolsAmerican Standard Code for Information Interchange

(ASCII)8 bits = 1 byte = alphanumeric character or symbol256 different combinations

Unicode16 bits = 2 bytes = one symbol65,000 different combinations, used for all languagesNOT a translator program!

01100001 = a

01000001 = A

00100011 = #

01101101 = m

ASCII

ASCII Chart

ASCII

Chapter 2: Computer Hardware12

Microprocessor Performance FactorsSerial Processing

All Activities are Done on One CPUPipelining Processes Independent Tasks

SimultaneouslyOverall Job Finishes Earlier

Example: If you have 4 sets of laundry to wash, dry, and fold…Do you completely finish one load then start

another?

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Serial Processing

Pipelining

Microprocessor Performance FactorsParallel Processing

The tasks are divided among multiple CPUsIn previous example, would be like having

multiple washer/dryer setsModern Dual Core Processors actually contain

all the circuitry for two separate microprocessors

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