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Copyright 2006 by The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill Technology Education

McGraw-Hill Technology Education Copyright 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

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Copyright 2006 by The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill Technology Education

Chapter 5A

Transforming Data IntoInformation

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5A-3

How Computers Represent Data

Number systemsA manner of counting

Several different number systems exist

Decimal number system Used by humans to count

Contains ten distinct digits

Digits combine to make larger numbers

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5A-4

How Computers Represent Data

Binary number system Used by computers to count

Two distinct digits, 0 and 1

0 and 1 combine to make numbers

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5A-5

How Computers Represent Data

Bits and bytes Binary numbers are made of bits

Bit represents a switch

A byte is 8 bits Byte represents one character

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5A-6

How Computers Represent Data

Text codes Converts letters into binary

Standard codes necessary for data transfer

ASCII American English symbols

Extended ASCII

Graphics and other symbols

Unicode

All languages on the planet

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ASCII

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How Computers Process Data

The CPU Central Processing Unit

Brain of the computer

Control unit Controls resources in computer

Instruction set

Arithmetic Logic unit (ALU)

Includes Registers (High Speed MemoryLocation built in CPU)

Arithmetic Unit: Simple math operations (+, -, , , ^)

Logic Unit: (=, , >, , < , , etc.)

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How Computers Process Data

Machine cycles Steps by CPU to process data

Instruction cycle (CPU gets the instruction)

Fetching

Decoding

Execution cycle (CPU performs the instruction)

Executing

Storing

Billions of cycles per second Pipelining processes more data

Multitasking allows multiple instructions (Threads)

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How Computers Process Data

Memory Stores open programs and data

Small chips on the motherboard

More memory makes a computer faster

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How Computers Process Data

Nonvolatile memory Holds data when power is off

Read Only Memory (ROM)

Basic Input Output System (BIOS) Power On Self Test (POST)

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How Computers Process Data

Volatile memory Requires power to hold data

Random Access Memory (RAM)

Data in RAM has an address CPU reads data using the address

CPU can read any address

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5A-13

Components affecting Speed

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5A-14

Affecting Processing Speed

Registers Number of bits processor can handle

High Speed Memory Location built in CPU

Word size Larger indicates more powerful computer

Increase by purchasing new CPU

32 bit / 64 bit

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5A-15

Affecting Processing Speed

Virtual RAM Computer is out of actual RAM

File that emulates RAM

Computer swaps data to virtual RAM Least recently used data is moved

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5A-16

Affecting Processing Speed

The computers internal clock Quartz crystal

Every tick causes a cycle

Speeds measured in Hertz (Hz) Modern machines use Giga Hertz (GHz)

billions of cycles per second

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5A-17

Affecting Processing Speed

The bus Electronic pathway between components

Expansion bus connects to peripherals

System bus connects CPU and RAM Bus width is measured in bits

Speed is tied to the clock

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5A-18

Affecting Processing Speed

External bus standards Industry Standard Architecture (ISA)

Local bus

Peripheral control interface (PCI)Accelerated graphics port (AGP)

Universal serial bus (USB)

IEEE 1394 (FireWire) PC Card

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5A-19

Affecting Processing Speed

Universal Serial Bus (USB) Connects external devices

Hot swappable

Allows up to 127 devices Cameras, printers, and scanners

http://en.wikipedia.org/wiki/Image:USB_Icon.svg

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Affecting Processing Speed

PC Card Used on laptops

Hot swappable

Devices are the size of a credit card

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5A-21

Affecting Processing Speed

Cache memory Very fast memory

Holds common or recently used data

Speeds up computer processing

Most computers have several caches;location depends on the CPU &Motherboard type

L1 holds recently used data (in CPU) L2 holds upcoming data (in CPU)

L3 holds possible upcoming data (inMotherboard)

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Copyright 2006 by The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill Technology Education

Chapter 5A

End of Chapter