Chapter 02 m

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Today and Tomorrow 12th Edition

Understanding Computers

Chapter 2

The System Unit:

Processing and Memory

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Chapter 2 Understanding Computers, 12th Edition 2

Data and Program Representation• In order to be understood by a computer, data and

programs need to be represented appropriatey• Coding systems! Used to represent numeric, te"t#

based, and mutimedia data, as we as to representprograms

• Digita computers! Can ony understand two states, o$$and on %& and 1'

• Digita data representation! The process o$representing data in digita $orm so it can be used by acomputer

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Chapter 2 Understanding Computers, 12th Edition (

Digita Data Representation• )it! The smaest unit o$ data

that a binary computer canrecogni*e %a singe 1 or &'

• )yte + bits

• )yte terminoogy used to

e"press the si*e o$documents and other $ies,programs, etc-

• Pre$i"es are o$ten used toe"press arger .uantities o$bytes! /iobyte %0)',megabyte %)', gigabyte%)', etc-

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The )inary 4umbering 5ystem• 4umbering system! 6 way o$ representing numbers

• Decima numbering system

7 Uses 1& symbos %'

• )inary numbering system

7 Uses ony two symbos %1 and &' to represent apossibe numbers

• In both systems, the position o$ the digits determinesthe power to which the base number %such as 1& or 2'is raised

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The )inary 4umbering 5ystem

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Chapter 2 Understanding Computers, 12th Edition :

Coding 5ystems $or Te"t#)ased Data

• 65CII and E)CDIC

7 65CII %6merican 5tandard Code $or In$ormationInterchange'! coding system traditionay used withPCs

7 E)CDIC %E"tended )inary#Coded Decima

Interchange Code'! de;eoped by I), primariy $ormain$rame use

• Unicode! newer code %(2 bits per character iscommon'< uni;ersa coding standard designed to

represent te"t#based data written in any anguage

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Coding 5ystems $or Te"t#)ased Data

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Coding 5ystems $or >ther

Types o$ Data• 6udio data! ust be in digita $orm in order to be

stored on or processed by a PC 7 >$ten compressed when sent o;er the Internet

• P( $ies

• ?ideo data! Dispayed using a coection o$ $rames,each $rame containing a singe graphica image

7 6mount o$ data can be substantia, but can becompressed

• PE#2 $ies

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Representing Programs! achine

@anguage• achine anguage! )inary#based anguage $or

representing computer programs the computer cane"ecute directy

7 Eary programs were written in machine anguage-

7 TodayAs programs sti need to be transated into

machine anguage in order to be understood by thecomputer

• ost program are written in other programminganguages

7 @anguage transators are used to transate theprograms into machine anguage

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Inside the 5ystem Unit

• 5ystem unit! The main case o$ a computer

7 Bouses the processing hardware $or a computer

7 6so contains memory, the power suppy, cooing$ans, and inter$aces to connect periphera de;ices

7 Bouses the dri;e bays in which storage de;ices%hard dri;es, D?D dri;es, etc-' are ocated

7 ith a des/top PC, usuay oo/s i/e a rectanguarbo"

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Inside the 5ystem Unit

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The otherboard• Computer chip! 6 ;ery sma pieces o$ siicon or other

semi#conducting materia onto which integratedcircuits are embedded

• Circuit board! 6 thin board containing computer chipsand other eectronic components

• otherboard or system board! The main circuit boardinside the system unit

7 6 computer components must connect to themotherboard

7 E"terna de;ices %monitors, /eyboards, mice,

printers' typicay connect by pugging into a porte"posed through the e"terior o$ the system unit

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The CPU

• Centra processing unit %CPU'! circuitry and

components pac/aged together and attached to themotherboard

7 Does the ;ast maority o$ processing $or acomputer

7 6so caed a processor< caed a microprocessorwhen ta/ing about PCs

• Dua#core CPU! Contain the processing components%cores' o$ two separate processors on a singe CPU

• uad#core CPU! Contains 3 cores• Typicay designed $or des/top PCs, portabe PCs, or

ser;ers

• >$ten made by Inte or 6D

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The CPU

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Processing 5peed

• CPU coc/ speed! >ne measurement o$ processing

speed 7 easured in megahert* %B*' or gigahert* %B*'

7 Bigher CPU coc/ speed + more instructionsprocessed per second

• 6ternate measure o$ processing speed is the numbero$ instructions a CPU can process per second

7 ega$ops, giga$ops, tera$ops

• >ther $actors %CPU architecture, memory, bus speed,

etc-' aso a$$ect the o;era processing speed o$ acomputer

• )enchmar/ tests! Can be used to e;auate o;eraprocessing speed

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ord 5i*e and Cache emory• ord si*e! The amount o$ data that a CPU can

manipuate at one time 7 Typicay (2 or :3 bits

• Cache memory! 5pecia group o$ ;ery $ast memorychips ocated on or cose to the CPU

7 @e;e 1 is $astest, then @e;e 2, then @e;e (

7 ore cache memory typicay means $asterprocessing

7 Usuay interna cache today

)us idth )us 5peed and

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)us idth, )us 5peed, and

)andwidth• )us! 6n eectronic path o;er

which data can tra;e• )us width! The number o$

wires in the bus o;er whichdata can tra;e

• )us width and speeddetermine the throughput %orbandwidth' o$ the bus

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emory

• R6 %random access memory'! Temporary memory

that the computer uses 7 Consists o$ chips connected to a memory modue

which is connected to the motherboard

7 5I, DI, RI

7 Bods data and program instructions whie they areneeded-

7 6de.uate R6 is needed to run programs

7 ?oatie! Contents o$ R6 is ost when thecomputer is shut o$$

7 5ome $orms o$ non;oatie R6 are underde;eopment

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emory

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emory

• Registers! Bigh#speed memory buit into the CPU<

used by the CPU• R> %read#ony memory'! Read#ony chips ocated on

the motherboard into which data or programs ha;ebeen permanenty stored

7 Retrie;ed by the computer when needed

7 )eing repaced with $ash memory

• Fash memory! Type o$ non;oatie memory that canbe erased and reprogrammed

7 5ome $ash memory chips are used by the PC

7 Fash memory chips are aso used in $ash memorystorage media %stic/s, cards, and dri;es'

Fans Beat 5in/s and

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Fans, Beat 5in/s, and

>ther Cooing Components• Beat! 6 continuing probem $or CPU and computer

manu$acturers• Fans! Used on most PCs

• Beat sin/s! 5ma components typicay made out o$auminum with $ins that hep to dissipate heat

• ater cooing systems! Coo the PC with i.uid#$iedtubes

• >ther cooing methods %such as ion pump cooingsystems' are under de;eopment

Fans Beat 5in/s and

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Chapter 2 Understanding Computers, 12th Edition 2(

Fans, Beat 5in/s, and

>ther Cooing Components

E"pansion 5ots E"pansion Cards

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E"pansion 5ots, E"pansion Cards,and E"pressCards

• E"pansion card! 6 circuit board used to add additiona

$unctionaity or to attach a periphera de;ice• E"pansion sot! 6 ocation on the motherboard into

which e"pansion cards are inserted

• E"pressCard modues! Designed $ornoteboo/ computer e"pansion

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)uses

• )us! 6n eectronic path within a computer o;er which

data tra;es 7 5ystem bus! o;es data bac/ and $orth between

the CPU and memory

7 E"pansion buses! Connect the CPU to periphera%typicay input and output' de;ices

• PCI and PCI E"press %PCIe' bus

• 6P bus

• ByperTransport bus

• Uni;ersa 5eria )us %U5)'

• FireireGIEEE 1(83 bus

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Chapter 2 Understanding Computers, 12th Edition 2:

)uses

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Chapter 2 Understanding Computers, 12th Edition 2=

Ports and Connectors

• Port! 6 connector on the e"terior o$ a PCAs system unit

to which a de;ice may be attached

7 5eria

7 Parae

7 4etwor/

7 0eyboardGouse

7 onitor %?6,

D?I, BDI' 7 odemGPhone

7 U5)

7 Fireire

7 5C5I

7 IDI

7 IrD6

7 ame 7 e56T6

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• any des/top PCs come

with a ;ariety o$ ports onthe $ront o$ the systemunit $or easy access

• 6 wired or wireess hubcan connect manyde;ices to a singe U5)or Fireire port

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Chapter 2 Understanding Computers, 12th Edition (&


• 4oteboo/ computers

ha;e ports simiar todes/top PCs, but o$tennot as many

• Bandhed computers andmobie de;ices typicayha;e ess ports

7 6n 5D sot iscommon $or bothmemory cards

and to connectperiphera de;ices

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Chapter 2 Understanding Computers, 12th Edition (1

Bow the CPU or/s

• CPU! Consists o$ a ;ariety o$ circuitry and

components pac/aged together 7 Transistor! 0ey eement o$ the microprocessor

• ade o$ semi#conductor materia that acts i/e aswitch controing the $ow o$ eectrons inside a

chip• TodayAs CPUs contain hundreds o$ miions o$

transistors< the number doubes about e;ery 1months %ooreAs @aw'

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Typica CPU Components

• 6rithmeticG@ogic Unit %6@U'! Per$orms integer

arithmetic and ogica operations• Foating Point Unit %FPU'! Per$orms decima arithmetic

• Contro unit! Coordinates and contros acti;ities

• Pre$etch unit! Tries to $etch data and instructions

be$ore they are needed

• Decode unit! Transates instructions so they are

understood by the contro unit, 6@U, and FPU

• Interna cache and registers! 5tore data and

instructions needed by the CPU

• )us inter$ace unit! here data and instructions $ow in

and out o$ the CPU

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Chapter 2 Understanding Computers, 12th Edition ((

Typica CPU Components

The 5ystem Coc/ and the achine

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The 5ystem Coc/ and the achineCyce

• 5ystem coc/! Timing mechanism within the computer

system that synchroni*es the computerAs operations 7 Each signa is a cyce

7 4umber o$ cyces per second + hert* %B*'

7 any PC system coc/s run at 2&& B*

7 Computers can run at a mutipe or $raction o$ thesystem coc/

• For instance, with a CPU coc/ speed o$ 2 B*,the CPU coc/ Htic/s 1& times during each

system coc/ tic/ 7 During each CPU coc/ tic/, one or more pieces o$

microcode are processed


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• achine cyce! The series o$ operations in;o;ed in

the e"ecution o$ a singe machine e;e instruction 7 Fetch! The program instruction is $etched

7 Decode! The instructions are decoded so thecontro unit, 6@U, and FPU can understand them

7 E"ecute! The instructions are carried out

7 5tore! The origina data or the resut $rom the 6@Uor FPU e"ecution is stored either in the CPUAsregisters or in memory, depending on the

instruction


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Chapter 2 Understanding Computers, 12th Edition (:



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Chapter 2 Understanding Computers, 12th Edition (=


a/ing Computers Faster and )etter

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Chapter 2 Understanding Computers, 12th Edition (

a/ing Computers Faster and )etter4ow and in the Future

• Impro;ing per$ormance today

7 6dd more memory 7 Per$orm system maintenance

• Uninsta programs propery

• Consider pacing arge $ies on e"terna storage

de;ices• Deete temporary $ies

• 6rrange $ies e$$icienty

• 5can $or ;iruses and spyware

• Empty the Recyce )in 7 )uy a arger or second hard dri;e

7 Upgrade your Internet connection

7 Upgrade your ;ideo graphics card

a/ing Computers Faster and )etter

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a/ing Computers Faster and )etter4ow and in the Future

• 5trategies $or $aster and better computers

7 Impro;ed architecture! 5maer components, $asterbus speeds, mutipe CPU cores, etc-

7 Impro;ed materias! 4ew bac/ing materias, $e"ibecircuits, etc-

7 Pipeining! 6ows mutipe

7 instructions to be processed

7 at one time

7 utiprocessing and parae

7processing! Use mutipe 7 processors to speed up processing

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Chapter 2 Understanding Computers, 12th Edition 3&

Pipeining

P P i

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Parae Processing

F t T d

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Future Trends• 4anotechnoogy! The science o$ creating tiny

computers and components ess than 1&&nanometers in si*e

• Carbon nanotubes used in many products today

• 4anopartices and nanocrystas

• In the $uture, components may be buit bywor/ing at the indi;idua atomic and moecuare;es

F t T d

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Chapter 2 Understanding Computers, 12th Edition 3(

Future Trends

• uantum computing! 6ppies the

principes o$ .uantum physics and.uantum mechanics to computers

7 Utii*es atoms or nucei wor/ingtogether as .uantum bits%.ubits'

7 ubits $unction simutaneousyas the computerAs processorand memory and can representmore than two states

7 E"pected to be used $orspeciai*ed appications, suchas encryption and codebrea/ing

F t T d

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Future Trends

• >ptica computer! Uses ight, such as $rom aser

beams or in$rared beams, to per$orm digitacomputations

7 >pto#eectronic computers use both optica andeectronic components

• 5iicon photonics! The process o$ ma/ing opticade;ices using siicon manu$acturing techni.ues

7 Bybrid siicon aser

• Terascae computing! The abiity to process one triion

$oating#point operations per second 7 E"pected to be needed $or $uture appications

• (D chips! Contain transistors that are ayered to cutdown on the sur$ace area re.uired

5

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5ummary

• Data and Program Representation

• Inside the 5ystem Unit

• Bow the CPU or/s

• a/ing Computers Faster and )etter 4ow and Inthe Future

Chapter 02 m

Documents

Transcript of Chapter 02 m