Unit 4Fundamentals of Computer Processing;Fundamentals of Computer Processing;

The Database and The Database and Database Management System;Database Management System;

&&Data CommunicationsData Communications

1-1

Chapter 8Fundamentals of Fundamentals of

Computer ProcessingComputer Processing

8-2

Computing HistoryComputing History ENIAC - 1946ENIAC - 1946 UNIVAC IUNIVAC I

– First sold in 1956 to Census Bureau First sold in 1956 to Census Bureau IBM System 360 Line of ComputersIBM System 360 Line of Computers

– 1960’s 1960’s – Revolutionized computingRevolutionized computing

1954 -- first computer installed in a business 1954 -- first computer installed in a business (another UNIVAC I at GE)(another UNIVAC I at GE)

8-3

Computing HistoryComputing History Early 1970s -- minicomputersEarly 1970s -- minicomputers Late 1970s -- microcomputers (TRS-80, Late 1970s -- microcomputers (TRS-80,

Commodore PET)Commodore PET) IBM PC IBM PC

– 19821982

8-4

Computer SizesComputer Sizes Mainframes Mainframes

– LargeLarge– Centrally locatedCentrally located– Used by large organizationsUsed by large organizations

Minicomputers Minicomputers – Mid-sizedMid-sized– Today’s server market descended from these Today’s server market descended from these

machinesmachines

8-5

Computer Sizes [cont.]Computer Sizes [cont.] Microcomputers Microcomputers

– Made possible by microprocessorMade possible by microprocessor– PC -- used by one person, or by a few people in the same PC -- used by one person, or by a few people in the same

areaarea

8-6

LiteracyLiteracy Computer LiteracyComputer Literacy

– Ability to use computing resourcesAbility to use computing resources Information LiteracyInformation Literacy

– Understanding how and why information Understanding how and why information affects the decision-making processaffects the decision-making process

8-7

Control Unit

Arithmetic and Logic Unit

Primary Storage Unit

Central Processing Unit(CPU)

TheComputerSchematic

Input Data OutputInformation

SecondaryStorage

Unit

8-8

ProcessorsProcessors Main unit where processing is performedMain unit where processing is performed

– Called CPUCalled CPU– Microcomputer CPUs called microprocessorsMicrocomputer CPUs called microprocessors

SpeedSpeed– Moore’s LawMoore’s Law– Megahertz (MHz)Megahertz (MHz)– Word SizeWord Size

8-9

MemoryMemory Main memoryMain memory

– Storage area where both data being processed Storage area where both data being processed and program instructions being executed are and program instructions being executed are storedstored

Storage (secondary)Storage (secondary)– Magnetized coding on the surface of a storage Magnetized coding on the surface of a storage

devicedevice

8-10

Bits and BytesBits and Bytes One kilobyte (1KB) One kilobyte (1KB)

– 221010 bytes (1,024) bytes (1,024) One megabyte (1MB) One megabyte (1MB)

– 222020 bytes (1,048,576) bytes (1,048,576) One gigabyte (1GB) One gigabyte (1GB)

– 223030 bytes (1,073,741,924) bytes (1,073,741,924)

8-11

Different Memory TypesDifferent Memory Types RAM - Random access memoryRAM - Random access memory

– Computer programs and data are loaded into RAM to Computer programs and data are loaded into RAM to be executed by the computer processorbe executed by the computer processor

ROM - Read-only memoryROM - Read-only memory– Information used by the operating system and Information used by the operating system and

processor when the computer is startedprocessor when the computer is started DRAM - Dynamic RAMDRAM - Dynamic RAM

– Allows buffering of data and increases efficiency of Allows buffering of data and increases efficiency of RAMRAM

8-12

Different Memory Types Different Memory Types (cont.)(cont.)

SDRAM - Synchronous DRAMSDRAM - Synchronous DRAM– Runs much faster than most conventional memory Runs much faster than most conventional memory

because it synchronizes its cycles with the processor’s because it synchronizes its cycles with the processor’s cyclescycles

SIMM - Single in-line memory moduleSIMM - Single in-line memory module– Holds 9 memory chips and transmits 32 bits of data Holds 9 memory chips and transmits 32 bits of data

per cycleper cycle DIMM - Dual in-line memory moduleDIMM - Dual in-line memory module

– Transmits 64 bits per data cycleTransmits 64 bits per data cycle

8-13

Storage DevicesStorage Devices Tape or disk driveTape or disk drive Sequential storageSequential storage Random storageRandom storage High CapacityHigh Capacity

– DVD, CD-ROM, CD-RW, Zip, JazDVD, CD-ROM, CD-RW, Zip, Jaz

8-14

Removable Disks and their Removable Disks and their Storage CapacitiesStorage Capacities

3.5 inch floppy disks holds 1.44 MB of dataZip disk may hold 100MB or 250MB of dataJaz disk holds 2GB of dataCD disk holds 650MB of dataDVD disk holds 5GB to 20GB of data

8-15

Input DevicesInput Devices KeyboardsKeyboards MicrophonesMicrophones Machine-captured dataMachine-captured data

– Scanners/barcodesScanners/barcodes– Cost benefitsCost benefits

8-16

Output DevicesOutput Devices DisplayedDisplayed

– MonitorMonitor» ResolutionResolution» PixalsPixals» GUIGUI

– CGA, EGA, VGA, SVGACGA, EGA, VGA, SVGA PrintedPrinted

– SpeedSpeed– QualityQuality– Impact/nonimpactImpact/nonimpact

8-17

Microfilm

Computer

ABC123

Plotters

Speech OutputDevices

Printers

Displayed OutputDevices

Means ofProducin

g Compute

rOutput

8-18

PrintersPrinters

Impact Nonimpact

Line Character

Dotmatrix

Daisywheel

Page LaserInkjet

8-19

MultimediaMultimedia Use of more than one media at one timeUse of more than one media at one time

– ImageImage– VideoVideo– AudioAudio

Pointing devicesPointing devices Speech synthesisSpeech synthesis Animated imagesAnimated images

8-20

Hardware ChangesHardware Changes Power compared to price doubles every 18 Power compared to price doubles every 18

monthsmonths Cultivate new information about computing Cultivate new information about computing

resourcesresources– Trade journalsTrade journals– Professional societiesProfessional societies– Continuing educationContinuing education– WWWWWW

8-21

SoftwareSoftware Two main types of software -- system and Two main types of software -- system and

applicationapplication SystemSystem

– Performs fundamental tasks that all users of a Performs fundamental tasks that all users of a particular computer requireparticular computer require

ApplicationApplication– Processes user’s dataProcesses user’s data

8-22

Three Main System Three Main System Software TypesSoftware Types

Operating systemOperating system– Manages computer’s processesManages computer’s processes

» Schedule tasksSchedule tasks» Manage hardware and software resourcesManage hardware and software resources» Maintain system securityMaintain system security» Enable sharing Enable sharing » Handle InterruptsHandle Interrupts

8-23

Three Main System Three Main System Software Types(cont.)Software Types(cont.)

UtilitiesUtilities– Routine that enables the user to perform certain Routine that enables the user to perform certain

basic data processing activitiesbasic data processing activities– Copy, erase, sort, merge, et ceteraCopy, erase, sort, merge, et cetera

Language translatorsLanguage translators– Change programmer instructions into computer Change programmer instructions into computer

instructionsinstructions– Highest form for translation is a natural languageHighest form for translation is a natural language

8-24

System Software Types System Software Types (cont.)(cont.)

Fourth generation languagesFourth generation languages– Called 4GLCalled 4GL– Describes what is to be done by computerDescribes what is to be done by computer– Does not describe explicitly how it will be doneDoes not describe explicitly how it will be done– DBMSs are related to this areaDBMSs are related to this area

» SQLSQL» Query languageQuery language» SAS, SPSSSAS, SPSS

8-25

Source

Program

Translate

ObjectProgram

OutputInputData

The Program is Translated Before the Data is Processed

1

2

8-26

Application SoftwareApplication Software Prewritten softwarePrewritten software

– Standardized by business functionStandardized by business function– Also called packaged application software and Also called packaged application software and

off-the-shelf application softwareoff-the-shelf application software– AdvantagesAdvantages

» Available nowAvailable now» Less expensiveLess expensive

8-27

Application Software Application Software (cont.)(cont.)

Custom softwareCustom software– Best for unique business operationsBest for unique business operations– Far less is created today because of wide Far less is created today because of wide

availabilityavailability– Programmer salaries have risenProgrammer salaries have risen

8-28

Role of User-Friendly Role of User-Friendly SoftwareSoftware

Businesses need programmers to create Businesses need programmers to create applicationsapplications– EmployeesEmployees– ConsultantsConsultants– Contracts with other companiesContracts with other companies

Simple intuitive software is user-friendlySimple intuitive software is user-friendly Business users have expertise in their areasBusiness users have expertise in their areas

– Need to work with technical expertsNeed to work with technical experts

8-29

Software ChangeSoftware Change Software changes almost as rapidly as Software changes almost as rapidly as

hardwarehardware– IS professionals are routinely contacted IS professionals are routinely contacted

concerning system updatesconcerning system updates– Professional societies and conferencesProfessional societies and conferences

Changes in business needsChanges in business needs

8-30

SummarySummary HardwareHardware

– Processor, memory, storageProcessor, memory, storage– Input, manipulation, outputInput, manipulation, output

SoftwareSoftware– SystemsSystems– ApplicationApplication

Rapid changesRapid changes

8-31

Chapter 9The Database and Database The Database and Database

Management SystemManagement System

Copyright 2001 Prentice-Hall, Inc.

9-32

Data OrganizationData Organization Data FieldData Field

– Smallest unit of dataSmallest unit of data RecordRecord

– Collection of related fieldsCollection of related fields FileFile

– Collection of related recordsCollection of related records

9-33

Data Organization (cont.)Data Organization (cont.) FoldersFolders

– Collection of related filesCollection of related files– Conceptually similar to a branch of the treeConceptually similar to a branch of the tree

SubfolderSubfolder– A folder within a folderA folder within a folder

Movement of folders using GUIMovement of folders using GUI

9-34

Organization of Data into Organization of Data into FoldersFolders

9-35

Common Models for Common Models for Organizing Data FilesOrganizing Data Files

1. Function2. Frequency of Use3. Users4. Projects

9-36

Fundamental Building Fundamental Building Blocks for Database Blocks for Database

StructuresStructures1. Data Value2. Data Field3. Data Record4. Data File

9-37

Spreadsheet as a Simple Spreadsheet as a Simple DatabaseDatabase

Rows and columns of a spreadsheet can be Rows and columns of a spreadsheet can be regarded as a simple databaseregarded as a simple database

Flat filesFlat files– Does not have repeating columnsDoes not have repeating columns– Spreadsheet table is a file and column is a fieldSpreadsheet table is a file and column is a field

Key fieldsKey fields– Contains a value to uniquely identify each Contains a value to uniquely identify each

record in a tablerecord in a table

9-38

Data Structure vs. Data Structure vs. Spreadsheet TerminologySpreadsheet Terminology

Spreadsheet Term Data Structure Term

Table FileColumn FieldRow Record

9-39

Database StructuresDatabase Structures DatabaseDatabase

– All data stored on computer-based resources of All data stored on computer-based resources of the organizationthe organization

Database Management System (DBMS)Database Management System (DBMS)– Software application that stores the structure of Software application that stores the structure of

the database, the data itself, relationships the database, the data itself, relationships among the data in the database, as well as forms among the data in the database, as well as forms and reports pertaining to the databaseand reports pertaining to the database

9-40

Database Structures Database Structures (cont.)(cont.) Hierarchical structure Hierarchical structure

– Uses the ‘parent / children’ conceptUses the ‘parent / children’ concept– Limitation: Cannot handle ad hoc requestsLimitation: Cannot handle ad hoc requests– First DBMS was IDS by GE in 1964First DBMS was IDS by GE in 1964– CODASYLCODASYL

Network structureNetwork structure– Allow given record to point back to any other record in Allow given record to point back to any other record in

the databasethe database– Specification released by CODASYL in 1971Specification released by CODASYL in 1971– Solves problem of having to backtrack through dataSolves problem of having to backtrack through data

9-41

Database Structures Database Structures (cont.)(cont.)

Relational structureRelational structure– Rows and columnsRows and columns– Frees designers from need to specify Frees designers from need to specify

relationships prior to building the databaserelationships prior to building the database– Date and Codd described structureDate and Codd described structure– Does not rely on physical relationshipsDoes not rely on physical relationships– Easy to understandEasy to understand

9-42

Relational Database Relational Database VendorsVendors

1. IBM2. Informix Software, Inc.3. Microsoft4. Oracle5. Sybase

9-43

The Database ConceptThe Database Concept Database conceptDatabase concept

– Logical integration of records in multiple files Logical integration of records in multiple files Data redundancyData redundancy

– Duplication of dataDuplication of data Data inconsistencyData inconsistency Data independenceData independence

– Keep data specifications separate from Keep data specifications separate from programs, in tables and indexesprograms, in tables and indexes

9-44

TablesTablesBook Name Author Required

Banking Principles Knox 25Management Information Systems 8E McLeod and Schell 75 Personal Sales Techniques Wei 70Quality Service, Quality Customer Brutus 54

9-45

Description of Book TableDescription of Book Table

9-46

Description of Student Description of Student TableTable

9-47

Table RelationshipsTable Relationships

9-48

Salespersonfile

Salesstatistics

file

Customerfile

Accountsreceivable

file

Buyer file

Inventory file

Vendor file

Accounts payable file

Purchase order file

General ledger file

A Database Consists of One or More Files9-49

Evolution of Database Evolution of Database SoftwareSoftware

GE’s IDS first exampleGE’s IDS first example– Used with COBOLUsed with COBOL

IBM’s IMSIBM’s IMS– Apollo projectApollo project

Interface IssuesInterface Issues– Intel’s System 2000, RAMIS, IDMS, InquireIntel’s System 2000, RAMIS, IDMS, Inquire– Query language interfaceQuery language interface

9-50

Evolution of Database Evolution of Database Software (cont.)Software (cont.)

SEQEL from IBMSEQEL from IBM– Continuation of IMSContinuation of IMS

Renamed SQLRenamed SQL– Structured Query language Structured Query language – Embedded within traditional languageEmbedded within traditional language– StandaloneStandalone

PC database packagesPC database packages– dBase IIdBase II– MS-Access MS-Access

9-51

Creating a DatabaseCreating a Database Two approaches:Two approaches:

1. Process oriented approach (problem-1. Process oriented approach (problem-solving)solving)

2.2. Enterprise modelingEnterprise modeling

9-52

DefineDefinethe Problemthe Problem

Identify necessaryIdentify necessarydecisionsdecisions

DescribeDescribeinformation needsinformation needs

DetermineDeterminethe necessarythe necessary

processingprocessing

SpecifySpecifydata needsdata needs

1.1.

2.2.

3.3.

4.4.

5.5.

6.6.

Data NeedsData NeedsCan BeCan BeDefined by Defined by Taking a Taking a Problem-Problem-Oriented Oriented ApproachApproach

DataDataSpecificationsSpecifications

9-53

Createenterprisedata model

DevelopDatabase

Database

2.

1.

Strategic Planning for Information Resources

Data Needs CanBe Defined by

Creating an Enterprise

Model

EnterpriseData Model

9-54

Describing the Database Describing the Database ContentsContentsData dictionary

Enterdictionary data

Data descriptionlanguage (DDL)

Schema

Step 1

Step 2

9-55

SchemaSchema Data field nameData field name Aliases (other names used for same data Aliases (other names used for same data

field)field) Type of data (numeric alphabetic)Type of data (numeric alphabetic) Number of positionsNumber of positions Number of decimal positionsNumber of decimal positions Various integrity rulesVarious integrity rules

9-56

Rule for Required FieldRule for Required Field

9-57

Enforcing Value of Enforcing Value of BookNameBookName

9-58

Creating a DatabaseCreating a Database 1) Describe the data1) Describe the data 2) Enter the data2) Enter the data 3) Use the database3) Use the database

– Query languageQuery language– Query-by-exampleQuery-by-example– Data manipulation language (DML)Data manipulation language (DML)

9-59

Query-by-ExampleQuery-by-Example

9-60

On-Line Analytical On-Line Analytical Processing (OLAP)Processing (OLAP)

Feature to enable data analysis similar to Feature to enable data analysis similar to statistical cross-tabulationstatistical cross-tabulation

Information can be generated from within Information can be generated from within DBMSDBMS

No need for separate statistical softwareNo need for separate statistical software

9-61

Example OLAP OutputExample OLAP Output

Marital Status Married Single Cash $752 $849Payment Credit $1,277 $2,019Method Check $283 $165

9-62

The Database The Database Administrator (DBA)Administrator (DBA)

D B A DutiesD B A Duties Database planning; work with users and Database planning; work with users and

others, define schema, etc.others, define schema, etc. Database implementation; creating the Database implementation; creating the

database and enforcing policies and database and enforcing policies and proceduresprocedures

Database operationsDatabase operations Database securityDatabase security

9-63

DataDatadescriptiondescriptionlanguagelanguageprocessorprocessor

Database managerDatabase manager QueryQuery

languagelanguageData manipulationData manipulation

language (DML)language (DML)

Application programsApplication programs

DatabaseDatabasedescription description

(schema)(schema)

DatabaseDatabase

InformationInformation requests requests

InformationInformation

TransactionTransaction loglog

Backup/recoveryBackup/recoverymodulemodule

PerformancePerformancestatisticsstatistics

PerformancePerformance statisticsstatistics processorprocessor

PerformancePerformance statisticsstatistics

A DBMSA DBMSModelModel

9-64

Knowledge Discovery in Knowledge Discovery in Databases (KDD)Databases (KDD)

Data warehousingData warehousing– refinement in the database concept to make itrefinement in the database concept to make it

» very largevery large» very purevery pure» very retrievablevery retrievable

Data martData mart– a more modest approach than data a more modest approach than data

warehousing, generally only one segment of warehousing, generally only one segment of the firmthe firm

9-65

Knowledge Discovery in Knowledge Discovery in Databases (KDD) (cont.)Databases (KDD) (cont.)

Data miningData mining– the process of finding relationships in data the process of finding relationships in data

that are unknown to the userthat are unknown to the user– may be formay be for

» verificationverification» discoverydiscovery» combination of verification and discoverycombination of verification and discovery

9-66

The Knowledge Discovery The Knowledge Discovery in Database (KDD) Processin Database (KDD) Process

1. Define the data and the task1. Define the data and the task2. Acquire the data2. Acquire the data3. Clean the data3. Clean the data4. Develop the hypothesis and search model4. Develop the hypothesis and search model5. Mine the data5. Mine the data6. Test and verify6. Test and verify7. Interpret and use7. Interpret and use

9-67

DBMS AdvantagesDBMS Advantages Reduce data redundancyReduce data redundancy Achieve data independenceAchieve data independence Enable integration of data from multiple Enable integration of data from multiple

filesfiles Retrieve data and information quicklyRetrieve data and information quickly Improve securityImprove security

9-68

DBMS DisadvantagesDBMS Disadvantages

Obtain expensive softwareObtain expensive software Obtain a large hardware configurationObtain a large hardware configuration Hire and maintain a DBA staffHire and maintain a DBA staff

9-69

Requires a firm to:

SummarySummary Organizations are storing vast amounts of Organizations are storing vast amounts of

datadata Organization and structures in databaseOrganization and structures in database

– Dominated by relationalDominated by relational Staff positionsStaff positions

– DBADBA Knowledge discovery in databasesKnowledge discovery in databases Database management systemsDatabase management systems

9-70

Chapter 10Data CommunicationsData Communications

Copyright 2001 Prentice-Hall, Inc.

10-71

Communication BasicsCommunication Basics Computer communications is at Computer communications is at

three levelsthree levels– Application level Application level – Computer levelComputer level– Communication channelCommunication channel

Protocol Protocol – Set of rules for communicationsSet of rules for communications– OSI StandardOSI Standard

10-72

OSI Reference ModelOSI Reference ModelLayer Name Purpose

7 Application Layer Application-to-application communication 6 Presentation Layer Manage data representation conversions 5 Session Layer Establish and maintain communication channel 4 Transport Layer Guarantee end-to-end integrity of transmission 3 Network Layer Route data between network addresses 2 Data Link Layer Move data from one network address to another 1 Physical Layer Put data onto and off of the network media

10-73

ISO WebsiteISO Website

10-74

Protocols for Computer Protocols for Computer CommunicationCommunication

Early computersEarly computers– TerminalsTerminals– Sneaker netSneaker net

System Network Architecture (SNA)System Network Architecture (SNA)– Established by IBM in 1974Established by IBM in 1974– ProprietaryProprietary

Token-RingToken-Ring– Host computer controlledHost computer controlled– peer-to-peerpeer-to-peer

10-75

Protocols for Computer Protocols for Computer CommunicationCommunication

EthernetEthernet– Xerox working with Intel and Digital Xerox working with Intel and Digital

Equipment Corporation developed this protocolEquipment Corporation developed this protocol– Non-proprietaryNon-proprietary– Defined by IEEEDefined by IEEE– Works on a single transmission lineWorks on a single transmission line– No token is passedNo token is passed

10-76

PacketsPackets Piece of the total data to be communicated, Piece of the total data to be communicated,

combined with the address of the destination combined with the address of the destination computer for the data and other control computer for the data and other control information.information.

Transmission Control Protocol/Internet Protocol (TCP/IP) is one of the more important packet switching protocols

10-77

Network AddressesNetwork Addresses Address Address

– Four-part set of numbers Four-part set of numbers – Each from 0 to 255Each from 0 to 255

Internet Service Providers (ISPs)Internet Service Providers (ISPs)– User connects through common carrierUser connects through common carrier

Serial Line Internet Protocol (SLIP) and Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP)Point-to-Point Protocol (PPP)– Protocols for users at homeProtocols for users at home

10-78

Protocols for Public Phone Protocols for Public Phone SystemsSystems

X.25X.25– analoganalog– older protocololder protocol

Integrated Services Digital Network (ISDN)Integrated Services Digital Network (ISDN)– Digital Digital – Can carry voice, data, and videoCan carry voice, data, and video

10-79

Protocols for Public Phone Protocols for Public Phone Systems (cont.)Systems (cont.)

Frame RelaysFrame Relays– Move to fiber opticsMove to fiber optics

Asynchronous Transfer Mode (ATM)Asynchronous Transfer Mode (ATM)– Smaller packet sizeSmaller packet size– Faster transmission speedsFaster transmission speeds

10-80

Data Communications Links theData Communications Links theGeneral Systems Model ElementsGeneral Systems Model Elements

Standards

Management Informationprocessor

Environment

Input Transformation Output

10-81

NetworksNetworks Each device must be connected to the Each device must be connected to the

communications medium via a network communications medium via a network interface card (NIC)interface card (NIC)

10-82

Types of NetworksTypes of Networks LAN (local area network)LAN (local area network)

– Limited area but could include 100 or so microsLimited area but could include 100 or so micros– Facilitates office automationFacilitates office automation

MAN (metropolitan area networks)MAN (metropolitan area networks)– spans one city/metropolitan areaspans one city/metropolitan area

WAN (wide area network)WAN (wide area network)– Covers a large geographic areaCovers a large geographic area– Includes a wide variety of circuits Includes a wide variety of circuits – Usually includes host computersUsually includes host computers

10-83

UsersUsers

Manager 1Manager 1

Secretary 1Secretary 1

Secretary 2Secretary 2

WorkstationWorkstation11

WorkstationWorkstation22

WorkstationWorkstation33

WorkstationWorkstation44

Manager 2Manager 2

NetworkNetworkServerServer

HardHardDiskDisk

Letter QualityLetter QualityPrinterPrinter

PlotterPlotter

A Local Area NetworkA Local Area Network 10-84

Common LAN TopologiesCommon LAN TopologiesStarStar

10-85

Common LAN TopologiesCommon LAN TopologiesRingRing

10-86

Common LAN TopologiesCommon LAN TopologiesBusBus

10-87

SatelliteSatellite

EarthEarthstationstation

EarthEarthstationstation

TelephoneTelephonecompanycompanycentral officecentral office

TelephoneTelephonecompanycompanycentral officecentral office

TelephoneTelephonecompanycompanycentral officecentral office

TelephoneTelephonecompanycompanycentral officecentral office

LocalLocallooploop

User’sUser’smodemmodem

MicrowaveMicrowave towertower

MicrowaveMicrowave towertower

IXC circuitIXC circuit(interexchange(interexchange

channel)channel)

IXC circuit(interexchange channel)

LocalLocallooploop

Wide Area Wide Area NetworkNetwork

User’sUser’smodemmodem

10-88

Types of Networks (cont.)Types of Networks (cont.) InternetInternet

– Collection of networksCollection of networks– PublicPublic

IntranetIntranet– Uses Internet network protocolsUses Internet network protocols– Limits accessibilityLimits accessibility– FirewallFirewall

ExtranetExtranet– For trusted business partners and customersFor trusted business partners and customers

10-89

Control of Data Control of Data Communications NetworksCommunications Networks CentralizedCentralized

– Point-of-sale terminalsPoint-of-sale terminals– Data collection terminalsData collection terminals

Distributed processingDistributed processing– Receiving computer runs programs that use dataReceiving computer runs programs that use data

Client/server processingClient/server processing– Mixes centralized and decentralized processing Mixes centralized and decentralized processing

strategiesstrategies

10-90

Legend:

Computer Terminal

A Network of TerminalsA Network of Terminals

10-91

Legend:

CentralComputer

DistributedComputer

A Distributed Processing A Distributed Processing NetworkNetwork

10-92

Communications HardwareCommunications Hardware ModemModem

– Converts digital to analog and vice versaConverts digital to analog and vice versa– Bits per second determines transmission speedBits per second determines transmission speed– Local loopLocal loop

Hub Hub – Receives a data packet from a computer at one end of Receives a data packet from a computer at one end of

one spoke of the star topography and copies its contents one spoke of the star topography and copies its contents to all other computersto all other computers

– Manageable hubsManageable hubs

10-93

Data Communications with a Data Communications with a ModemModem

ComputerComputerModemModem ChannelChannel ModemModemComputerComputer

A modem is always required between a telephone and a digital computer

10-94

Communications Hardware Communications Hardware (cont.)(cont.)

RouterRouter– Device that connects many LANsDevice that connects many LANs– More sophisticated than a bridgeMore sophisticated than a bridge– Process header information of a packetProcess header information of a packet

SwitchSwitch– Filters data not intended for a computer on a Filters data not intended for a computer on a

particular networkparticular network

10-95

Communications Communications ConnectionsConnections

Private LinesPrivate Lines– Circuit that is always open to communications Circuit that is always open to communications

traffictraffic– Also called leased line or dedicated lineAlso called leased line or dedicated line– Two typesTwo types

» T-1 - Maximum speed just over 1.5 MbpsT-1 - Maximum speed just over 1.5 Mbps» T-3 - Maximum speed 43 MbpsT-3 - Maximum speed 43 Mbps» Collections of 64 Kbps connectionsCollections of 64 Kbps connections

10-96

Communications Communications Connections (cont.)Connections (cont.)

Virtual Private Networks (VPNs)Virtual Private Networks (VPNs)– Tunneling software makes Internet connections Tunneling software makes Internet connections

more securemore secure– Privacy through authenticationPrivacy through authentication– More cost effective than private linesMore cost effective than private lines

10-97

Network ManagementNetwork Management Digital nervous systems of an organizationDigital nervous systems of an organization Network planningNetwork planning

– Anticipates firm’s network needsAnticipates firm’s network needs– Monitor’s performanceMonitor’s performance

Network ControlNetwork Control– Determines faultsDetermines faults

» Errors in data communicationErrors in data communication» Alerts to potential faultsAlerts to potential faults

10-98

Network Management Network Management (cont.)(cont.)

Network managerNetwork manager– Planning, implementing, operating, and controlling a Planning, implementing, operating, and controlling a

firm’s data communications network(s)firm’s data communications network(s) StaffStaff

– Network analysts (a type of systems analyst)Network analysts (a type of systems analyst)– Software analysts Software analysts – Data Communication Technicians (specialize in Data Communication Technicians (specialize in

hardware)hardware)– LAN managersLAN managers

10-99

Wireless NetworksWireless Networks Cellular networksCellular networks

– Hand held telephonesHand held telephones– Primarily for voicePrimarily for voice

Wireless LANs Wireless LANs – Extensions of regular LANsExtensions of regular LANs

Wide-area wireless networksWide-area wireless networks– NationwideNationwide

10-100Highlights in MIS

Wireless Networks (cont.)Wireless Networks (cont.) Paging networksPaging networks

– Receive only capabilityReceive only capability

Personal Communications Network (PCN) is the networking infrastructure for wireless.

It is not yet in place!

10-101Highlights in MIS

A Network with Mobility A Network with Mobility CapabilityCapability

MSS = mobile support station MU = mobile units

MU MU MU

MU MU MU MU MU MU

MU MU MU

MSS

MSS MSS

MSS

Fixed host

Fixed host

Fixed host

Fixed host

Fixed network

10-102Highlights in MIS

SummarySummary Data communications enable computers to Data communications enable computers to

share information and applicationsshare information and applications NetworksNetworks

– LANsLANs– MANsMANs– WANsWANs

Communication standardsCommunication standards

10-103

Summary [cont.]Summary [cont.] Basic HardwareBasic Hardware

– HubsHubs– RoutersRouters– BridgesBridges– SwitchesSwitches

Planned growthPlanned growth

10-104