INFORMATION TECHNOLOGY IT INFRASTRUCTURE

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CHAPTER 5. THE ROLE OF SOFTWARE IN THE

• INFORMATION TECHNOLOGY (IT) INFRASTRUCTURE

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Learning Objectives

• Describe Major Types Of Software
• Examine System Software Operating Systems
• Explain Software Evolution
• Analyze Major Application Languages
• Describe Approaches To Software Development
• Identify Software Issues

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Management Challenges

• What Is Software?
• System Software
• Application Software
• New Software Tools, Approaches
• Managing Software Assets

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Software

• Detailed Instructions To Control Computer
  Operation
• Program Set Of Instructions To The Computer
• Stored Program Must Be In Primary Storage
• System Software Manages Computer Resources
• Application Software Specific Business
  Application

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Software
Application Software
System Software
Hardware
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Multiprogramming
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Multitasking

• Multiprogramming
• On A
• Single-user System
• Such As A
• Microcomputer

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Virtual Storage

• Method Of Handling Several Programs In Primary
  Storage
• Program Divided Into
• Fixed Length Portions (Pages) Or
• Variable Length (Segments)
• Current Portions Reside In Primary Storage
• Portions Swapped Out When Done

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Time Sharing

• Many Users Share Large Cpu
• TIME IN CPU DIVIDED INTO SLICES (E.G. 2
  Microseconds)
• Each User Has Access To Cpu During Slice
• Since Cpu Is Fast, Can Do Much During Time Slice
• Users Job Swapped Out At End Of Slice

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Multiprocessing

• Two Or More Parallel Processors In System
• PROGRAM CAN BE DIVIDED TO BE PROCESSED BY
  MULTIPLE Cpus
• Can Process Large Programs More Rapidly

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Language Translation

• Source Code High-level Language Instructions
• Compiler Translates High-level Code Into Machine
  Language
• Object Code Translated Instructions Ready For
  Computer

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Translation Process
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Graphical User Interface (GUI)

• Operating System Uses
• GRAPHIC ICONS (Icons, Buttons, Bars, Boxes)
• Mouse To Issue Commands
• Make Selections

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Microcomputer Operating Systems
OPERATING SYSTEM
FEATURES

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Microcomputer OPERATING SYSTEMS
OPERATING SYSTEM
FEATURES
Unix
For powerful Microcomputers, Workstations,
Minicomputers. Multitasking Multi-user
Processing Networking. Portable to various
Computer Platforms
Linux
Free, reliable alternative to Unix, Windows. Runs
on many Platforms
Mac OS
For Macintosh computers. Multitasking. Powerful
Graphics Multimedia
DOS
For IBM (PC-DOS) and PC (MS-DOS). Program
Memory 640K
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Generations Of Programming Languages

• 1st. Since 1940s. MACHINE LANGUAGE Binary Code
• 2nd. Since Early 50s. ASSEMBLY LANGUAGE
  Mnemonics For Numeric Code
• 3rd. Since Mid 50s. High-level Languages
• 4th. Since Late 70s. Modern Application
  Packages

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High-level Languages

• FORTRAN (Formula Translator) Scientific,
  Engineering Applications
• COBOL (Common Business Oriented Language)
  Predominant For Transaction Processing
• BASIC (Beginners All-purpose Symbolic Instruction
  Code) General Purpose PC Language

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High-level Languages

• PASCAL Used to teach structured programming
  practices. Weak in file handling, input / output
• C and C Powerful PC Language for developing
  applications. Efficient execution cross
  platform. C is object oriented

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Fourth Generation Languages (4GL)

• Can Be Employed By End Users
• Nonprocedural
• Can Develop Applications Quickly
• Natural Languages
• Six Categories

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FOURTH GENERATION Languages (4GL)

• 1. Query Languages
• rapidly retrieve data
• interactive/ on-line
• may use NATURAL LANGUAGE
• support special requests for data from relational
  databases

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Fourth Generation Languages (4GL)

• 2. Report Generators
• Create customized reports
• Wide range of formats
• 3. Graphics Languages
• Can manipulate drawings, graphs, photos, videos
• Presentation managers

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Fourth Generation Languages (4GL)

• 4. Application Generators
• User specifies computer needs
• Generator creates logic and code for application
• Greatly reduces development time

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Fourth Generation Languages (4GL)

• 5. Very High-level Programming Languages
• Professional programmer productivity tool
• Uses fewer instructions
• Reduces development time

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Fourth Generation Languages (4GL)

• 7. Software Package Commercially Available Set
  Of Programs...
• Word Processing
• Spreadsheets
• Data Management
• Presentation Management
• INTEGRATED SOFTWARE PACKAGES NOW COMBINE THESE TO
  SIMPLIFY LEARNING AND Use

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Software Tools

• Word Processing
• Spreadsheets
• Data Management
• Presentation Graphics
• Integrated Software Suites
• E-mail
• Web Browsers
• Groupware

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Object-oriented Programming

• Combines Data Procedures Into A Single Object
• Program Sends Message To Object To Perform
  Embedded Procedure
• Objects Data Encapsulated From Rest Of System
• Creates Reusable Code
• Reduces Time And Cost Of Writing Software

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Object-oriented Programming

• Visual Programming Select And Arrange Objects
  Rather Than Write Code
• Class All Objects Of A Class Have All Features
  Of That Class
• Inheritance Specific Class Receives Features Of
  A More General Class
• OVERRIDE Subclass May Oveerride Inherited Method
  (E.G. Printout Of An HOURLY Worker Pay Check May
  Differ From That Of A WEEKLY Worker

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Object-oriented Programming

• JAVA Sun Microsystems OBJECT-ORIENTED
  PROGRAMMING LANGUAGE
• Applet Tiny Program To Execute Small Function
• Applets Downloaded From Network
• Run On Any Computer Operating System
• Result Saved On Network, Not On Pc
• Only Network Version Of Software Needs Upgrade

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Object-oriented Programming

• Activex Controls For Windows Software
  Environment To Enable OBJECTS E.G.,
• Charts
• Tables
• Animations
• To Be Embedded In A Web Page

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Selecting Organizational Software

• Appropriateness
• Efficiency
• Compatibility
• Support

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Connect To The INTERNET
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