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Computer Software

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CHAPTER 3 Computer Software THE STORED PROGRAM CONCEPT COMPUTER IS A BINARY SYSTEM PROGRAM: A set of instructions telling the computer what to do INSTRUCTION ... – PowerPoint PPT presentation

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Title: Computer Software


1
CHAPTER 3
  • Computer Software

2
THE STORED PROGRAM CONCEPT
  • COMPUTER IS A BINARY SYSTEM
  • PROGRAM A set of instructions telling the
    computer what to do
  • INSTRUCTION Individual step or operation in a
    program
  • MACHINE LANGUAGE Translated instruction
    understood by particular model of computer

3
EVOLUTION OF COMPUTER SOFTWARE
  • FIRST GENERATION Machine language - binary
    language designed for particular computer
  • SECOND GENERATION Assembly language -
    substituted mnemonic operation codes and
    addresses, translated to machine language by
    assembler

4
EVOLUTION OF COMPUTER SOFTWARE
  • THIRD GENERATION Procedural language - FORTRAN,
    COBOL, C - translated to machine language by
    compiler or interpreter. Example COBOL
  • FOURTH GENERATION Nonprocedural language. Tell
    what to do, not how to do it, order not
    important. Translate to machine language by
    compiler or interpreter. Example FOCUS

5
KEY TYPES OF SOFTWARE
  • APPLICATION SOFTWARE Programs written to
    accomplish particular tasks for computer users
  • SUPPORT SOFTWARE Programs that support
    application software in producing needed output.
    Does not directly produce output needed by users

6
APPLICATION SOFTWARE
  • WORD PROCESSING
  • SPREADSHEETS
  • DATABASE MANAGEMENT SYSTEMS
  • PRESENTATION GRAPHICS

7
APPLICATION SOFTWARE
  • WORLD WIDE WEB BROWSERS
  • ELECTRONIC MAIL, GROUPWARE
  • DESKTOP PUBLISHING
  • APPLICATION SUITES

8
SUPPORT SOFTWARE
  • OPERATING SYSTEMS Helps maximize work done,
    eases workload of users
  • JOB CONTROL LANGUAGE Allows users to communicate
    with operating systems
  • MULTIPROGRAMMING Large computers can run
    multiple programs simultaneously. Time-driven
    approach is time-sharing

9
SUPPORT SOFTWARE
  • MULTITASKING Allows small computers to work on
    several programs interactively
  • VIRTUAL MEMORY Allows computer to run portions
    of a large program as required, saving use of
    main memory
  • MULTIPROCESSING Multiple CPUs divide workload,
    increases efficiency

10
SOURCES OF OPERATING SYSTEMS
  • PROPRIETARY Written for particular computer
    class or system. Examples Windows 98, Windows
    2000
  • OPEN SYSTEM Not tied to specific platform.
    Examples UNIX, Linux
  • NETWORK OPERATING SYSTEM (NOS) Manages network
    resources, local area networks

11
GRAPHICAL USER INTERFACE (GUI)
  • MOUSE A standard pointing device
  • ICON Graphic or label on screen associated with
    task or operation
  • 32-BIT OPERATING SYSTEM Operating system handles
    32 bits at a time
  • CLICKING MOUSE ON ICON INITIATES TASK

12
OBJECT-ORIENTED PROGRAMMING (OOP)
  • COMPUTER PROGRAMMING BASED ON CREATING, USING SET
    OF OBJECTS Object combines data and methods (or
    chunks of programs)
  • EXAMPLES C, Smalltalk, Java

13
OTHER LANGUAGES
  • NATURAL LANGUAGES User types in or speaks
    English, computer evolves program
  • HYPERTEXT MARKUP LANGUAGE (HTML) Code used to
    develop World Wide Web (WWW) pages and sites
  • eXtensible Markup Language (XML) Used for data
    exchange on WWW

14
DATABASE MANAGEMENT SYSTEM (DBMS)
  • SUPPORT SOFTWARE USED TO CREATE, MANAGE, AND
    PROTECT ORGANIZATIONAL DATA
  • DBMS Software that manages a database, works
    with operating system to store and modify data
    and to make data accessible in authorized ways

15
TYPES OF DBMSs
  • HIERARCHICAL Data arranged in a top-down,
    organization chart fashion
  • NETWORK Data arranged like cities on a highway
    systems, often with multiple paths between pieces
    of data
  • RELATIONAL Data arranged into simple tables, and
    records are related by storing common data in
    each of the associated tables

16
FILING METHODS
  • INDEXED SEQUENTIAL ACCESS METHOD (ISAM)
  • EACH RECORD IDENTIFIED BY KEY
  • GROUPED IN BLOCKS AND CYLINDERS
  • KEYS IN INDEX
  • VIRTUAL STORAGE ACCESS METHOD (VSAM)
  • MEMORY DIVIDED INTO AREAS INTERVALS
  • DYNAMIC FILE SPACE
  • VSAM WIDELY USED FOR RELATIONAL DATABASES
  • DIRECT FILE ACCESS METHOD

17
COMPONENTS OF DBMS
  • DATA DEFINITION LANGUAGE Defines data elements
    in database
  • DATA MANIPULATION LANGUAGE Manipulates data for
    applications
  • DATA DICTIONARY/DIRECTORY Formal definitions of
    all variables in database, controls variety of
    database contents

18
STRUCTURED QUERY LANGUAGE (SQL)
  • EMERGING STANDARD
  • DATA MANIPULATION LANGUAGE
  • FOR RELATIONAL DATABASES

19
ADVANTAGES OF RELATIONAL DBMS
  • NEW DATA ELEMENTS CAN EASILY BE ADDED AS NEW
    NEEDS ARISE
  • NEW RELATIONSHIPS CAN BE CREATED AS NEW
    QUERY/REPORTING NEEDS CHANGE
  • FEWER DATA CONSISTENCY PROBLEMS DUE TO LESS
    REDUNDANT DATA STORAGE
  • MORE USER FRIENDLY TOOLS

20
COMPUTER-AIDED SOFTWARE ENGINEERING (CASE)
  • HELPS AUTOMATE SOFTWARE DEVELOPMENT Used by
    computer professionals to help automate software
    development
  • MAY INCLUDE
  • upper-CASE (requirements definition and design)
  • lower-CASE (code generation)
  • I-CASE or integrated-CASE

21
CHANGING NATURE OF SOFTWARE
  • MORE HARDWIRING OF SOFTWARE AND MORE MICROCODE
  • MORE COMPLEXITY OF HARDWARE/SOFTWARE ARRANGEMENTS
  • LESS CONCERN WITH MACHINE EFFICIENCY

22
CHANGING NATURE OF SOFTWARE
  • MORE PURCHASED APPLICATIONS AND MORE PORTABILITY
    OF THESE APPLICATIONS FROM ONE COMPUTER PLATFORM
    TO ANOTHER
  • MORE PROGRAMMING USING OBJECT-ORIENTED AND VISUAL
    LANGUAGES, IN LARGE PART BECAUSE OF EMPHASIS ON
    GUIs

23
CHANGING NATURE OF SOFTWARE
  • MORE EMPHASIS ON APPLICATIONS THAT RUN ON
    INTRANETS AND THE INTERNET
  • MORE USER DEVELOPMENT
  • MORE USE OF PERSONAL PRODUCTIVITY SOFTWARE ON
    MICROCOMPUTERS, ESPECIALLY PACKAGES WITH A GUI

24
CHAPTER 3
  • Computer Software
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