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Computer Software

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HIERARCHICAL: Data arranged in a top-down, organization chart fashion ... DATA DICTIONARY/DIRECTORY: Formal definitions of all variables in database, ... – 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
KEY TYPES OF SOFTWARE
  • APPLICATION SOFTWARE Programs written to
    accomplish particular tasks for computer users
  • SUPPORT SOFTWARE or SYSTEM SOFTWARE Programs
    that support application software in producing
    needed output. Does not directly produce output
    needed by users

4
Spheres of Influence Application Software
  • Two or more people who work together to achieve
    a
  • common goal
  • Systems that support information sharing, group
  • scheduling, group decision making, and
    conferencing

Workgroup
Personal
Enterprise
  • programs that support
  • the firm in its
  • interaction with its
  • environment
  • order entry, billing
  • programs that serve the
  • needs of an individual user
  • word processing,
  • spreadsheets, databases,
  • e-mail

5
Application Software General-Purpose vs.
Application-Specific
  • General-purpose application programs programs
    that perform common information processing jobs
    for end users
  • Examples include
  • Word processing
  • Spreadsheet
  • Database management
  • Graphics
  • Web browsers
  • Electronic mail
  • Groupware
  • Application-specific programs that direct the
    processing required for a particular use
  • Examples include
  • Business Applications - accounting, sales
    management, eCommerce
  • Science and Engineering Applications research
    and development
  • Personal Applications
  • Education and Entertainment Applications

6
Web Browsers
7
Application Suites
  • Software suites are a combination of the most
    widely used productivity packages that come
    bundled together
  • Suites integrate software packages for web
    browsing, word processing, spreadsheets,
    presentation graphics, database management,
    personal information management, and more
  • Examples Microsoft Office, Lotus SmartSuite, and
    Corel WordPerfect Office

8
Groupware helps teams work together to accomplish
group assignments
  • Groupware products (Lotus Notes, Novell
    GroupWise, Microsoft Exchange, Netscape
    Communicator) support collaboration through
  • Electronic Mail
  • Discussion groups and databases
  • Scheduling
  • Task management
  • Data, audio, and videoconferencing
  • Internet, corporate intranets and extranets to
    make collaboration possible on a global scale by
    virtual teams located anywhere in the world.
  • Joint web page development
  • Publish project news and progress reports
  • Working jointly on documents stored on web servers

9
EVOLUTION OF PROGRAMMING LANGUAGE
  • 1st Generation Machine language - binary
    language designed for particular computer
  • 2nd Generation Assembly language - substituted
    mnemonic operation codes and addresses,
    translated to machine language by assembler
  • 3rd Generation Procedural language - FORTRAN,
    COBOL, C - translated to machine language by
    compiler or interpreter. Example COBOL
  • 4th 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

10
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

11
HTML, XML and Java
  • HTML and Java have become vital tools for
    building multimedia web pages, web sites, and
    web-based applications
  • HTML is a page description language that creates
    hypertext or hypermedia documents
  • XML describes the contents of web pages by
    applying identifying tags or contextual labels to
    the data in web documents
  • Java
  • is an object-oriented programming language
  • is computing platform independent
  • Is designed for realtime, interactive, web-based
    network applications
  • Java applications consist of small application
    programs called applets, which can be executed by
    any computer and any operating system anywhere in
    a network

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
Categories of Programming Languages
14
Programming Language Translation
15
Programming Languages Terminology
  • Language translator
  • Systems software that converts a programmers
    source code into its equivalent in machine
    language.
  • Source code
  • High-level program code written by the
    programmer.
  • Object code
  • Another name for machine language code.

48
16
SUPPORT (SYSTEMS) 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
  • 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

17
Functions of an Operating System
18
OPERATING SYSTEMS a set of programs that control
the hardware and acts as an interface with
application programs
19
User Interface
  • User Interface
  • A function of the operating system that allows
    individuals to access and command the computer.
  • Command-Based User Interface
  • A particular user interface that requires text
    commands be given to the computer to perform
    basic activities.
  • Graphical User Interface (GUI)
  • A user interface that uses pictures (icons) and
    menus displayed on the screen to send commands to
    the computer system.

20
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

21
Software Concepts
  • Virtual Memory
  • Memory that allocates space in secondary storage
    to supplement the immediate, functional memory
    capacity of RAM.
  • Paging
  • A function of virtual memory that allows the
    computer to store currently needed pages in RAM
    while the rest of these programs wait in
    secondary storage.

22
Utility Programs
  • merge and sort sets of data,
  • keep track of computer jobs being run,
  • compress files of data before they are stored or
    transmitted over a network, and
  • perform other important tasks.

23
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

24
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

25
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

26
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

27
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

28
Database (Access / Approach / Paradox) Stores,
manipulates, and retrieves data
(Figure 4.10)
28
29
STRUCTURED QUERY LANGUAGE (SQL)
  • EMERGING STANDARD
  • DATA MANIPULATION LANGUAGE
  • FOR RELATIONAL DATABASES

30
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

31
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

32
CHANGING NATURE OF SOFTWARE
  • MORE HARDWIRING OF SOFTWARE AND MORE MICROCODE
  • MORE COMPLEXITY OF HARDWARE/SOFTWARE ARRANGEMENTS
  • LESS CONCERN WITH MACHINE EFFICIENCY
  • MORE PURCHASED APPLICATIONS AND MORE PORTABILITY
    OF THESE APPLICATIONS FROM ONE COMPUTER PLATFORM
    TO ANOTHER

33
CHANGING NATURE OF SOFTWARE
  • MORE PROGRAMMING USING OBJECT-ORIENTED AND VISUAL
    LANGUAGES, IN LARGE PART BECAUSE OF EMPHASIS ON
    GUIs
  • 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

34
Trends in Computer Software
Trend Toward Easy-to-Use Multipurpose
Network-Enabled Application Packages for
Productivity and Collaboration
User-written programs Machine languages
Packaged programs Symbolic languages
Operating systems High-level languages
DBMS Fourth-generation languages Microcomputer
packages
Natural object- oriented languages Multipurpos
e graphic-interface network-enabled
expert-assisted packages
Trend Toward Visual or Conversational
Programming Languages and Tools
35
CHAPTER 3
  • Computer Software
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