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Introduction to Information Technology, 2ndEditionTurban, Rainer & Potter

2003 John Wiley & Sons

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Introduction to Information Technology

2ndEdition

Turban, Rainer & Potter

2003 John Wiley & Sons, Inc.

Computer Software

Prepared by:

Roberta M. Roth, Ph.D.

University of Northern Iowa


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Chapter Preview

In this chapter, we will study:

Systems Software

Application SoftwareHow software applications are developed

How software has evolved and where its

headed

Software for the enterprise


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The Software Crisis

New software

applications cannot be

developed fast enough to:

Keep up with dynamicbusiness environment

Keep pace with rapid

hardware advances

Lag in software

development limits IScapabilities

Computer System

Hardware Software


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The Software Crisis(continued)

In addition to new application development,

existing software must also be maintained (80%IT personnel effort towards maintenance).

Increasing complexity leads to the increased

potential for bugs.

Testing and debugging software is expensive

and time-consuming.


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Software Fundamentals

Some basic terms

Computer programs - sequences of instructions forthe computer

Stored program conceptinstructions written inprograms are stored and executed by CPU when

needed

Programming - process of writing (or coding)

programs

Programmers - individuals who performprogramming


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Software Fundamentals (continued)

Systems Software

Instructions that

manage the hardware

resources

Application Software

Instructions that

perform specific user

tasks

Computer Software

Systems

Software

Application

Software

Makes thecomputerfunction

Doessomethinginteresting


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System Software

System software is software that:

Controls and supports the computer systems

activities

Supports application software by directing the

computers basic functions

Facilitates program development, testing, and

debuggingIs independent of any specific type of

application


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Systems Software (continued)

System ControlPrograms

Control use of all

system resources(hardware, software,data); operatingsystem

System Support

Programs

Specialized supportcapabilities

Systems Software

SystemControl

Programs

SystemsSupport

Programs


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System Control Programs

Operating System - main system control

program

supervises the overall operation of thecomputer

allocates CPU time and main memory to

programs running on the computer

provides an interface between the user and

the hardware


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Operating System Services

Process management manage program(s) runningon processor

Multitasking or Multiprogramming -managing two ormore tasks, or programs, running on the computer system at the

same timeMultithreading type of multitasking; run two or more tasks

from the same application simultaneously

Timesharing -many users share same CPU, each using adifferent input/output terminal

Multiprocessingsimultaneous processing with multiple CPUs


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Operating System Services (continued)

Virtual memory - simulates more main memory thanactually exists in the computer system

File management and security - managing thearrangement of, and access to, files held in secondary

storage

Fault tolerance - system can produce correct results andcontinue to operate even in the presence of faults or errors

User interface - allows users to have direct control ofvisible objects (icons) and actions that replace complexcommand syntax


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Major Desktop Operating Systems

Types of Operating Systems

MS-DOS

Windows 95 Windows 98

Windows NT Windows 2000

Microsoft Products:

Windows XP

Windows ME

Macintosh Operating System

UNIX

Java Operating System (JavaOS)

Other Products: Linux

IBM O/S 2


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Departmental Server Operating Systems

Support hundreds of concurrent users

UNIX, Linux, Windows 2000, Windows XP,

Novell NetWare

Enterprise Operating Systems

Support thousands of concurrent users; millions

of transactions per dayIBMs OS/390, IBMs VM (Virtual Machine),

IBMs VSE (Virtual Storage Extended), andIBMs OS/400

Types of Operating Systems (continued)


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Support the operations, management, and

users of a computer system

Examples:

System Utilities

Perform common tasks: sorting records, checking

disk integrity, creating directories and

subdirectories, restoring accidentally erased files,

locating stored files, managing memory usage, and

redirecting output.

System SupportPrograms


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Examples (continued)

Performance monitors

monitor job processing

produce statistical reports on system resource usage

Security monitors

monitor the use of a computer system to protect it

and its resources from unauthorized use, fraud, ordestruction

System SupportPrograms (continued)


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Application Software

Programs performing specific information

processing activities and user functionality

Types of Application Software

Proprietary application software Addresses a specific or unique business need for a company

Off-the-shelf application software

Vendor developed programs sold to many organizations

May be standardpackage or may be customizable


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2003 J h Wil & S

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Application Software (continued)

Spreadsheets

Data management

Word processing

Desktop publishing

GraphicsPresentation; Analysis;

CAD

Multimedia

Communication

Speech-recognition

Groupware

Personal Application Software- off-the-shelfapplication programs supporting general types of processing

Documents

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