Transcript Lecture Notes

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Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
CHAPER 4
COMPUTER SOFTWARE
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Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
Learning Objectives
 Differentiate between the two major types of software
 Describe the general functions of the operating
system
 Differentiate among the three types of operating
systems and describe each type
 Identify three methods for developing application
software
 Describe the major types of application software
 Explain how software has evolved and its future
evolution
 Describe enterprise software
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Chapter Overview
Software History
and Significance
• The Software
Crisis
• Software
Fundamentals
Software
Issues
• Software
evaluation and
Selection
•Software Licensing
•Software Upgrades
•Shareware,
Freeware, and
Cheapware
•Open Systems
Systems
Application
Software
Software
• System Control
• Types of Application Software
Programs
• Types of Personal Application
• System Support
Software
Programs
• Software Suites
Programming
Enterprise
Languages
Software
• Machine Language
• Streamlining
• Assembly Language
Organizational
• Procedural Languages
Software
• Nonprocedural Languages
• SAP
• Natural Programming Language
• Visual Programming Language
• Hypertext Markup Language
• Virtual Reality Modelling Language
• Object-Oriented Programming
Language
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Case: The IRS and the Millennium Bug
 The Problem
 Y2K problem has resulted from the high
cost of mainframe computations and
data storage in the 1950s and 1960s
 complex structure makes it almost impossible for
the IRS to be Y2K compliant in time
 agency changed its software in response to changes
in the tax code
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Case (continued…)
 The Solution
 IRS has spent more than $4 billion over the past
decade to modernize its computer systems
 the agency has $1 billion dollars and 600 people
dedicated to the Y2K project
The Results
 no one will know until well into the year 2000
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Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
Case (continued…)
What have we learned from this case??
 Failure to budget for continuing
maintenance of software programs can
have devastating results
 One programmer cannot begin with his portion
of the problem until he receives another
completed portion form someone else, as this
other part or “module” may define the inputs or
outputs that his own part must deal with
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Turban, Rainer and Potter
Chapter 4 Computer Software
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Software History and Significance
 When the first applications of computers in business were
introduced in the early 1950s, software was less important
(and less costly) in computer systems
 Today, software comprises a much larger percentage of the
cost of modern computer systems
 The Software Crisis
 no software applications fast enough to keep up with rapidly
changing business conditions and rapidly evolving technologies
 not only must new applications be developed quickly, but existing
software must also be maintained
 increasing complexity, leads to the increased potential for “bugs”
 testing and “debugging” software is expensive and timeconsuming
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Software History and Significance
(continued …)
Software Fundamentals
 computer programs - sequences of instructions for
the computer
 programming - process of writing (or coding)
programs
 programmers - individuals who perform
programming
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Chapter 4 Computer Software
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System Software
System software
 the class of programs that control and support the
computer system and its information processing
activities
 facilitates the programming, testing, and
debugging of computer programs
 usually independent of any specific type of
application
 support application software by directing the
basic functions of the computer
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Chapter 4 Computer Software
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System Software (continued …)
System Control Program
 programs that control the use of the hardware,
software and data resources of a computer system
 operating system (main system control program)
» supervises the overall operation of the computer,
including monitoring the computer’s status and
scheduling operations, which include controlling the
input and output processes
» allocates CPU time and main memory to programs
running on the computer, and also provides an interface
between the user and the hardware
Introduction to Information Technology
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Chapter 4 Computer Software
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System Software (continued …)
System Control Program (continued …)
 Process management
» managing the program or programs running on the
processor at a given time
 Multitasking (or multiprogramming)
» managing two or more tasks, programs, running on the
computer system at the same time
 Time-sharing
» a number of users operate on-line with the same CPU, but
each uses a different input/output terminal
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Chapter 4 Computer Software
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System Software (continued …)
System Control Program (continued …)
 Multithreading
» a form of multitasking that focuses on running multiple tasks
within a single application simultaneously
 Multiprocessing
» a computer system with two or more processors that can run
more than one program or thread at a given time by assigning
them to different processors
 Virtual memory
» simulates more main memory than actually exists in the
computer system
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System Software (continued …)
System Control Program (continued …)
 File Management and Security
» managing the arrangement of, and access to, files held in
secondary storage
 Fault Tolerance
» the ability of a system to produce correct results and
continue to operate even in the presence of faults or errors
 Graphical User Interface (GUI)
» allows users to have direct control of visible objects and
actions that replace complex command syntax
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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System Software (continued …)
System Control Program (continued …)
 Major Desktop Operating Systems
MS-DOS
Windows 3.xx
Windows 98
Windows 95
Windows NT
Windows 2000
Windows CE
IBM’s OS/2
Macintosh Operating System
UNIX
Java Operating System (JavaOS)
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Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
System Software (continued …)
System Control Program (continued …)
 Major Departmental Sever Operating System
» UNIX, Windows NT Server, IBM’s OS/2 Warp Server,
Novell NetWare, and IBM’s OS/400
 Major Enterprise Operating Systems
» IBM’s MVS (Multiple Virtual Storage), IBM’s VM
(Virtual Machine), IBM’s VSE (Virtual Storage
Extended), and Digital Open VMS (Virtual machine
System)
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System Software (continued …)
System Support Programs
 System support programs
» support the operations, management, and users of a
computer system
 System utility programs
» accomplish common tasks such as sorting records,
checking the integrity of diskettes, creating
directories and subdirectories, restoring accidentally
erased files, locating files within the directory
structure, managing memory usage, and redirecting
output
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System Software (continued …)
System Support Programs (continued …)
 System performance monitors
» monitor the processing of jobs on a computer system
and produce reports containing detailed statistics
concerning the use of system resources
 System security monitors
» monitor the use of a computer system to protect it
and its resources from unauthorized use, fraud, or
destruction
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Turban, Rainer and Potter
Chapter 4 Computer Software
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Application Software
Application Software
 instructions that direct a computer system to perform
specific information processing activities and provide
functionality for users
Types of Application Software
 Proprietary application software
» addresses a specific or unique business need for a company
 Off-the-shelf application software
» developed programs sold to many organizations
» may be customizable or may be standard package
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Chapter 4 Computer Software
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Application Software (continued …)
 Personal Application Software
 one of the off-the-shelf application programs
that are not linked to any specific business
function, but instead support general types of
processing
Encompassing spreadsheet
Desktop publishing
Graphics
Data management
Publishing
Multimedia
Word processing
Communications
GroupWare
Speech recognition software
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Application Software (continued …)
Software Suites
 collections of application software packages
that integrate the functions of the packages
 examples : Microsoft Office, Novell Perfect
Office, and Lotus SmartSuite
 generally include : a spreadsheet program, word
processor, database program, and graphics
package with the ability to move document,
data. And diagrams among them
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Software Issues
Software Selection
 Selection factors
» size and location of the current and future user base
» system administration tools
» initial and subsequent costs
» current and future system capabilities
» existing computing environment
» in-house technical skills
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Software Issues (continued …)
Software Evaluation
 evaluation checklist
» ease of use in development
» maintenance
» graphic presentation
» data handling
» performance
» environments and hardware
» vendor support
» learning
» reporting capability
» general functionality
» output options
» security
» documentation
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Turban, Rainer and Potter
Chapter 4 Computer Software
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Software Issues (continued …)
Software Licensing
 copyright - exclusive legal right to reproduce,
publish, and sell the software
 licenses - permission granted under the law to
engage in an activity otherwise unlawful
Software Upgrades
 revised software may offer valuable enhancements
but may offer little in terms of additional capabilities
 revised software may contain bugs
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Software Issues (continued …)
Shareware, Freeware, and Cheapware
 Shareware - low price software
 Freeware - free copyrighted software
 Cheapware - free public-domain software
Open Systems
 a paradigm of computing products that work together
 use the same operating system with compatible
software on all the different computers in a system
 to empower designers to choose the best computer
hardware, operating system, and application software
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Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
Programming Languages
Machine Language (first generation of programming languages)
… ..
 the lowest level computer language
……
 composed of binary digits
 all other languages are translated into machine
language before the computer can run the instructions
Assembly Language (second generation of computer languages)
 a lower-level but more user-friendly language
 assembler - translates an assembly language program
into machine language
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Programming Languages
(continued …)
Procedural Languages (third generation languages)
 much closer to natural language
 use common words rather than abbreviated
mnemonics
 compiler - translates the entire program at once
 interpreter - translates and executes one source
program statement at a time
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Programming Languages
(continued …)
Nonprocedural Language (fourth generation languages)
 a high-level language
 allows the user to specify the desired result without
having to specify the detailed procedures needed for
achieving the result
 can be used by non technical users
Natural Language programming Languages (fifth
generation languages)
 translates natural languages into a structured, machinereadable from are extremely complex
Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
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Programming Languages
(continued …)
Visual Programming Languages
 used within a graphical environment
 example : Visual Basic and Visual C++
 popular to non technical users
Hypertext Markup Language (HTML)
 standard language used in World Wide Web
 contains text, images, and other types of
information such as data files, audio, video, and
executable computer programs
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Chapter 4 Computer Software
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Programming Languages
(continued …)
Virtual Reality Modeling Language (VRML)
 a file format for describing three-dimensional
interactive worlds and objects
 can be used with the World Wide Web
Object-Oriented Programming Languages (OOP)
 based on the idea of taking a small amount of data and
the instructions about what to do with that data and
putting both of these together into what is called an
object
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Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
Enterprise Software
Difficulty in Most Organizations
 the sheer complexity that arises from all the different
types of hardware and software that they use
Package Wanted by an Organization
 support integration between functional (i.e., human
resource, operations, marketing, finance, accounting,
etc.) modules
 be quickly changed or enhanced
 present a common graphical look-and-feel
 help to reduce training and operation costs
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Turban, Rainer and Potter
Chapter 4 Computer Software
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Enterprise Software (continued …)
Enterprise Software
 manages a company’s vital operations, such as
supply chain management (movement of raw
material from suppliers through shipment of
finished goods to customers), inventory
replenishment, ordering, logistics coordination,
human resource management, manufacturing,
operations, accounting, and financial
management
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Introduction to Information Technology
Turban, Rainer and Potter
Chapter 4 Computer Software
Enterprise Software (continued …)
System Anwendung Produket (SAP)
 one of the largest vendors (holds 30% of the enterprise
software market)
 strength :  high degree of integration  support for
multi-site, multi-currency operations
 R / 3 - flagship client/server product
» has a high degree of functional integration across the enterprise
» criticism : complex, time-consuming and expensive to install
and integrate with other systems
» decoupling the models of R/3 into separate components, each
with its own database