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COMPUTER SOFTWARE
GENERAL OBJECTIVES
After studying this chapter, you should be able to:
❖ Define a computer software.
❖ Correctly classify software into system and application.
❖ Compare and contrast software into system and application.
❖ Understand the qualities of a good software
❖ Define an operating system.
❖ Understand the main computer user interfaces
❖ State and explain the types of Operating System.
❖ State and explain the functions of Operating System.
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INTRODUCTION
It is the collection of computer programs and related
data that provide the instructions telling a computer
what to do.
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Characteristics
Descriptions
Portability It is the ability for software to operate on multiple platforms. For
example, will an application running in Windows run in GNU Linux.
Reliability Reliability refers to the ability for software to perform its intended
functions and operations in an environment without experiencing
failure.
Usability Usability is the measure of software’s potential to accomplish the goals
of the user.
Performance Performance tells us of how well the required features of software can
perform assigned tasks.
Availability Availability refers to the ratio of time software is functional to the total
time it is required to function. Sometimes, it is expressed in qualitative
terms, indicating the extent to which software can work.
Efficiency Efficiency refers to how fast software will carry out a given task or a
given set of tasks. It is often measured in time.
ATTRIBUTES OF SOFTWARE
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Computer Software
What is system software?
➢ Programs that control the operations of the computer
and its devices
What is application software?
Presentation
Graphics
Spreadsheet
Database
Word
Processing
➢ Programs that perform specific tasks for users
Two types are
operating systems
and utility programs
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System Software
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Computer Software
What is a programmer?
➢ Someone who develops
application or system
software
▪ Programmer writes
instructions to
direct computer to
process data into
information
Javascript program
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System Software
What is system software?
➢ Programs that control
the operations of the
computer
➢ Serves as the interface
between the user, the
application software,
and the computer’s
hardware
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System Software
What is system software?
Operating system (OS)
(sometimes called the platform)
coordinates all activities
among computer
hardware
resources
Programs that
control operation
of computer
Two types are
operating systems
and utility programs
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Computer Software
Operating System (OS)
is a set of programs
that coordinates all
activities among
computer hardware
devices and allows
users to run
application software
Utility Programs allow the user to
perform maintenance-type tasks
usually related to managing a
computer, its devices or its programs
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Operating Systems
What is a cross-platform application?
Operating System/
Platform A
Operating System/
Platform B
Operating System/
Platform C
Operating System/
Platform D
Application
➢ Runs identically on multiple operating systems
▪ Operating system that computer uses is sometimes
called the platform
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Operating Systems
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Operating Systems
What are the functions of an operating system?
monitor
performance
provide a user interface
provide file
management and
other utilities
establish an
Internet connection
control a
network
administer
security
start the computer manage programs
schedule jobs and
configure devices
manage
memory
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Popular Operating Systems
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Operating System Functions
What messages display on the screen when you boot the
computer?
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Operating System Functions
What is a user interface?
command-line interface
menu-driven interface
➢ Controls how you enter data and instructions and how
information displays on screen
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Operating System Functions
What is a graphical user
interface (GUI)?
➢ User interacts with
menus and visual
images such as icons
and buttons
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▪ Foreground contains
program you are using
▪ Background contains
programs that are
running but are not
in use
Operating System Functions
What is single user/
multitasking?
➢ Working on two or
more programs that
reside in memory at
same time
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Has duplicate
components such as
processors, memory,
and disk drives
Enables two or
more users to
run programs
simultaneously
Continues to
operate when one
of its components
fails
Operating System Functions
What are other program management features of
operating systems?
Can support two
or more processors
running programs
at same time
fault-tolerant computer
multiuser
multiprocessing
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Operating System Functions
What is memory management?
Step 1. The
operating system
transfers the least
recently used data
and program
instructions to disk
because memory is
needed for other
functions.
Step 2. The
operating system
transfers data and
program instructions
from disk to
memory when they
are needed.
➢ Optimizing use of random access memory (RAM)
➢ With virtual memory (VM), portion of hard disk is
allocated to function as RAM
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Operating System Functions
How does an operating system schedule jobs?
Transferring items
between storage
and memory
Sending
information
to output device
Processing
instructions
Receiving data
from input device
Adjusts schedule
based on
job’s priority
A job is operation
the processor manages
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Operating System Functions
What is spooling?
➢ Sending print jobs to buffer instead of
directly to printer
➢ Print jobs line up in queue
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Operating System Functions
What is a device driver?
Device
Driver
Program that
tells operating system
how to communicate
with device
With Plug and Play,
operating system
automatically configures
new devices as you
install them
Also called driver
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Operating System Functions
How do you install a device driver?
Step 1. Open Control
Panel window. Point to
Printers and Other
Hardware link.
Step 2. Click Printers and
Other Hardware link. Point
to Add a printer link.
Step 3. Click Add a
printer link. Follow
on-screen instructions.
Step 4. Add Printer
Wizard searches for
Plug and Play printers
on your computer. If it
finds any such printers,
it installs them.
Step 5. If Add Printer Wizard cannot find any Plug and
Play printers, you can select type of printer you want to
install. An on-screen prompt may ask you to insert floppy
disk, CD-ROM or DVD-ROM that contains necessary
driver files to complete the installation of printer.
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Operating System Functions
How do you establish an Internet connection?
➢ Windows XP includes New Connection Wizard
▪ Guides user through setting up connection between
computer and Internet
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Operating System Functions
How does an operating system monitor performance?
➢ Provides program, called performance monitor,
that assesses and reports information about
system resources
and devices
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Operating System Utility Programs
What is a utility program?
➢ System software that performs
maintenance-type tasks
▪ Also called
utility
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Operating System Utility Programs
What is a file manager?
➢ Performs functions such as copying, renaming,
deleting, and moving files
➢ Image viewer
displays contents
of graphics file
when you double
click on it
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Operating System Utility Programs
What is an uninstaller?
In Windows XP,
uninstaller is in Add/Remove
Programs in Control Panel
Removes a
program and
all associated files
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Operating System Utility Programs
What is a disk scanner?
➢ Detects and corrects problems on
hard disk or floppy disk
➢ Searches for and removes
unnecessary files
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Operating System Utility Programs
What is a disk defragmenter?
file before defragmenting
fragmented disk
file after
defragmenting
➢ Reorganizes files and unused space on hard
disk so programs run faster
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Operating System Utility Programs
What is a diagnostic utility?
➢ Compiles technical information
about hardware and some
software
➢ Prepares report outlining
problems
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Operating System Utility Programs
What is a backup utility?
➢ Copies selected files or entire hard disk onto
another disk or tape
➢ Most compress files
during backup to
require less storage
space
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Operating System Utility Programs
What is a screen saver?
➢ Causes monitor’s screen to display moving
image or blank screen if there is no activity
for a specified time
➢ To secure computer,
user configures screen
saver to require
password to
deactivate
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Device-
dependent
Runs only on specific
type of computer
Types of Operating Systems
What are some characteristics of operating systems?
Downward
compatible
Works with application
software written for
earlier version of
operating system
Upward
compatible
Works with application
software written for new
versions of operating
system
Proprietary
software
Privately owned and
limited to specific vendor
or computer model
Device-
independent
Runs on many
manufacturers’
computers
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Stand-alone
Types of Operating Systems
What are three categories of operating systems?
Embedded Network
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Stand-Alone Operating Systems
What is DOS (Disk Operating System)?
D
Developed in
early 1980s
for personal
computers
O
Used command-line
interface when first
developed, later
included menus
S
Hardly used today
because it does
not offer GUI
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Stand-Alone Operating Systems
How do Windows versions compare?
Windows Version Year Released
Windows 3.x 1990
Windows NT 3.1 1993
Windows 95 1995
Windows NT Workstation 4.0 1996
Windows 98 1998
Windows Millennium Edition 2000
Windows 2000 Professional 2000
Windows XP 2001
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➢ Microsoft’s fastest, most reliable Windows
operating system
Stand-Alone Operating Systems
What is Windows XP?
➢ Available in five
editions:
Home Edition,
Professional Edition,
Tablet PC Edition,
Media Center Edition,
and 64-bit Edition
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Windows XP Features
Appearance and Performance
Administration
Help and Support
Communications and the Web
Digital Media
Stand-Alone Operating Systems
What are some features of Windows XP?
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Stand-Alone Operating Systems
What is Mac OS X?
➢ Available only for computers manufactured
by Apple
➢ Macintosh operating
system has been
model for most GUIs
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Stand-Alone Operating Systems
What is UNIX?
➢ Used by power users because of its flexibility
and power
➢ Most versions
offer GUI
➢ Both a stand-alone
and a network
operating system
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Stand-Alone Operating Systems
What is Linux?
Red Hat provides a version of Linux called Red Hat
Linux. The GNOME graphical user interface is shown
in this example.
➢ Popular, free, multitasking UNIX-type
operating system
➢ Open-source softwaree—
code is available to
public
➢ Both a stand-alone
and a network
operating system
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Network Operating Systems
NetWare
Designed for
client/server
networks
Windows
Server 2003
Upgrade to Windows
2000 Server
Linux
Multi-purpose
operating system
Solaris
▪ Version of UNIX
developed by Sun
Microsystems
▪ Specifically for
e-commerce
applications
What is a network operating system?
➢ Allows users to share printer,
Internet access, files, and
programs on a network
➢ Administers security
by establishing user
name and password
for each user
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Embedded Operating Systems
What is an embedded operating system?
➢ Found on most mobile
computers, PDAs, and other
small devices
➢ Windows CE .NET is
scaled-down version of
Windows
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Embedded Operating Systems
What are two operating systems for PDAs?
➢ Windows Mobile 2003 for Pocket PC
➢ Palm OS for Palm, Visor, and CLIE
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Embedded Operating Systems
What is Symbian OS?
➢ Open-source, multitasking operating system
designed for smart phones
➢ Make telephone calls,
save appointments,
browse Web, send
and receive e-mail
and faxes, and more
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Stand-Alone Utility Programs
What is a virus?
SIGNS OF VIRUS
INFECTION
➢ Potentially damaging computer program
➢ Affects computer without user’s knowledge
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Stand-Alone Utility Programs
What is an antivirus program?
➢ Identifies and removes viruses in memory, storage
media, and incoming files
➢ Must be updated frequently
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Stand-Alone Utility Programs
What is a personal firewall?
➢ Protects personal computer from unauthorized
intrusions
➢ Monitors all
transmissions
to and from
computer
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Stand-Alone Utility Programs
What is a file compression utility?
➢ Shrinks size of files to free up room
and improve performance
➢ Compressed files are sometimes called
zipped files
➢ Two popular utilities:
PKZIP and WinZip
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Stand-Alone Utility Programs
What is a personal computer maintenance utility?
➢ Identifies and fixes operating system problems and
disk problems
➢ Some continuously
monitor computer to
identify problems
before they occur
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APPLICATION SOFTWARE
Application software direct the computer to
perform one or more specific tasks for the end
user. They are designed to do the jobs that the user
wants such as word processing, spreadsheets,
database, and graphics.
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APPLICATION SOFTWARE CONT…
Application software include a variety of
programs that can be divided into three
categories:
❖ general-purpose applications
❖ special purpose applications
❖ tailor-made (bespoke) applications.
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APPLICATION SOFTWARE CONT…
GENERAL PURPOSE APPLICATION SOFTWARE
General purpose application software or
generic software is software designed to
solve a wide range of related tasks.
They are always available off-the-shelf ie.
That is, they can be bought from the market.
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GENERAL PURPOSE APPLICATION SOFTWARE EXAMPLES
TYPES OF PROCESSING EXAMPLES
Database Software Organize and access large amounts of
data.
MS-Access, Oracle,
Dbase, FileMaker
Spreadsheet Software work with numbers, calcalations and
graphs.
MS Excel, Lotus 1-2-3,
Quattro Pro, Apple
Numbers
Word Processing
Software
Create mainly text (Letters, term
papers)
MS Word, WordPerfect,
WordPad, NotePad
Presentation
Software
Build a slide presentation MS PowerPoint,
HyperStudio, Digital
Chisel
Desktop Publishing
Software
generate layouts and produce quality
text and images comparable to
traditional printing
MS Publisher, Adobe
PageMaker, Quark
Express
Graphics
Software
Work with photos and arts. Corel Draw, Adobe
Photoshop
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APPLICATION SOFTWARE CONT…
Special purpose Applications
Special purpose applications are software designed or
written for a particular situation or specific task.
They are generally not available in shops unlike generic
software and they often have to be purchased directly
from the software manufacturer or a specialist firm.
Special purpose Applications Examples
❖ Traffic control
❖ Payroll and time keeping
❖ Aircraft navigation
❖ Weather forecasting
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APPLICATION SOFTWARE CONT…
Bespoke (tailor-made) applications
Bespoke application software is software
written specifically for the needs of a user or
company. It is "tailored" to their exact
requirements.
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