Transcript What is an operating system?

Chapter
3
COMPUTER
SOFTWARE
Objectives of this chapter:
You can…
Identify the types of system software
Describe the functions of an operating system
Identify the types of operating system
Identify utility programs
Explain how to work with application software
Overview
•
This chapter covers
– System Software
•
•
Operating System
Utility Program
– Application Software
3.1 Introduction
Introduction
•
Computer software is:
–
–
–
A group of programs that connects user with
computer devices
Comprised of a sequence of instructions
Designed to instruct the computer to execute desired
functions by the users
Introduction (cont’d)
Software Layers
3.2 System Software
System Software
•
What is system software?
Programs that
maintain operation
of computer
•
Two categories
Operating Systems
Utility Programs
Operating System
•
What is an operating system?
– A group of programs that organize and manage the
whole computer operations
– OS is a set of instructions that coordinate all the
internal activities among computer hardware,
application programs and users
Operating System (cont’d)
• OS is controlled by the kernel.
• What is a kernel?
– Kernel is the supervisor program that manage the
memory and devices
– Kernel is loaded into the memory from the hard disk
(or other storage) during booting until computer is
turned off
– It is known as memory resident (because it resides in
memory as long as the power is on. Non-resident are
other programs that resides in hard disk at the same
time)
Operating System (cont’d)
•
The functions of an operating system
start the computer
(Booting)
manage programs
provide a user interface
administer
security
manage
memory
control a
network
provide file
management and other
utilities
monitor
performance
establish an
Internet connection
schedule jobs and
configure devices
Operating System (cont’d)
• Booting

Process of starting or restarting a computer


Cold boot
Turning on
computer that has
been powered off
Warm boot
Restarting
computer that is
powered on
Operating System (cont’d)
•
A personal computer boot up process
Step 1. Power supply
Step 4. Results of POST are
sends signal to components in system unit
compared with data in CMOS chip
Step 2. Processor
on a USB drive, in floppy disk drive
or CD/DVD drive, and then hard
disk
Step 6. Kernel (core) of operating
system loads into RAM
accesses BIOS to start
computer
Step 3. BIOS runs tests,
called the POST, to
check components such
as mouse, keyboard,
and adapter cards
Step 5. BIOS looks for system files
Step 7. Operating system loads
configuration information and
displays desktop on screen
Operating System (cont’d)
• 4 main functions of OS:
– Manage computer programs
– Manage computer hardware
– Provides user interface
– Support application software
Operating System (cont’d)
• Manage computer programs
– Managing programs refers to how many users,
and how many programs, an operating system
can support at one time
– An OS can be single tasking, multi-tasking,
cooperative multi-tasking, preemptive multitasking, multithreading and multiprocessing
– Single tasking
• Runs only one program at a time
Operating System (cont’d)
– Multi-tasking
• Same concept as multiprogramming
• Allows 2 or more programs at the same time
• Divide the programs into active and inactive. Active
application is called foreground application and
inactive application is background application
• CPU does not run the programs simultaneously but
manage the resources i.e. memory based on
active/inactive applications
Operating System (cont’d)
– Cooperative Multi-tasking
• Based on multi-tasking concept, whereby
foreground application controls CPU until program
ends
• But if program crashes/hang, OS needs to be
rebooted
– Preemptive Multi-tasking
• Based on multi-tasking concept
• But if program crashes/hang, OS is able to take
over CPU so other programs can be maintained
Operating System (cont’d)
– Multithreading
• One program may execute more than one task
• Example print and edit at the same time
– Multiprocessing
• Use of 2 or more processor at the same time
• Programs run simultaneously
• Each processor manage own resources
• Hardware dependant esp. motherboard
Operating System (cont’d)
• Manage computer hardware
– Memory Unit
• OS partitions the memory for each program.
• If memory is insufficient, OS may use virtual
memory, which allocates a portion of a storage
medium to function as additional RAM
• In virtual memory, programs/instructions are
stored in fixed-sized unit called pages
• If memory if full, OS will copy pages into swap file
in hard disk and reloaded into memory when
needed
Operating System (cont’d)

With virtual memory (VM), portion of hard disk is
allocated to function as RAM
Step 1. The
operating system
transfers the least
recently used data
and program
instructions to disk
because RAM is
needed for other
functions.
Step 2. The
operating system
transfers data and
program instructions
from hard disk to
RAM when they are
needed.
Operating System (cont’d)
– Input/Output Devices
• OS provides interrupt handler, a mini program to
handle interrupt from input/output devices.
• Examples of interrupt are mouse
click/scroll/keyboard punch
• OS requires device driver to operates hardware
devices. Drivers are loaded during booting
Operating System (cont’d)
•
What is a device driver?
Program that
tells operating system
how to communicate
with device
Also called driver
Device
Driver
With Plug and Play,
operating system
automatically configures
new devices as you
install them
Operating System (cont’d)
•
Spooling


Sending print jobs to buffer instead of directly to printer
Print jobs line up in queue
Operating System (cont’d)
•
Provides User Interface
•
•
•
i.
OS manages communication between the
computers and users
Users may login, run application programs,
manage files (copy/save) and on/off computers
using any type of interface
There are 3 types of command instructions:
Command line
–
–
Instructions to be typed in i.e. to save a file into diskette
is C:\WINDOWS>copy C:myfile.doc a:
Users have to memorize instructions
Operating System (cont’d)
ii. Menu-driven
–
–
User selects instruction from a text-based pull-down
menu
Instructions are entered either via mouse click/
keyboard <ENTER> of arrow keys
iii. Graphical user interface (GUI)
–
User selects instruction by mouse click or keyboard
<ENTER> icons
Operating System (cont’d)
•
User interface

Controls how you enter data and instructions and how information
displays on screen
command-line interface
menu-driven interface
Operating System (cont’d)
• Graphical User Interface (GUI)

User interacts with
menus and visual
images such as icons
and buttons
Operating System (cont’d)
•
Some characteristics of operating systems
Devicedependent
Runs only on
specific type of
computer
Proprietary
software
Privately owned and
limited to specific vendor
or computer model
Downward
compatible
Works with application
software written for
earlier version of
operating system
Deviceindependent
Runs on many
manufacturers’
computers
Upward
compatible
Runs on new versions
of operating system
Operating System (cont’d)
•
Three categories of operating systems
Embedded
Network
Stand-alone
Operating System (cont’d)
•
Stand-alone
operating
systems
–
Example: Windows
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
Windows XP SP2
2004
Windows Vista
2006
Stand-Alone Operating Systems
• Windows XP


Fast, reliable Windows
operating system
Available in five editions:
Home Edition, Professional
Edition,
Tablet PC Edition,
Media Center Edition,
and 64-bit Edition
Stand-Alone Operating Systems
• Windows Vista

Successor to Windows XP,
containing a new interface
and new / enhanced features

Available in several editions,
grouped into Home and
Business categories
Stand-Alone Operating Systems
• Mac OS X

Available only for
computers manufactured
by Apple

Macintosh operating
system has been
model for most GUIs
Stand-Alone Operating Systems
• UNIX

Used by power users
because of its flexibility
and power

Most versions
offer GUI

Available for
computers of all
sizes
Stand-Alone Operating Systems
• Linux

Popular, free, multitasking
UNIX-type operating system

Open-source software—
code is available to
public

Both a stand-alone
and a network
operating system
Red Hat provides a version of Linux called Red Hat
Enterprise Linux.
Operating System (cont’d)
•
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
Network Operating Systems
• Examples of network
operating systems
NetWare
Designed for
client/server
networks
Windows
Server 2003
UNIX / Linux
Upgrade to Windows
2000 Server
Multi-purpose
operating system
Solaris
 Version of UNIX
developed by Sun
Microsystems
 Specifically for
e-commerce
applications
Embedded Operating Systems
• Embedded operating system


Found on most mobile computers,
PDAs, and other small devices
Windows CE is
scaled-down version of Windows
Embedded Operating Systems
•
Operating systems for PDAs


Windows Mobile for Pocket PC
Palm OS for Palm
Embedded Operating Systems
•

Embedded Linux
Scaled-down Linux operating system
designed for PDAs, smart phones,
smart watches, set-top boxes,
Internet telephones, and other
devices
Embedded Operating Systems
•
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
Utility program
• A small program that provides an addition to the
capabilities provided by the operating system
• Performs maintenance-type tasks, usually related
to managing a computer, its devices, or its
programs.
OS Utility Program
•
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
OS Utility Program
•
Personal firewall

Detects and protects a
personal computer from
unauthorized intrusions

The latest update to
Windows XP
automatically enables
the built-in personal
firewall upon
installation
OS Utility Program
•
Uninstaller
Removes a
program and
In Windows XP,
uninstaller is in Add/Remove
all associated files
Programs in Control Panel
OS Utility Program
•


Disk scanner
Detects and corrects
problems on hard disk
Searches for and removes
unnecessary files
OS Utility Program
•

fragmented disk
Disk defragmenter
Reorganizes files and
unused space on hard
disk so programs run
faster
disk after
defragmentation
process
OS Utility Program
•


Diagnostic utility
Compiles technical information about
hardware and some software
Prepares report outlining problems
OS Utility Program
•
Backup utility

Copies selected files or
entire hard disk onto
another storage medium

Most compress files
during backup to require
less storage space
OS Utility Program
•
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
Stand-Alone Utility Programs
•
Antivirus program

Identifies and removes viruses
in memory, storage media, and
incoming files

Must be updated frequently
Stand-Alone Utility Programs
•
What is a virus?


Potentially damaging computer program
Affects computer without user’s knowledge
SIGNS OF
VIRUS
INFECTION
• An unusual message or image is displayed on the
computer screen
• An unusual sound or music plays randomly
• The available memory is less than what should be
available
• A program or file suddenly is missing
• An unknown program or file mysteriously appears
• The size of a file changes without explanation
• A file becomes corrupted
• A program or file does not work properly
• System properties change
Stand-Alone Utility Programs
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Spyware

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
Program placed on a computer without the user’s knowledge that
secretly collects information about the user
Often enters a computer as a result of a user installing a new program
A spyware remover is a program that detects and deletes spyware
Stand-Alone Utility Programs
•
Internet filters

Programs that remove or block certain items from
being displayed
Anti-Spam
Programs
Web
Filters
Pop-up
Blockers
Stand-Alone Utility Programs
•
File compression utility



Shrinks size of files to free up room and improve
performance
Compressed files are sometimes called zipped
files
Two popular utilities:
Winrar and WinZip
Stand-Alone Utility Programs
•
CD/DVD burning software

Writes text, graphics, audio,
and video files to a recordable
or rewriteable CD or DVD
Stand-Alone Utility Programs
•
Personal computer maintenance utility


Identifies and fixes operating
system problems and disk
problems
Some continuously
monitor computer to
identify problems
before they occur
3.3 Application Software
Introduction
•
What is application software?
Programs designed to make users more productive and/or assist
them with personal tasks
Introduction (cont’d)
Introduction (cont’d)
•
How is software distributed?
–
–
–
–
–
–
–
Packaged software, mass-produced
Custom software, performs functions specific to a business or
industry
Open source software, provided for use, modification, and
redistribution
Shareware, copyrighted software that is distributed free for trial
period
Freeware, copyrighted software provided at no cost
Public-domain software, freeware with no copyright restrictions
Pirated Software, software obtained illegally
Introduction (cont’d)
•
Common Features of Software
–
–
•
User interface - the user-controllable display screen that allows you to
communicate, or interact, with the computer
A User can interact with the display screen using a keyboard or a
mouse
The GUI
–
–
Graphical user interface (GUI) - allows users to use a mouse or
keyboard strokes to select icons and commands from menus
The three features of GUI are desktop, icons, and menus
Introduction (cont’d)
–

Window
A rectangular area of the screen that displays a program, data, and/or
information
Menu Bar
Introduction (cont’d)
–

Dialog box
A window that provides information, presents available options, or requests
a response
Introduction (cont’d)
•
The Help Command
–
Help command - a
command generating
a table of contents,
an index, and a
search feature that
can help you locate
answers
Introduction (cont’d)
•
Software Suite
–
Individual applications share a common program code
–
Popular office suites offer a word processor, spreadsheet, database, presentation,
and other programs
Microsoft Office
WordPerfect
Office 12
Lotus
SmartSuite
Word processing
Microsoft Word
WordPerfect
Word Pro
Spreadsheet
Microsoft Excel
Quattro Pro
Lotus 1-2-3
Database
Microsoft Access
Paradox
Lotus Approach
Presentation
Graphics
Microsoft PowerPoint
Corel
Presentations
Freelance
Graphics
Personal information
managers
Microsoft Outlook
Corel Central
Lotus Organizer
Word Processing
•
What is word processing software?

Allows users to create and
manipulate text and graphics

This process includes editing, deleting
and printing the text and multimedia resources

Clip art is a collection
of graphics
that you can
insert in
documents
Word Processing (cont’d)
• Popular word processing features
AutoCorrect
Columns
AutoFormat
Grammar
Checker
Tracking
Changes
Ink Input
Reading
Layout
Mail Merge
Smart Tags
Collaboration
Tables
Macros
Research
Templates
Voice
Recognition
Thesaurus
Web Page
Development
Spreadsheet software
•
What is spreadsheet software?
–
–
Organizes data in rows and columns
Performs calculations and
recalculates when data changes
= A1+B2 (*C12)
= D1+E2 (*F12)
= SUM (C12:Y12)
Spreadsheet software (cont’d)
• How is spreadsheet organized?



Columns identified by letters
Rows identified by numbers
A cell is the intersection of a column
and row
Spreadsheet
•
Function

A predefined formula
that performs
common calculations
=B10+B11+B12+B13+B14
=SUM(B10:B14)
Spreadsheet software (cont’d)
•
Charting

Allows you to display
spreadsheet data in
graphical form
Spreadsheet software (cont’d)
•
There are 4 types of charts:
i.
Column Chart
•
Used to show changes in time and widely known as the
time series
ii. Bar Chart
•
Not suitable for time-based data. Best used for
comparison purposes
iii. Line Chart
•
Suitable for time series data
iv. Pie Chart
•
Widely used to show percentages
Presentation software
•
Presentation graphics software



Used to create visual aids for presentations
A presentation is sometimes
called a slide show
Example: Microsoft PowerPoint
Presentation software (cont’d)
–
Presentation-graphics programs offer templates to
help organize presentations
– Templates are of two types:
• Design templates - offer formats, layouts, background
patterns, and color schemes that can apply to general
forms of content material
• Content templates - offer formats for specific subjects
Presentation software (cont’d)
–
Graphical presentation program allow users to view
the presentation in variety of forms:
i.
Slide view
–
ii.
View the slides one by one – users may add or edit slide
Outline view
–
Display all text only
iii. Slide sorter view
–
Display graphical images of each slides and allow users to change the
position of the slides
iv. Notes view
–
v.
Allow speaker notes to be added at each slide
Master
–
All presentation software must have the basic components of the slide
4.5 Database Software
Database Software
•
Database software
Allows you to create
and manage data
Add, change, delete,
sort, and retrieve data
Database Software (cont’d)
–
–
–
Essential to manage a large amount of data, for
easy, direct access, to avoid data redundancy and
to save time. Examples are: Lotus Notes, Dbase,
Microsoft Access and Paradox
Database - a collection of interrelated files
Database software - a program that sets up and
controls the structure of a database and access to
the data
Database Software (cont’d)
•
Types of database software:
i.
Dekstop Database
•
•
•
•
•
ii.
For individual use
Usage is limited to 5 to 10 users at a time
The database functionality is limited as compare to a network databse
The data security system is limited especially in locking the database
Examples of databases are Microsoft Access, and Microsoft Visual FoxPro
Network Database
•
•
•
•
•
•
For both individual and corporate use
Support bigger number of users that is exceeding 100 users depending on
the database brand
Moreo funtionalities provided
Information access and retrieval is faster
Higher security system
Examples are Oracle, Microsoft SQL Server, and Dbase
Database Software (cont’d)
•
Benefits of databases:
i.
ii.
iii.
iv.
v.
Avoid data redundancy
Data integration
Data security
Data independence
Data maintenance
Database Software (cont’d)
•
The parts of a database



A table contains records
A record is a row in a
table that contains
information about a
given person, product,
object, or event
A field is a column in
a table that contains
a specific category of
data within a record
Database Software (cont’d)
•
How a relational database is organized:
– Tables of rows and columns
– Row (record) - example: a person’s address
–
Column (field) - example: the person’s last name
Database Software (cont’d)
•
How various records can be linked:
– Key field - a field that is used to sort data
– Primary key - holds a unique value for each record
– Foreign key - used to cross-reference data among
relational tables
Graphics and Multimedia Software
•
What is graphics and Multimedia Software?
–
Software that used to manipulate images, audio and
video.
Graphics and Multimedia
Software
•
Paint/image editing software



Used to create and
modify graphical
images
Sometimes called
illustration
software
Example:


Microsoft Paint
Corel’s Paint Shop Pro
Graphics and Multimedia
Software
•
Professional photo editing software



Allows users to customize digital photographs
Save images in a variety of file formats
Example: Adobe Photoshop, Adobe Ilustrator
Graphics and Multimedia
Software
•
Video and audio editing software



Video editing software allows you to modify a segment of a video, called a
clip
Audio editing software allows you to modify audio clips
Example: Adobe Premier, Cakewalk Sonar, Cubase etc
Graphics and Multimedia
Software
•
Multimedia authoring software


Allows you to combine
text, graphics, audio,
video, and animation
in an interactive
application
Example

Macromedia Flash

Macromedia Director
Other Software (cont’d)
•
Note taking software

Enables users to enter typed text,
handwritten comments, drawings,
or sketches anywhere on the page

Notes are organized like a
notebook
Other Software (cont’d)
•
Project management software

Allows you to plan, schedule,
track, and analyze the events,
resources, and costs of a
project
Other Software (cont’d)
•
Accounting software

Helps companies record and
report their financial
transactions
Other Software (cont’d)

Web page authoring software

Helps users of all skill levels to create Web pages

Some application software programs include Web page
authoring programs
video
audio
graphical
images
animation
organize
manage
maintain
Web pages
and/or
Web sites
End of Chapter 3