SAK3002 – IT and Its Applications Chapter 3SAK3002 – Information Technology and Its Application...

Chapter 3 SAK3002 – Information Technology and Its Application

SAK3002 – IT and Its Applications

COMPUTER SOFTWARECOMPUTER SOFTWARE

33ChapterChapter



Objectives of this chapter:Objectives of this chapter:

Identify the types of system software

Identify the types of operating system

Describe the functions of an operating system

Identify utility programs

Explain the purpose of the utilities program

You can…



OverviewOverview

This chapter covers System Software

Operating System Utility Program



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

IntroductionIntroduction



Introduction (cont’d)Introduction (cont’d)

Software Layers



System SoftwareSystem Software What is system software?

Programs that Programs that maintain operation maintain operation

of computerof computer

OperatingOperating Systems Systems Utility ProgramsUtility Programs

Two categories



3.1 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 SystemOperating System What is an operating system?



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)Operating System (cont’d)



The functions of an operating system

administer security

start the computer (Booting)

manage memory

monitor performance

control a network

provide a user interfacemanage programs

provide file management and other utilities

establish an Internet connection

schedule jobs and configure devices




Booting

Cold boot Turning on computer that has been powered off

Warm boot Restarting computer that is powered on

Process of starting or restarting a computer




A personal computer boot up process

Step 1. Power supply sends signal to com-ponents in system unit

Step 4. Results of POST are compared with data in CMOS chip

Step 2. Processor 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 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

Step 7. Operating system loads configuration information and displays desktop on screen




4 main functions of OS:Manage computer programsManage computer hardwareProvides user interfaceSupport application software




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 multi-tasking, multithreading and multiprocessing

Single tasking Runs only one program at a time




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




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




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




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




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.

With virtual memory (VM), portion of hard disk is allocated to function as RAM




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




What is a device driver?

Device Device DriverDriver

Program that Program that tells operating system tells operating system how to communicate how to communicate

with devicewith device

With With Plug and PlayPlug and Play, , operating system operating system

automatically configures automatically configures new devices as you new devices as you

install theminstall them Also called Also called driverdriver




Spooling

Sending print jobs to buffer instead of directly to printer Print jobs line up in queue




Provides User Interface 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:i. 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




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




User interface

command-line interface menu-driven interface

Controls how you enter data and instructions and how information displays on screen




Graphical User Interface (GUI)

User interacts with menus and visual images such as icons and buttons




Device-dependent

Runs only on specific type of

computer

Some characteristics of operating systems

Downward compatible

Works with application software written for earlier

version of operating system

Upward compatible

Runs on new versions of operating system

Proprietary software

Privately owned and limited to specific vendor

or computer model

Device-independent

Runs on many manufacturers’

computers



Stand-aloneStand-alone

Three categories of operating systems

EmbeddedEmbedded NetworkNetwork



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




Fast, reliable Windows operating system

Stand-Alone Operating SystemsStand-Alone Operating Systems Windows XP

Available in five editions: Home Edition, Professional Edition, Tablet PC Edition,Media Center Edition,and 64-bit Edition



Successor to Windows XP, containing a new interface and new / enhanced features

Stand-Alone Operating SystemsStand-Alone Operating Systems Windows Vista

Available in several editions, grouped into Home and Business categories



Stand-Alone Operating SystemsStand-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 SystemsStand-Alone Operating Systems

UNIX Used by power users

because of its flexibility and power

Most versions offer GUI

Available forcomputers of allsizes



Stand-Alone Operating SystemsStand-Alone Operating Systems Linux

Red Hat provides a version of Linux called Red Hat Enterprise 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



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 SystemsNetwork Operating Systems

Examples of network

operating systems

NetWareNetWare

Designed for Designed for client/server client/server

networksnetworks

Windows Windows Server 2003Server 2003

Upgrade to Windows Upgrade to Windows 2000 Server2000 Server

UNIX / LinuxUNIX / Linux

Multi-purposeMulti-purposeoperating systemoperating system

SolarisSolaris Version of UNIX Version of UNIX developed by Sun developed by Sun

MicrosystemsMicrosystems

Specifically for Specifically for e-commerce e-commerce applicationsapplications



Embedded Operating SystemsEmbedded 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 SystemsEmbedded Operating Systems Operating systems for PDAs

Windows Mobile for Pocket PC Palm OS for Palm




Embedded Linux

Scaled-down Linux operating systemdesigned for PDAs, smart phones,smart watches, set-top boxes,Internet telephones, and otherdevices




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



3.2 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.

Utility programUtility 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 ProgramOS 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




Uninstaller

In Windows XP, In Windows XP, uninstaller is in Add/Remove uninstaller is in Add/Remove

Programs in Control PanelPrograms in Control Panel

Removes a Removes a program and program and

all associated filesall associated files




Disk scanner

Detects and corrects problems on hard disk

Searches for and removes unnecessary files




Disk defragmenter

Reorganizes files and unused space on hard disk so programs run faster

fragmented disk

disk after defragmentation process




Diagnostic utility

Compiles technical information about hardware and some software

Prepares report outlining problems




Backup utility

Copies selected files or entire hard disk onto another storage medium

Most compress files during backup to require less storage space




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 ProgramsStand-Alone Utility Programs Antivirus program

Identifies and removes viruses in memory, storage media, and incoming files

Must be updated frequently



Stand-Alone Utility ProgramsStand-Alone Utility Programs What is a virus?

Potentially damaging computer program Affects computer without user’s knowledge

SIGNS OF SIGNS OF VIRUS VIRUS

INFECTIONINFECTION

• 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 ProgramsStand-Alone Utility Programs Spyware

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



Programs that remove or block certain items from being displayed

Pop-up Blockers

Stand-Alone Utility ProgramsStand-Alone Utility Programs Internet filters

Anti-SpamPrograms

WebFilters



Stand-Alone Utility ProgramsStand-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 ProgramsStand-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 ProgramsStand-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



End of Chapter 3

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