1. 3 COMPUTER SOFTWARE Chapter
Chapter 3 SAK3002 – Information Technology and Its Application

2. 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 the purpose of the utilities program
Chapter 3 SAK3002 – Information Technology and Its Application

3. Overview This chapter covers System Software Operating System
Utility Program
GO!
Chapter 3 SAK3002 – Information Technology and Its Application

4. 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
Chapter 3 SAK3002 – Information Technology and Its Application

5. Introduction (cont’d)
Software Layers
Chapter 3 SAK3002 – Information Technology and Its Application

6. Programs that maintain operation of computer
System Software
What is system software?
Programs that maintain operation of computer
Two categories
Operating Systems
Utility Programs
Chapter 3 SAK3002 – Information Technology and Its Application

7. 3.1 Operating System
Chapter 3 SAK3002 – Information Technology and Its Application

8. 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
Chapter 3 SAK3002 – Information Technology and Its Application

9. 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)
Chapter 3 SAK3002 – Information Technology and Its Application

10. 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
establish an Internet connection
monitor performance
schedule jobs and configure devices
provide file management and other utilities
Chapter 3 SAK3002 – Information Technology and Its Application

11. 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
Chapter 3 SAK3002 – Information Technology and Its Application

12. Operating System (cont’d)
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 5. BIOS looks for system files on a USB drive, in floppy disk drive or CD/DVD drive, and then hard disk
Step 2. Processor accesses BIOS to start computer
Step 6. Kernel (core) of operating system loads into RAM
Step 3. BIOS runs tests, called the POST, to check components such as mouse, keyboard, and adapter cards
Step 7. Operating system loads configuration information and displays desktop on screen
Chapter 3 SAK3002 – Information Technology and Its Application

13. Operating System (cont’d)
4 main functions of OS:
Manage computer programs
Manage computer hardware
Provides user interface
Support application software
Chapter 3 SAK3002 – Information Technology and Its Application

14. 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 multi-tasking, multithreading and multiprocessing
Single tasking
Runs only one program at a time
Chapter 3 SAK3002 – Information Technology and Its Application

15. 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
Chapter 3 SAK3002 – Information Technology and Its Application

16. 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
Chapter 3 SAK3002 – Information Technology and Its Application

17. 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
Chapter 3 SAK3002 – Information Technology and Its Application

18. 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
Chapter 3 SAK3002 – Information Technology and Its Application

19. 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.
Chapter 3 SAK3002 – Information Technology and Its Application

20. 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
Chapter 3 SAK3002 – Information Technology and Its Application

21. Operating System (cont’d)
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
Chapter 3 SAK3002 – Information Technology and Its Application

22. Operating System (cont’d)
Spooling
Sending print jobs to buffer instead of directly to printer
Print jobs line up in queue
Chapter 3 SAK3002 – Information Technology and Its Application

23. Operating System (cont’d)
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:
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
Chapter 3 SAK3002 – Information Technology and Its Application

24. Operating System (cont’d)
Menu-driven
User selects instruction from a text-based pull-down menu
Instructions are entered either via mouse click/ keyboard <ENTER> of arrow keys
Graphical user interface (GUI)
User selects instruction by mouse click or keyboard <ENTER> icons
Chapter 3 SAK3002 – Information Technology and Its Application

25. 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
Chapter 3 SAK3002 – Information Technology and Its Application

26. Operating System (cont’d)
Graphical User Interface (GUI)
User interacts with menus and visual images such as icons and buttons
Chapter 3 SAK3002 – Information Technology and Its Application

27. Some characteristics of operating systems
Proprietary software
Privately owned and limited to specific vendor or computer model
Device-dependent
Runs only on specific type of computer
Device-independent
Runs on many manufacturers’ computers
Downward compatible
Works with application software written for earlier version of operating system
Upward compatible
Runs on new versions of operating system
Chapter 3 SAK3002 – Information Technology and Its Application

28. Three categories of operating systems
Embedded
Network
Stand-alone
Chapter 3 SAK3002 – Information Technology and Its Application

29. Operating System (cont’d)
Windows Version Year Released
Windows 3.x 1990
Windows NT
Windows
Windows NT Workstation
Windows
Windows Millennium Edition 2000
Windows 2000 Professional 2000
Windows XP 2001
Windows XP SP2 2004
Windows Vista 2006
Stand-alone operating systems
Example: Windows
Chapter 3 SAK3002 – Information Technology and Its Application

30. 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
Chapter 3 SAK3002 – Information Technology and Its Application

31. 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
Chapter 3 SAK3002 – Information Technology and Its Application

32. Stand-Alone Operating Systems
Mac OS X
Available only for computers manufactured by Apple
Macintosh operating system has been model for most GUIs
Chapter 3 SAK3002 – Information Technology and Its Application

33. 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
Chapter 3 SAK3002 – Information Technology and Its Application

34. 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.
Chapter 3 SAK3002 – Information Technology and Its Application

35. 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
Chapter 3 SAK3002 – Information Technology and Its Application

36. Network Operating Systems
NetWare
Designed for client/server networks
Examples of network
operating systems
Windows Server 2003
Upgrade to Windows 2000 Server
UNIX / Linux
Multi-purpose operating system
Solaris
Version of UNIX developed by Sun Microsystems
Specifically for e-commerce applications
Chapter 3 SAK3002 – Information Technology and Its Application

37. Embedded Operating Systems
Found on most mobile computers, PDAs, and other small devices
Windows CE is scaled-down version of Windows
Chapter 3 SAK3002 – Information Technology and Its Application

38. Embedded Operating Systems
Operating systems for PDAs
Windows Mobile for Pocket PC
Palm OS for Palm
Chapter 3 SAK3002 – Information Technology and Its Application

39. 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
Chapter 3 SAK3002 – Information Technology and Its Application

40. Embedded Operating Systems
Symbian OS
Open-source, multitasking operating system designed for smart phones
Make telephone calls, save appointments, browse Web, send and receive and faxes, and more
Chapter 3 SAK3002 – Information Technology and Its Application

41. 3.2 Utility Program
Chapter 3 SAK3002 – Information Technology and Its Application

42. 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.
Chapter 3 SAK3002 – Information Technology and Its Application

43. 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
Chapter 3 SAK3002 – Information Technology and Its Application

44. 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
Chapter 3 SAK3002 – Information Technology and Its Application

45. OS Utility Program Uninstaller
Removes a program and all associated files
In Windows XP, uninstaller is in Add/Remove Programs in Control Panel
Chapter 3 SAK3002 – Information Technology and Its Application

46. OS Utility Program Disk scanner
Detects and corrects problems on hard disk
Searches for and removes unnecessary files
Chapter 3 SAK3002 – Information Technology and Its Application

47. OS Utility Program Disk defragmenter
fragmented disk
disk after defragmentation process
Disk defragmenter
Reorganizes files and unused space on hard disk so programs run faster
Chapter 3 SAK3002 – Information Technology and Its Application

48. OS Utility Program Diagnostic utility
Compiles technical information about hardware and some software
Prepares report outlining problems
Chapter 3 SAK3002 – Information Technology and Its Application

49. 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
Chapter 3 SAK3002 – Information Technology and Its Application

50. 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
Chapter 3 SAK3002 – Information Technology and Its Application

51. Stand-Alone Utility Programs
Antivirus program
Identifies and removes viruses in memory, storage media, and incoming files
Must be updated frequently
Chapter 3 SAK3002 – Information Technology and Its Application

52. Stand-Alone Utility Programs
What is a virus?
Potentially damaging computer program
Affects computer without user’s knowledge
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
SIGNS OF VIRUS INFECTION
Chapter 3 SAK3002 – Information Technology and Its Application

53. Stand-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
Chapter 3 SAK3002 – Information Technology and Its Application

54. Stand-Alone Utility Programs
Internet filters
Programs that remove or block certain items from being displayed
Anti-Spam
Programs
Web Filters
Pop-up Blockers
Chapter 3 SAK3002 – Information Technology and Its Application

55. 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
Chapter 3 SAK3002 – Information Technology and Its Application

56. Stand-Alone Utility Programs
CD/DVD burning software
Writes text, graphics, audio, and video files to a recordable or rewriteable CD or DVD
Chapter 3 SAK3002 – Information Technology and Its Application

57. 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
Chapter 3 SAK3002 – Information Technology and Its Application

58. End of Chapter 3
Chapter 3 SAK3002 – Information Technology and Its Application