COMPUTER SOFTWARE

1. 3 Chapter COMPUTER SOFTWARE

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

3. Overview • This chapter covers • System Software • Operating System • Utility Program GO!

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

5. Introduction (cont’d) Software Layers

6. System Software • What is system software? Programs that maintain operation of computer • Two categories Utility Programs Operating Systems

7. 3.1 Operating System

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

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)

10. start the computer (Booting) administer security control a network establish an Internet connection schedule jobs and configure devices monitor performance Operating System (cont’d) • The functions of an operating system manage programs provide a user interface manage memory provide file management and other utilities

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

12. Operating System (cont’d) • A personal computer boot up process Step 4.Results of POST are compared with data in CMOS chip Step 1.Power supply sends signal to com-ponents in system unit 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

13. Operating System (cont’d) • 4 main functions of OS: • Manage computer programs • Manage computer hardware • Provides user interface • Support application software

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

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

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

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

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

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.

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

21. With Plug and Play, operating system automatically configures new devices as you install them Program that tells operating system how to communicate with device Device Driver Operating System (cont’d) • What is a device driver? Also called driver

22. Operating System (cont’d) • Spooling • Sending print jobs to buffer instead of directly to printer • Print jobs line up in queue

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

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

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

26. Operating System (cont’d) • Graphical User Interface (GUI) • User interacts with menus and visual images such as icons and buttons

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

28. Network Embedded Stand-alone • Three categories of operating systems

29. 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 Operating System (cont’d) • Example: Windows • Stand-alone operating systems

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

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

32. Stand-Alone Operating Systems • Mac OS X • Available only for computers manufactured by Apple • Macintosh operating system has been model for most GUIs

33. Stand-Alone Operating Systems • UNIX • Used by power users because of its flexibility and power • Most versions offer GUI • Available forcomputers of allsizes

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.

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

36. NetWare Designed for client/server networks UNIX / Linux Multi-purposeoperating system Windows Server 2003 Upgrade to Windows 2000 Server • Solaris • Version of UNIX developed by Sun Microsystems • Specifically for e-commerce applications Network Operating Systems • Examples of network operating systems

37. Embedded Operating Systems • Embedded operating system • Found on most mobile computers, PDAs, and other small devices • Windows CE is scaled-down version of Windows

38. Embedded Operating Systems • Operating systems for PDAs • Windows Mobilefor Pocket PC • Palm OS for Palm

39. Embedded Operating Systems • Embedded Linux • Scaled-down Linux operating systemdesigned for PDAs, smart phones,smart watches, set-top boxes,Internet telephones, and otherdevices

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 e-mail and faxes, and more

41. 3.2 Utility Program

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.

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

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

45. OS Utility Program • Uninstaller Removes a program and all associated files In Windows XP, uninstaller is in Add/Remove Programs in Control Panel

46. OS Utility Program • Disk scanner • Detects and corrects problems on hard disk • Searches for and removes unnecessary files

47. fragmented disk disk after defragmentation process OS Utility Program • Disk defragmenter • Reorganizes files and unused space on hard disk so programs run faster

48. OS Utility Program • Diagnostic utility • Compiles technical information about hardware and some software • Prepares report outlining problems

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

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