1. System Software

2.  System software includes all of the programs needed to keep a computer and its peripheral devices running smoothly  Two major categories of system software are: ◦ Operating systems ◦ System utilities © Prentice-Hall, Inc

3.  The operating system (OS) is a set of programs that perform certain basic functions with a specific type of hardware  Examples of functions of the OS are: ◦ Starting the computer ◦ Managing programs ◦ Managing memory ◦ Managing files ◦ Handling messages from input and output devices ◦ Enabling user interaction with the computer © Prentice-Hall, Inc

4.  OS stays behind the scenes  All software depends on the OS © Prentice-Hall, Inc OperatingSystem GUI

5.  Resource allocation ◦ Assigning computer resources to certain programs and processes for their use  Main issues related to resource allocation ◦ Sharing the Central Processing Unit (CPU) ◦ Sharing memory ◦ Sharing storage resources ◦ Sharing printing resources © Prentice-Hall, Inc

6.  Multiprocessing  Multiprogramming  Time-Sharing © Prentice-Hall, Inc

7.  The use of a powerful computer with multiple CPUs  Multiple programs run simultaneously ◦ Each runs on its own processor © Prentice-Hall, Inc

8.  Two or more programs executed concurrently ◦ Programs take turns using the CPU ◦ Event-driven  An interrupt suspends processing to allow another program to run  After the second program runs, the OS returns the CPU to another program © Prentice-Hall, Inc

9.  Programs take turns using the CPU  Time-driven ◦ Each user is given a slice of time (fraction of a second) ◦ CPU works only on that user’s tasks during his/her time slice  Typically used in applications with many users © Prentice-Hall, Inc

10.  Single-tasking systems run one application program at a time  Multitasking OSs have the ability to run more than one application program at a time  Multitasking is accomplished by ◦ A foreground application  The active program or program in use ◦ One or more background applications  Inactive program(s) or program(s) not in use © Prentice-Hall, Inc

11. Background application Foreground application © Prentice-Hall, Inc

12.  Access Windows Task Manager by pressing Ctrl + Alt + Del, select the Start Task Manager option, and then click the Processes tab

13.  First review Von-Neumann architecture ◦ System component: CPU, Memory and IO ◦ Programs must be in main memory (RAM) to execute ◦ cycle under Von-Neumann architecture  Load instruction from memory into instruction register  Operands fetched from memory to internal registers START Fetch next instruction from Memory to IR, Increment PC Decode Instruction and fetch data if needed Execute Instruction in IR STOP ? NO YES

14.  Ideally, we want programs and data to reside in main memory permanently ◦ Main memory is usually too small ◦ Main memory is volatile – loses contents on power loss  Secondary storage holds large quantities of data, permanently ◦ Magnetic disk is the most common secondary- storage device ◦ Actually, a hierarchy of storage varying by speed, cost, size and volatility © Prentice-Hall, Inc

16.  The operating system allocates memory areas for each running program; it keeps programs from interfering with each other  The operating system uses virtual memory as an extension of random access memory (RAM) © Prentice-Hall, Inc

17. least recently used data or program instructions page swapped out swap file Virtual memory management hard disk page swapped in most recently transferred data or program instructions memory Paging: The process of transferring files from the hard disk to RAM and back

18.  You are going to do some research on a particular topic. Thus, you go to the library and look for the a shelve that contains books on that particular topic  You pick up a book from the shelve, find a chair, seat and start reading © Prentice-Hall, Inc

19.  You find a reference to another book on the same topic that you are also interested in reading. Thus, you stand up, go to the same shelve, leave the first book and pick up the other book  Then, you go back to the chair and start reading the second book  Later on you realize that you want to read the first book once again (or another related book). Thus, you repeat the same process (i.e., go to the shelve to find it) © Prentice-Hall, Inc

20.  Suppose that instead of taking just one book from the shelve, you take 10 books on the same topic. Then, you find a table with a chair, put the 10 books on the table, sit there and start reading one of the books  If you need another related book, there is a good chance that it is on your table so you don’t have to go to the shelve to get it. Also, you can leave the first book on the table and there is a good chance that you will be needing it again later © Prentice-Hall, Inc

21.  cache are relatively smaller and faster to access compared to main memory  Data are transfer to cache with the hope that future requests for that data can be served faster © Prentice-Hall, Inc

22.  Input and output devices generate interrupts, or signals, that tell the operating system that something has happened  The OS provides interrupt handlers or mini- programs that begin when an interrupt occurs © Prentice-Hall, Inc

23. Discovering Computers 2012: Chapter 8 23 Page 408

24.  The user interface is that part of the OS with which the user interacts with a computer © Prentice-Hall, Inc

25.  Graphical user interface (GUI) ◦ Uses graphics to create a desktop environment ◦ Icons (small pictures) represent computer resources ◦ Programs run within on-screen windows  Menu-driven ◦ Text-based menus are used to show all of the options available to the user  Command-line ◦ The user is required to type keywords or commands in order to enter data or give instructions © Prentice-Hall, Inc

29.  Operating systems typically provide a means to establish Internet connections Discovering Computers 2012: Chapter 8 29 Page 408 Figure 8-10

30.  A performance monitor is a program that assesses and reports information about various computer resources and devices Discovering Computers 2012: Chapter 8 30 Pages 408 – 409 Figure 8-11

31.  Automatic update automatically provides updates to the program Discovering Computers 2012: Chapter 8 31 Page 409 Figure 8-12

32.  Booting – The process of loading or reloading the OS into the computer’s memory © Prentice-Hall, Inc

33.  The computer copies the kernel from the hard drive into the computer’s memory ◦ The kernel  Is the central part of the OS  Starts all applications  Manages devices and memory  Resides in memory at all times  Performs other essential functions © Prentice-Hall, Inc

34.  Six steps to starting a computer:

35.  Activate BIOS and Setup Program  BIOS: Basic input/output system  POST: Power on self-test

37.  Sleep state: Transfers the current state of computer to RAM  Hibernate state: Saves battery power  Hybrid sleep state: Combines sleep and hibernate

38.  Account: User name, password, and allotted storage space  Multitasking operating systems: Permit more than one application to run at the same time and can manage multiple applications running simultaneously

39. Discovering Computers 2012: Chapter 8 39 Page 409 Managing files Searching for files Viewing images Securing a computer Uninstalling programs Cleaning up disks Defragmenting disks Diagnosing problems Backing up files and disks Setting up screen savers

40. © Prentice-Hall, Inc MS-DOS WINDOWS XP MAC OS LINUX UNIX

41. © Prentice-Hall, Inc Windows 1.0 (1985)Windows 2.0 (1987)Windows 3.x (1990-1992)Windows NT (1993)Windows 95 (1995)Windows 98 (1998)Windows 2000 (2000)Windows ME (2000)Windows 7

42.  Created in 1984  First OS to use graphical user interface  Easiest operating system for beginners  A new version, Mac OS X, was released in 2000 © Prentice-Hall, Inc

43.  Developed for IBM PCs in 1981  Uses command-line interface  Use is diminishing © Prentice-Hall, Inc

44.  Developed by AT&T in 1970s  Developed concepts of file management and path names  Multitasking OS © Prentice-Hall, Inc

45.  Developed in 1991  Open-source code –Available for all to see and use  UNIX typed, More stable than Windows  Powerful and free  Growing acceptance © Prentice-Hall, Inc

46.  An embedded operating system resides on a ROM chip on a mobile device or consumer electronic device Discovering Computers 2012: Chapter 8 46 Pages 418 - 420 Windows Embedded CE Windows Phone 7 Palm OSiPhone OS BlackBerry Google Android Embedded Linux Symbian OS

47. Discovering Computers 2012: Chapter 8 47 Pages 419 – 420 Figures 8-22 – 8- 26

48.  A utility program is a type of system software that allows a user to perform maintenance-type tasks Discovering Computers 2012: Chapter 8 48 Page 421 Figure 8-27 Backup software Antivirus software Disk scanning Disk defragmentation File compression Etc.

49.  A backup utility allows users to copy files to another storage medium  A restore utility reverses the process and returns backed up files to their original form Discovering Computers 2012: Chapter 8 49 Page 424 Figure 8-33

50.  Antivirus software protects the computer from computer viruses © Prentice-Hall, Inc

51. A virus describes a potentially damaging computer program that affects a computer negatively A worm copies itself repeatedly in memory or over a network A Trojan horse hides within or looks like a legitimate program An antivirus program protects a computer against viruses Discovering Computers 2012: Chapter 8 51 Pages 425 - 426

52. Discovering Computers 2012: Chapter 8 52 Pages 425 – 426 Figures 8-36 – 8- 37

53. Spyware is a program placed on a computer without the user’s knowledge that secretly collects information about the user A spyware remover detects and deletes spyware and other similar programs Adware displays an online advertisement in a banner or pop-up window An adware remover is a program that detects and deletes adware Discovering Computers 2012: Chapter 8 53 Page 426

54.  Filters are programs that remove or block certain items from being displayed Discovering Computers 2012: Chapter 8 54 Pages 426 - 427 Web filtering software Anti-spam programs Phishing filters Pop-up blockers

55.  Known as a file manager  Enables the user to perform various tasks on storage devices using files, folders, and directories  Tasks include: ◦ Creating folders ◦ Saving, deleting, copying, and moving files and folders ◦ Examining the contents of files ◦ Launching application programs © Prentice-Hall, Inc

56.  Search programs enable users to find files on storage devices © Prentice-Hall, Inc

57.  Computer startup failure ◦ Use a boot disk (emergency disk) in the floppy drive  System slowdown ◦ Scan for viruses ◦ Defragment the hard disk © Prentice-Hall, Inc

58.  A disk defragmenter reorganizes the files and unused space on a computer’s hard disk so that the operating system accesses data more quickly and programs run faster ◦ Defragmenting Discovering Computers 2012: Chapter 8 58 Pages 423 – 424 Figure 8-32

59.  A screen saver causes a display device’s screen to show a moving image or blank screen if no activity occurs for a specified time  A personal firewall detects and protects a personal computer from unauthorized intrusions Discovering Computers 2012: Chapter 8 59 Page 425 Figures 8-34 – 8- 35

60.  A file compression utility shrinks the size of a file(s) ◦ Compressing files frees up room on the storage media ◦ Two types of compression  Lossy  Lossless  Compressed files sometimes are called zipped files ◦ Can be uncompressed Discovering Computers 2012: Chapter 8 60 Page 427

61.  A media player allows you to view images and animation, listen to audio, and watch video files on your computer Discovering Computers 2012: Chapter 8 61 Page 427 Figure 8-38

62.  Disc burning software writes text, graphics, audio, and video files on a recordable or rewritable optical disc Discovering Computers 2012: Chapter 8 62 Page 428 Figure 8-39

63.  A personal computer maintenance utility identifies and fixes operating system problems, detects and repairs disk problems, and includes the capability of improving a computer’s performance Discovering Computers 2012: Chapter 8 63 Page 428 Figure 8-40

64.  Archive: Single file that contains two or more files stored in a compressed format along with additional information  Windows Update: Keeps the operating system up to date with fixes; also called service packs  File compression utility: Enables the exchange of programs and data efficiently by reducing the size of a file

65.  Safe mode: Operating mode in which Windows loads a minimal set of drivers known to function correctly