Lecture 6 - Software 2


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Lecture 6 - Software 2

  1. 1. Software - 2 Operating Systems
  2. 2. Objectives <ul><li>The objectives of this session are to: </li></ul><ul><li>Describe what an operating system is; </li></ul><ul><li>Define the main functions of operating systems; </li></ul><ul><li>Describe the leading operating systems in use today; </li></ul><ul><li>Outline current trends in operating system technology. </li></ul>
  3. 3. Operating Systems <ul><li>The operating system ‘runs’ the computer. It is the program used to control the hardware of the computer directly. </li></ul><ul><li>Without such programs the hardware would be useless. </li></ul><ul><li>Systems software is often said to form the bridge between the applications’ software and the hardware. </li></ul>
  4. 4. Operating Systems <ul><li>Operating systems may be: </li></ul><ul><ul><li>Proprietary. </li></ul></ul><ul><ul><li>Open </li></ul></ul><ul><li>There is a shrinking range of operating systems in use today. </li></ul><ul><li>It is important to be aware of: </li></ul><ul><ul><li>the different types of operating system; </li></ul></ul><ul><ul><li>what the leading products are; </li></ul></ul><ul><ul><li>the business implications of selecting different operating systems; </li></ul></ul><ul><ul><li>current trends. </li></ul></ul>
  5. 5. Operating System Services <ul><li>Key services include: </li></ul><ul><ul><li>File/disk management; </li></ul></ul><ul><ul><li>Screen management; </li></ul></ul><ul><ul><li>Recovery; </li></ul></ul><ul><ul><li>Peripheral management; </li></ul></ul><ul><ul><li>Resource management; </li></ul></ul><ul><ul><li>Access and security control . </li></ul></ul><ul><li>We will look at each of these. </li></ul>
  6. 6. OS Services: File/Disk Management <ul><li>Physical location management; </li></ul><ul><li>Housekeeping; </li></ul><ul><li>File names; </li></ul><ul><li>Directories and directory structures; </li></ul><ul><li>Underpinning of other data management systems. </li></ul><ul><li>Maximum number of files supported. </li></ul><ul><li>Compression and fragmentation management </li></ul>
  7. 7. OS Services: File/Disk Management Disk Fragmentation
  8. 8. <ul><li>Text; </li></ul><ul><li>Graphical User Interface (GUI); </li></ul><ul><ul><li>Icons; </li></ul></ul><ul><ul><li>Pull down menus; </li></ul></ul><ul><ul><li>Action buttons; </li></ul></ul><ul><ul><li>Scroll bars; </li></ul></ul><ul><ul><li>Drag and drop. </li></ul></ul>OS Services: Screen Management
  9. 9. OS Services: Screen Management <ul><li>Browser. </li></ul><ul><ul><li>Hypertext linking; </li></ul></ul><ul><ul><li>Action buttons; </li></ul></ul><ul><ul><li>Forms;. </li></ul></ul><ul><li>The GUI is not necessarily part of the O/S </li></ul>
  10. 10. <ul><li>The operating system must manage devices such as: </li></ul><ul><ul><li>Printers; </li></ul></ul><ul><ul><li>Modems; </li></ul></ul><ul><ul><li>Scanners; </li></ul></ul><ul><ul><li>External disk drives; </li></ul></ul><ul><ul><li>CD drives; </li></ul></ul><ul><ul><li>Tape drives; </li></ul></ul><ul><ul><li>Plug and play technology. </li></ul></ul>OS Services: Peripherals
  11. 11. OS Services: Recovery <ul><li>It must handle problems such as </li></ul><ul><ul><li>Crash management; </li></ul></ul><ul><ul><li>File recovery; </li></ul></ul><ul><ul><li>Rollback; </li></ul></ul>
  12. 12. <ul><li>It must handle a variety of security issues: </li></ul><ul><ul><li>Authorised user lists; </li></ul></ul><ul><ul><li>Logon ids; </li></ul></ul><ul><ul><li>Passwords; </li></ul></ul><ul><ul><li>Directory permissions; </li></ul></ul><ul><ul><li>File access permissions: </li></ul></ul><ul><ul><ul><li>Read; </li></ul></ul></ul><ul><ul><ul><li>Write; </li></ul></ul></ul><ul><ul><ul><li>Append; </li></ul></ul></ul><ul><ul><ul><li>Execute. </li></ul></ul></ul><ul><ul><li>Encryption </li></ul></ul><ul><ul><li>Auditing logs </li></ul></ul><ul><ul><li>Accounting logs </li></ul></ul>OS Services: Access and Security Control
  13. 13. OS Services: Resource Management <ul><ul><li>The Operating System must manage the machine resources including : </li></ul></ul><ul><ul><li>Job management and scheduling; </li></ul></ul><ul><ul><li>Resource allocation; </li></ul></ul><ul><ul><li>Conflict resolution; </li></ul></ul><ul><ul><li>Managing the flows of data throughout the system </li></ul></ul><ul><ul><li>Start up and shut down; </li></ul></ul>
  14. 14. Operating Systems Evolution <ul><li>System Developer Approx. Year </li></ul><ul><li>OS/360 IBM 1964 </li></ul><ul><li>Unix Bell Labs 1969 </li></ul><ul><li>VMS Digital 1978 </li></ul><ul><li>DOS Microsoft 1981 </li></ul><ul><li>MacOS Apple 1984 </li></ul><ul><li>OS/400 IBM Mid 1980s </li></ul><ul><li>OS/2 1.0 Microsoft/IBM 1987 </li></ul><ul><li>Windows 3 Microsoft 1990 </li></ul><ul><li>Linux Open Source 1991 </li></ul><ul><li>Windows NT Microsoft 1993 </li></ul><ul><li>Windows 95 Microsoft 1995 </li></ul>
  15. 15. Operating Systems Evolution <ul><li>System Developer Approx. Year </li></ul><ul><li>Windows 98 Microsoft 1998 </li></ul><ul><li>Windows 2000 Microsoft 1999 </li></ul><ul><li>MacOSX Apple 1999 </li></ul><ul><li>Windows XP Microsoft 2001 </li></ul><ul><li>Windows Vista Microsoft 2007 </li></ul>
  16. 16. The Major Operating Systems <ul><li>Outside of the IBM world, there are four key operating systems in use today: </li></ul><ul><ul><li>Linux . </li></ul></ul><ul><ul><ul><li>Open-source alternative to other more expensive operating systems. Gaining popularity. </li></ul></ul></ul><ul><ul><li>Unix </li></ul></ul><ul><ul><ul><li>Dominates large server and scientific/engineering world </li></ul></ul></ul><ul><ul><li>MacOS/ X </li></ul></ul><ul><ul><ul><li>Has about 7-8% of market world-wide. Strong in education, publishing and graphics. </li></ul></ul></ul><ul><ul><li>Microsoft Windows 95/98 , NT, 2000, XP or Vista </li></ul></ul><ul><ul><ul><li>Dominant desktop technology today </li></ul></ul></ul><ul><ul><ul><li>Rising fast in the server market. </li></ul></ul></ul>
  17. 17. Microsoft Windows NT/2000/XP <ul><li>Proprietary </li></ul><ul><li>Low end server and desktop operating systems. </li></ul><ul><li>Primarily 32 bit system </li></ul><ul><li>Supports preemptive multitasking. </li></ul><ul><li>Supports multiprocessing up to a point. </li></ul><ul><li>Memory hungry </li></ul><ul><li>Large storage requirements </li></ul><ul><li>GUI front end </li></ul><ul><li>NT not Plug and Play, 2000/XP is Plug and Play </li></ul>
  18. 18. Microsoft Windows Vista <ul><li>Proprietary </li></ul><ul><li>Released January 2007 </li></ul><ul><li>Biggest upgrade since Windows XP </li></ul><ul><li>Hardware Implications </li></ul><ul><ul><li>At least 1.5 GHz processor </li></ul></ul><ul><ul><li>512 Mb RAM </li></ul></ul><ul><ul><li>Good graphics card (64Mb) </li></ul></ul><ul><ul><li>HD Monitor </li></ul></ul><ul><ul><li>http://www.microsoft.com/windowsvista/default.mspx </li></ul></ul>
  19. 19. Apple MacOS <ul><li>Proprietary </li></ul><ul><li>Currently at version - 10.5 (Leopard) </li></ul><ul><li>64 bit system </li></ul><ul><li>Runs on PowerPC. </li></ul><ul><li>Preemptive multitasking; </li></ul><ul><li>Generally recognised as having the best GUI; </li></ul><ul><li>Windows emulators are available (e.g. Connectix); </li></ul><ul><li>Now limited to a niche market. </li></ul>
  20. 20. Unix <ul><li>Vintage (1969) operating system with many derivatives. </li></ul><ul><li>Both proprietary and open systems available </li></ul><ul><li>Written in the C programming language </li></ul><ul><li>Both 32 and 64 bit versions </li></ul><ul><li>Runs on a vast range of platforms. </li></ul><ul><li>Supports preemptive multitasking. </li></ul><ul><li>Supports multiprocessing. </li></ul><ul><li>Stable </li></ul><ul><li>Free versions such as Linux available and spreading rapidly. </li></ul><ul><li>Problem with standardisation </li></ul><ul><li>X Windows </li></ul>
  21. 21. Linux <ul><li>Developed in early 1990s as an alternative for MS Windows </li></ul><ul><li>Open system </li></ul><ul><li>Runs on a vast range of platforms. </li></ul><ul><li>Both 32 and 64 bit versions. </li></ul><ul><li>Supports up to 4 processors. </li></ul><ul><li>Stability, security and remote management </li></ul><ul><li>Applications becoming available </li></ul><ul><li>Not as user friendly as MS Windows or Mac. </li></ul><ul><li>http://www.ubergeek.tv/article.php?pid=54 </li></ul>
  22. 22. Operating System Hierarchy Mainframe ESA Unix Others Large Server Unix Smaller Server Windows NT /2000 Unix OS/2 Linux Desktop Windows 95/98 Windows 2000 Mac OS Linux Unix
  23. 23. Mobile Device Operating Systems <ul><li>Windows CE </li></ul><ul><li>Pocket PC </li></ul><ul><li>Palm OS </li></ul><ul><li>Embedded Linux – Google’s Android </li></ul>
  24. 24. Operating Systems <ul><li>Provide an interface between application programs and the hardware. </li></ul><ul><li>Steady move away from mainframes. </li></ul><ul><li>Increasing standardisation. </li></ul><ul><li>Consolidation is occurring: </li></ul><ul><ul><li>Proprietary systems disappearing </li></ul></ul><ul><ul><li>Microsoft building long term dominance. </li></ul></ul><ul><ul><li>IBM dominate mainframe world. </li></ul></ul><ul><ul><li>Apple very much at a cross-roads </li></ul></ul><ul><ul><li>UNIX for high end servers </li></ul></ul><ul><ul><li>Linux serious contender for Microsoft? </li></ul></ul>
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