COSC1078 Introduction to Information Technology Lecture 14 Operating Systems

1. Intro to IT James Harland james.harland@rmit.edu.au COSC1078 Introduction to Information TechnologyLecture 14Operating Systems

2. Intro to IT Introduction • James Harland • Email:james.harland@rmit.edu.au • URL:www.cs.rmit.edu.au/~jah • Phone:9925 2045 • Office:14.10.1 • Consultation:Mon 4.30-5.30, • Thu 11.30-12.30 • What colour is my office door? Carpet? Chair?

3. Intro to IT Introduction to IT 1 Introduction 2Images 3Audio 4Video WebLearnTest 1 5 Binary Representation Assignment 1 6 Data Storage 7Machine Processing 8 Operating Systems WebLearn Test 2 9 Processes Assignment 2 10 Internet 11Internet Security WebLearn Test 3 12Future of IT Assignment 3, Peer and Self Assessment

4. Intro to IT Overview • Questions? • Assignments 1 & 2 • Operating Systems • Questions?

5. Assignments 1& 2 Assignment 1 Currently being marked Will have marks out later this week Assignment 2 Specification has been published Must be done in groups of 2 or 3 Can change groups from Assignment 1 (if you wish) Must have a blog on Blackboard Lecture 14: Operating Systems Intro to IT

6. Questions? How did you spend 6-8 hours on this course last week? This week? Lecture 14: Operating Systems SE Fundamentals

7. Intro to IT Operating Systems kernel operating system device driver open source real time virtual machine desktop publishing

8. Intro to IT Operating Systems Operating system

9. Intro to IT Operating Systems • Manage hardware and software resources • Memory allocation • Prioritising requests and processes • Controlling input and output devices • Managing network access • Managing file systems • Dealing with multiple users • …

10. Intro to IT Operating Systems USER HARDWARE HARDWARE

11. Intro to IT Operating Systems

12. Intro to IT Operating Systems • Concurrent execution of processes on a single CPU • Memory management • Registers, caches, RAM, hard disk, plug-ins, ... • Movement of data between these • File systems • Networking • Printers, scanners, LAN, wireless, Internet, ...

13. Intro to IT Operating Systems • Graphical User Interface (GUI)‏ • Colors, data, cursors, ... • Device drivers • Code specialised for particular hardware device (DVD writer, printer, monitor, ...)‏ • Controls access to these • Security • Passwords, file sharing, protocols, ...

14. Intro to IT Operating Systems • Desktop (Windows, MacOS, Linux, ... )‏ • Windows around 85% of market • Server systems • Google “back end”, server farms, ... • Windows Server or Unix • Specialist systems • Supercomputers, call centres, real-time systems, PDA systems, ...

15. Intro to IT Operating Systems

16. Intro to IT Linux • Open source • Developed in 1991 by LinusTorvalds • Written in C • RedHat, Mandrake, SUSE, Ubuntu, ... • RedHat 7.1 has 30 million+ lines of code

17. Intro to IT Windows • Add-on to MS-DOS in 1985 • Most popular OS • Known security issues • Windows XP 40 million lines of code • Vista released 2007 • Windows 7 (now!)

18. Intro to IT MacOS • Only on Apples • Introduced by Apple in 1984 • GUI from the start • Based on Unix • Graphics features • Mac OS X Leopard

19. Where to begin? • How do you start an operating system? • Boot it! (or bootstrap) • Turn on power () • Machine loads bootstrap program from ROM (non-volatile memory) • Bootstrap program loads OS • OS takes over Lecture 14: Operating Systems Intro to IT

20. Initial State When Turned On Processor Memory Disk ROM 00 00 Bootstrap Program Program Counter RAM Instruction Register Lecture 14: Operating Systems Intro to IT

21. Load Bootstrap Program Processor Memory Disk ROM 00 00 Bootstrap Program Program Counter RAM Instruction Register Lecture 14: Operating Systems Intro to IT

22. Bootstrap program loads OS Processor Memory Disk ROM 00 00 Bootstrap Program Program Counter RAM Instruction Register Lecture 146: Operating Systems Intro to IT

23. Bootstrap program loads OS Processor Memory Disk ROM 00 00 Bootstrap Program Program Counter RAM Instruction Register Lecture 14: Operating Systems Intro to IT

24. Bootstrap program has loaded OS Processor Memory Disk ROM AA 00 Bootstrap Program Program Counter AA RAM Instruction Register Lecture 14: Operating Systems Intro to IT

25. OS takes over execution Processor Memory Disk ROM AA 00 Bootstrap Program Program Counter AA RAM Instruction Register Lecture 14: Operating Systems Intro to IT

26. Starting Up Operating Systems Processor Memory Disk ROM AA 00 Bootstrap Program Program Counter AA RAM Instruction Register Lecture 14: Operating Systems Intro to IT

27. Starting Up Operating Systems Processor Memory Disk ROM AA 00 Bootstrap Program Program Counter AA RAM Instruction Register Lecture 14: Operating Systems Intro to IT

28. Starting Up Operating Systems Processor Memory Disk ROM AA 00 Bootstrap Program Program Counter AA RAM Instruction Register Lecture 14: Operating Systems Intro to IT

29. Multiple boot scenario … Processor Memory Disk ROM 00 00 Bootstrap Program Program Counter RAM Instruction Register Lecture 16: Operating Systems Intro to IT

30. Multiple boot scenario … Processor Memory Disk ROM 00 00 Bootstrap Program Program Counter RAM Instruction Register Lecture 16: Operating Systems Intro to IT

31. Multiple boot scenario … Processor Memory Disk ROM 00 00 Bootstrap Program Program Counter RAM Instruction Register Lecture 16: Operating Systems Intro to IT

32. Multiple boot scenario … Processor Memory Disk ROM 00 00 Bootstrap Program Program Counter RAM Instruction Register Lecture 14: Operating Systems Intro to IT

33. OS Software Classification Software Application System Utility Operating System Shell Kernel Lecture 14: Operating Systems Intro to IT

34. Processes Lecture 16: Operating Systems Intro to IT

35. Processes A program is astatic set of instructions A processes is the execution of a program, which changes state over time. Lecture 14: Operating Systems Intro to IT

36. Processes Executing in Context Processor Memory Disk ROM CC 00 Program Counter RAM CC Instruction Register Lecture 14: Operating Systems Intro to IT

37. Processes Executing in Context Processor Memory Disk ROM DD 00 Program Counter RAM CC DD Instruction Register Lecture 14: Operating Systems Intro to IT

38. Processes Switching Scheduler maintains process table Ready Ready Waiting Lecture 14: Operating Systems Intro to IT

39. Processes Switching Lecture 14: Operating Systems Intro to IT

40. Interrupts • Signals to the CPU • Often generated by timing circuits • CPU reacts by jumping to appropriate memory location • Dispatcher • selects a ready process • resets timing circuit • starts process • CPUs often designed to switch process states efficiently Lecture 14: Operating Systems Intro to IT

41. Processes Executing in Context Processor Memory Disk 00 BB ROM Program Counter RAM BB Instruction Register Lecture 14: Operating Systems Intro to IT

42. Processes Executing in Context Processor Memory Disk 00 11 ROM Program Counter RAM BB Instruction Register Lecture 14: Operating Systems Intro to IT

43. Processes Executing in Context Processor Memory Disk 00 FF ROM Program Counter RAM FF Instruction Register Lecture 14: Operating Systems Intro to IT

44. Interrupts • Provide mechanism to switch processes • CPU doesn’t have to wait for I/O transfers • Switching leads to faster throughput • `Save document’ means CPU does something else while the save takes place Lecture 146: Operating Systems Intro to IT

45. Intro to IT Conclusion • Work on Assignment 2 • Web Quizzes and Web Test 2 • Finish reading book!