1. CMPT 300 Day: Operating System Instructor: Senqiang Zhou TA: Rong Ge {szhoua, rge}@cs.sfu.ca

2. 2 What Is This Course About?

3. 3 Office Hours & Places Instructor: Time: Mon. 14:30-15:30 Wed 11:00-12:00 Place: ASB 9911 TA: Time: Tue. 10:00-12:00 Fri. 14:00-15:00 Place: MTF109 North - CSIL Linux Study Area E-MAIL List: cmpt-300-d1@sfu.cacmpt-300-d1@sfu.ca ACS SFU account desk at Strand Hall Course web-page: http://www.cs.sfu.ca/CC/300/szhoua/

4. 4 Grading Four assignments count for 20%. One term project counts for 15%. One 1-hour mid-term exam counts for 20%. Covers Ch 1 to Ch 3. One 3-hour final exam counts for 45%. Covers Ch1 to Ch 6.

5. 5 Pre-requisites C/C++: Necessary for term project Necessary to understand the codes in textbook Basic hardware knowledge: CPU, memory, bus, hard disk, I/O devices Basic data structures: Queue, stack, etc.

6. 6 Chapter 1 Introduction

7. 7 Outline Definitions of operating system History of operating systems Categories of operating systems Computer hardware review Operating system concepts System calls

8. 8 Why Do We Need OS? Many resources Hardware: processors, memory, disks, printers, keyboard, monitors, network interfaces, … Software: compilers, office tools, browsers, games, … Many tasks Programming, surfing web, handling emails, solving equations, playing music, … Many users Share the resources: fairness Vs. Efficiency

9. 9 A Computer Without OS Consider a daily task: read data from diskette Basic commands: 13 parameters Disk address, #blocks to read, #blocks per track…. Controller chips 23 status and error field Do you want to program the hardware directly? A simpler interface is needed!

10. 10 The Benefits of OS Hide the tedious details They are out of the user’s interest E.g., to access data, only need to specify the file name. Provide a variety of services: system calls A set of procedures an be called by programs using special instructions. A simple interface Present key features to programmer Meet requirements from many programs

11. 11 OS As A Virtual Machine Virtual machine/extended machine Hide the underlying hardware Access hardware through a set of system calls Trade-off Higher efficiency in program development and system management More important with complex software Less efficiency in program execution Less important with faster machine

12. 12 OS As A Resource Manager Multiplexing (sharing) resources In time Users/programs take turns using resources CPU, printers, etc. In space Users/programs get parts of resources Main memory, disk, etc. Protecting resources E.g., user’s memory space Issues about a good manager Fairness, efficiency, safety, …

13. 13 What Is An Operating System? Provide user programs with a simpler interface Manage resources Banking system Airline reservation Web browser User programs CompilersEditors Command interpreter System programs Operating system Machine language Hardware Micro-architecture Physical devices

14. 14 Outline What is an operating system? History of operating systems Categories of operating systems Computer hardware review Operating system concepts System calls

15. 15 History of Operating Systems OS and architecture of computers Computer evolves  so does OS To provide better service  OS has impact on computer design Keep evolving through years (1944-) Four generations so far during 60 years Speed, volume, storage, interface… Most important: price keeps dropping How many generations for car industry?

16. 16 The First Generation Computer Vacuum tubes and plug-boards 1944-1955 Huge volumes, slow speed, low stability, expensive! Applications: Straightforward numerical calculations Absolutely no game! Scenario Single group of people designed, built, programmed, operated and maintained a machine All in absolute machine language: no assembly language No operating system People did all the tasks.

17. 17 The Second Generation OS Transistors and batch systems 1955-1965 Applications Scientific and engineering calculation Programming Language: FORTRAN IBM 1401IBM 7094IBM 1401 Cards from programmers Read batch of jobs onto tape Input tape Do computing Output tape Print out

18. 18 Ancestor of Today’s OS Batch system Read a job from tape  run the job  write output onto a output tape Load next job A typical input job: series of commands $JOB  $FORTRAN  $LOAD  $RUN Examples: FMS, IBSYS

19. 19 The Third Generation OS Features: ICs and multiprogramming 1965-1980 Applications Numerical calculations in science & engineering Word-oriented, large-scale scientific computers Massive commercial data processing Character-oriented, commercial computers

20. 20 Key Advances in 3rd Gen OS Multiprogramming Run job 2 while job 1 waiting for I/O Keep CPU busy Spooling Read jobs from cards to disk asap Load new jobs from disk whenever old job done Time sharing CPU is allocated in turn Different from multiprogramming Job 3 Job 2 Job 1 OS Memory partitions

21. 21 Milestones IBM OS/360 M.I.T. CTSS M.I.T. MULTICS Ken Thompson UNIX AT&T UNIX System V UC Berkeley UNIX BSD IEEE POSIX Andrew S. Tanenbaum MINIX Linus Torvalds Linux

22. 22 The Fourth Generation OS Personal computers 1980-now VLSI circuits Cheap: an individual has her own computer Milestones Kildall CP/M for Intel 8080, Z80 MS-DOS/BASIC for IBM PC Engelbart GUI MS Windows, Windows NT UNIX X Windows Network & distributed operating systems

23. 23 Outline What is an operating system? History of operating systems Categories of operating systems Computer hardware review Operating system concepts System calls

24. 24 Categories of OS Mainframe operating systems Server operating systems Multiprocessor operating systems Personal computer operating systems Real-time operating systems Embedded operating systems Smart card operating systems

25. 25 Mainframe Operating Systems Characters of mainframe computers Strong I/O capability, e.g., 1000 disks, TB space High-end servers: web server, B2B server Features of OS Batch (background) Transaction processing (interactive) Timesharing Example: IBM OS/390

26. 26 Server Operating Systems Hardware platforms Very large personal computers or workstations Services Printing File accessing Web Examples UNIX, Windows 2000, Linux

27. 27 Multiprocessor Operating Systems Multiple CPUs within a single system Parallel computers: Local memory, connected via WAN, loosely coupled Multi-computers: Local memory, connected via LAN, tightly coupled Multiprocessors: share memory, connected via BUS Features of OS Variations of the server operating systems Special features for communication and connectivity between CPUs

28. 28 Personal Computer OS User friendly interface Easy to manipulate Abundant application software: word processing, spreadsheets, internet access, game… Examples Windows 98, Windows 2000 Macintosh operating system Linux

29. 29 Outline What is an operating system? History of operating systems Categories of operating systems Computer hardware review Operating system concepts System calls

30. 30 Components of A Computer System bus: connect all components Bus CPUMemory Video controller Keyboard controller Floppy disk controller Hard disk controller Monitor Keyboard Floppy disk driver Hard disk driver I/O Devices

31. 31 CPU (Processor) Basic model Fetching instruction  decoding  executing Different CPUs have different instruction sets. Registers Program counter: pointer to next instruction PSW: program status word Condition code bit, the mode (kernel or user), etc. Stack pointer: point to the top of current stack General registers: hold temporary results

32. 32 Working Modes Two modes in CPU Kernel mode: full capability User mode: I/O, memory protection instructions are disallowed. System calls: get OS service for user program, switch to kernel mode by TRAP instruction. User Program OS User Program System Call Service Done User mode Kernel mode User mode

33. 33 Memory Hierarchy Typical access time Typical capacity 1 nsecRegister<1 KB 2 nsecCache1 MB 10 nsecMain memory64MB-1G 10 msecMagnetic disk5-100 GB 100 secMagnetic tape20-100 GB Reason: Trade off between speed and Cost RAM

34. 34 Memory Management Hold multiple programs in main memory Improve CPU utilization. Why? Problems Protection Program A is not allowed to fetch data within program B Protect kernel from users’ programs Relocation Each program starts from logical address 0 How to load and allocate them into main memory?

35. 35 Base/Limit Registers Base register Point to the start of a program Its content is added to every program address Limit register Record the size of program + data Limit of addresses Virtual address  physical address Base = 4096, limit = 6114 Virtual addr = 2000  physical addr = 2000+4096=6096 < limit, legal! MMU: memory management unit User program and data Operating system 0 Base Limit 0xFFFFFFF

36. 36 Split Program and Data Why: multiple users may run a same program How: base/limit registers for program and data, respectively Overhead of switching: context switch User-2 data User-1 data User program Operating system Base-1 Limit-1 Registers when running program 1 Base-2 Limit-2 Base-2 Limit-2 Registers when running program 2 Base-1 Limit-1