1. OPERATING SYSTEMS Lecturer: Szabolcs Mikulas Office: B38B
URL:
Textbook:
A.S. Tanenbaum, Modern Operating Systems,
Second edition, Prentice Hall, 2001,
ISBN

2. OUTLINE 1. Introduction 2. Processes and threads 3. Deadlock
4. Memory management
5. Input/output
6. File systems
7. Multimedia operating systems
8. Multiple processor systems
9. Security
UNIX and Windows are to be used as running case studies.

3. Chapter 1 Introduction 1.1 What is an operating system
1.2 History of operating systems
1.3 The operating system zoo
1.4 Computer hardware review
1.5 Operating system concepts
1.6 System calls
1.7 Operating system structure

4. Introduction A computer system consists of hardware system programs
application programs

5. What is an Operating System
It is an extended, or virtual, machine
provides a simple, high-level abstraction, i.e., hides the “messy details” which must be performed
presents user with a virtual machine, easier to use
provides services; programs obtain these by system calls
It is a resource manager
provides orderly and controlled allocation for programs in terms of time and space, multiplexing

6. History of Operating Systems
First generation
vacuum tubes, plug boards
Second generation
transistors, batch systems
Third generation – 1980
ICs and multiprogramming
Fourth generation 1980 – present
personal computers

7. Second Generation Early batch system bring cards to 1401
read cards to tape
put tape on 7094 which does computing
put tape on 1401 which prints output

8. Second Generation (2)
Structure of a typical FMS job – 2nd generation

9. Third Generation Third generation: Multiprogramming Timesharing
MULTICS => UNIX

10. Fourth Generation Fourth generation (1980- ) - Personal computers
MS-DOS,
Graphical User Interface (GUI),
Windows,
Network and distributed OSs

11. The Operating System Zoo
Mainframe operating systems
Server operating systems
Multiprocessor operating systems
Personal computer operating systems
Real-time operating systems
Embedded operating systems
Smart card operating systems

12. Computer Hardware Review
Monitor
Bus
Components of a simple personal computer

13. Processors
(a) A three-stage pipeline
(b) A superscalar CPU

14. Memory
Typical memory hierarchy
numbers shown are rough approximations

15. Structure of a disk drive
Hard Disk
Structure of a disk drive

16. One base-limit pair and two base-limit pairs

17. Interrupt (a) Steps in starting an I/O device and getting interrupt
(b)
(a) Steps in starting an I/O device and getting interrupt
(b) How the CPU is interrupted

18. Structure of a large Pentium system

19. Processes Program in execution
Address space: list of memory locations for read and write - code, data, stack
Process table: one entry for each process,
contains: list of open files,
state
UID etc.
Communication, scheduling

20. A Process Tree A created two child processes, B and C
B created three child processes, D, E, and F

21. (a) A potential deadlock. (b) An actual deadlock.
Read-write example

22. Main Memory Holds executing programs Multiple programs - protection
Large programs - virtual memory

23. File system for a university department

24. Files Abstract model of device independent files
Hierarchy, directories, operations
Absolute and relative path names - root and working directory
Special files (for I/O devices):
block s.f.
character s.f.
Security

25. Mounting Before mounting, After mounting floppy on b,
files on floppy are inaccessible
After mounting floppy on b,
files on floppy are part of file hierarchy

26. Two processes connected by a pipe
e.g. sort <in|head -30

27. System Calls
Interface between OS and user programs (to perform privileged operations)
Machine dependent, but procedure libraries

28. Steps in Making a System Call
There are 11 steps in making the system call
read (fd, buffer, nbytes)

29. Some System Calls For Process Management

30. Some System Calls For File Management

31. Some System Calls For Directory Management

32. Some System Calls For Miscellaneous Tasks

33. Shell A stripped down shell: while (TRUE) { /* repeat forever */
type_prompt( ); /* display prompt */
read_command (command, parameters) /* input from terminal */
if (fork() != 0) { /* fork off child process */
/* Parent code */
waitpid( -1, &status, 0); /* wait for child to exit */
} else {
/* Child code */
execve (command, parameters, 0); /* execute command */ }

34. Link
Link(/usr/jim/memo,/usr/ast/note)
(a) Two directories before linking /usr/jim/memo to ast's directory
(b) The same directories after linking

35. Mount (a) File system before the mount (b) File system after the mount
mount(/dev/fd0,/mnt,0)
(a) File system before the mount
(b) File system after the mount

36. Windows System Calls
Some Win32 API calls

37. Monolithic System
Simple structuring model for a monolithic system

38. Structure of the THE operating system
Layered System
Structure of the THE operating system
MULTICS - concentric rings

39. Structure of VM/370 with CMS
Virtual Machines
Structure of VM/370 with CMS
CMS: Conversational Monitor System
VM: Virtual Machine Monitor - multiprogramming
MS-DOS on Pentium
JVM

40. Exokernels Similar to VM, but Restriction to allocated resources
No need for remap

41. Client-Server Model Microkernel handles communication
provides low-level resource management
Cf. Mechanism versus policy

42. C-S Model in a DS
The client-server model in a distributed system