1. Chapter 3: Operating Systems

2. Tomorrow 18 Dec 2017 Lecture 9:30 – 12:30 Dish Party
Bring yourself
Bring something delicious
Renew intention
Help preparing
Have manners and politeness
Winners of 500 term competition

3. After Tomorrow 19 Dec 2017 Lecture 11:30 – 12:30
Replacement midterm for late coming students

4. Chapter 3: Operating Systems
3.1 The History of Operating Systems
3.2 Operating System Architecture
3.3 Coordinating the Machine’s Activities
3.4 Handling Competition Among Processes
3.5 Security

5. What are operating systems
Operating systems are software packages that coordinate a computer’s internal activities as well as oversee its communication with the outside world.
It transforms the computer hardware into a useful tool.
Our goal is to understand what operating systems do and how they do it.

6. OS Relation to Other SW Computer Applications: Operating System: Excel
Windows
Linux
Andoid
Applications:
Excel
Game
Browser
VoIP

7. Functions of Operating Systems
Interact with the user
Oversee operation of computer
Store and retrieve files
Schedule programs for execution
Coordinate the execution of programs

9. Popular Operating Systems
MS Windows
Linux
Unix
Mac OS
Android

11. Smart Phone OS

12. Smart Phone OS

14. Evolution of Shared Computing
First Generation: Batch processing
Second Generation: Interactive processing
Requires real-time processing
Third Generation: Time-sharing/Multitasking
Implemented by Multiprogramming
Multiprocessor machines

16. Figure 3.1 Batch processing

17. Figure 3.2 Interactive processing

18. Important Terms operating system job job Queue batch processing
interactive processing
time-sharing
multi-programming - time slice
multi-tasking

20. Types of Software Application software System software
Performs specific tasks for users
System software
Provides infrastructure for application software
Consists of operating system and utility software

21. Figure 3.3 Software classification

22. Utility Programs Includes many kinds: Drivers Anti Virus
Compression (Win Zip)
Defragmentation
Backup

24. 2. Operating System Components
User Interface: Communicates with users
Text based (Shell)
Graphical user interface (GUI)
Kernel: Performs basic required functions
File manager
Device drivers
Memory manager
Scheduler and dispatcher

25. Figure 3.4 The user interface act as an intermediary between users and the operating system kernel

26. Important Terms Aystem software Application software Utility software
Linux
Linus Torvalds
User interface
shells
GUI
Windows manager
Kernel

28. File Manager
Directory (or Folder): A user-created bundle of files and other directories (subdirectories)
Directory Path: A sequence of directories within directories
F:\Data\CS111\Slides

29. Memory Manager Allocates space in main memory
May create the illusion that the machine has more memory than it actually does (virtual memory) by playing a “shell game” in which blocks of data (pages) are shifted back and forth between main memory and mass storage

31. Getting it Started (Bootstrapping)
Boot loader: Program in ROM (example of firmware)
Run by the CPU when power is turned on
Transfers (copies) operating system from mass storage to main memory
Executes jump to operating system

33. Figure 3.5 The booting process

35. 3. Processes Process: The activity of executing a program
Process State: Current status of the activity
Program counter
General purpose registers
Related portion of main memory

36. Process Administration
Scheduler: Adds new processes to the process table and removes completed processes from the process table
Dispatcher: Controls the allocation of time slices to the processes in the process table
The end of a time slice is signaled by an interrupt.

38. Figure 3.6 Time-sharing between process A and process B

40. 5. Securing IT Systems

41. Securing IT Systems

42. Securing IT Systems
Ove
Overflow
Input Injection
Weak
Authentication

43. Securing IT Systems Ove Input Injection Weak Overflow Authentication
Social
Engineering

44. Computer Viruses
It is a program that copies itself repeatedly without the user’s permission and moves from a machine to another through computer networks
It has harmful effect like slowing the machine, damaging data, or even physical damage. (Stuxnet)

45. Types of Computer Viruses
Boot Sector Viruses
File Infectors
Time Bombs
Trojan Horses
Ransomware

46. Fighting Computer Viruses
Do not open unknown messages or attachments
Check attachments before downloading them
Install Anti Virus SW
Scan flashes, etc.

47. Attack 1: Wanna Cry

48. Ransomware
“Ransomware is a computer worm that encrypts the data in the infected computer and makes it unusable as if data is taken as a hostage. Then it displays demands to pay ransom money to release and decrypt the data so it is usable again.”

49. Attack 2: Stuxnet - 1
“Stuxne was a landmark in the history of computer viruses. It is the first virus in history that crosses the boundaries between the digital world and the physical world. Rather than simply hijacking targeted computers or stealing information from them, it caused physical destruction of the equipment the computers controlled, the centrifuges.”

50. Stuxnet - 2 Natanz Centrifuges Remote Server Internet
Control Computers PLCs
Natanz
Remote Server
Internet

51. Important Terms System software Application software Utility software
Linux
Linus Torvalds
User interface
shells
GUI
Windows manager
Kernel
File manager
operating system
job
job Queue
batch processing
interactive processing
time-sharing
multi-programming - time slice
multi-tasking

52. Important Terms boot loader booting directory or folder ROM
process
process state ->
program counter
+ registers
+ memory cells
peripheral devices
MS Windows Task Manager
directory or folder
directory path
device drivers
memory manager
paging - page
virtual memory
scheduler
+ process table
dispatcher
+ time slice
+ process switching
+ interrupt

53. Important Terms
System crash
Administrator
Account
Login