Operating System

1. AJAZ KHAN BAIG
OPERATING SYSTEM
Class : BSSE SEMESTER 4
Credit Hours ( 3+1)

2. ATTENDENCE 80% IS MANDATORY FOR FINAL EXAM
GRADING STRUCTURE
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EXAMS %
ASSIGNMENTS(4) 10
QUIZZES(4) 10
MID TERM EXAM 30
FINAL EXAM 50

3. NOT ALLOWED:
Talking with others which causes disturbance
Eating /drinking in class
Can’t leave class without permission
Can’t use mobile phone in class or out of class
during class hours
CLASS RULES
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4. 1 INTODUCTION TO OS, 16 SCHEDULER ALGORITHM
2 COMPUTER SYSTEM ORANIZATION 17 DEADLOCKS
3 COMPUTER HARDWARE OVERVIEW 18 FILE SYSTEM MANAGMENT
4 OS STRUCTURE 19 DATA STRUCTURE OF FILE MANAGMENT
5 OS ENVIRONMENTS 20 DISK STORAGE
6 TYPES OF I/O COMTROLLERS 21 STORAGE MANAGMENT
7 HARDWARE PROTECTION ISSUES 22 MEMORY MANAGEMENT
8 SYSTEM CALLS AND DEVICE DRIVERS 23 DATA STRUCTURE RELATED TO MEMORY
MANAGEMENT
9 PROCESSES, MANAGEMENT, MODELS, ALGOS 24 PAGING
10 IMPLEMENTATION OF PROCESSES 25 SEGMENTATION
11 MODELING MULTIPROGRAMMING 26 SECURITY, SECURITY ISSUES IN OS
12 THREADS 27
13 IMPLEMENTING THREADS 28
14 INTER PROCESS COMMUNICATION 29
15 CPU SCHEDULING, TYPES OF SCHEDULERS 30
COURSE OUTLINE
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INTORDUCION TO OPERATING SYSTEM
Lecture # 1
overview
BOOK:
Operating System Concepts
by Silberschatz and Galvin , 8th
Edition

6.  What is OS
 OS Organization
 Different Definitions of OS
 Computer hardware overview
 OS brief History
 Overview of:
 OS Structure
 Types of OS
 Functions/Goals of OS
 Services of OS
 Computing environments
Key Learning Points
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7. Act as intermediary between User, and
computer H/W
Set of programs for interaction with user
program and hard ware.
Make computer system convenient to use
Use of hardware in an efficient manner
OPERATING SYSTEM ????
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8. An operating system is a program that acts as an interface between the
user and the computer hardware and controls the execution of all kinds
of programs .
It provides an environment for other programs to do useful work.
Resource allocator – manages and allocates resources to the user
programs
Control program – controls the execution of user programs and
operations of I/O devices .
Kernel – the one program running at all times (all else being
application programs)
OS DEFFINITIONS
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9. HARDWARE
 Input hardware (mouse, keyboard, CPU)
 Output hardware (Monitor, Printer)
SOFTWARE
 SYSTEM SOFTWARE(OS AND UTILITY S/W)
 USER/APPLICATION SOFTWARE
COMPUTER
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System Software Application Software
Operating system(Windows, Linux ) MS Office
Assembler Paint
Compiler Multimedia players
Linker Database
Interpreter Image processing tools(Photoshop, Coral
Draw etc.)
loader Programming tools(Netbeans, Java etc.)

10.  Hardware – provides basic computing resources (CPU,
memory, I/O devices).
 Operating system – controls and coordinates the use of the
hardware among the various application programs for the
various users.
 Applications programs – define the ways in which the system
resources are used to solve the computing problems of the
users
 Users (people, machines, other computers).
COMPUTER SYSTEM COMPONENTS
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11. OPERATING SYSTEM BOOTSTAP
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12. Assume we are using MS-Paint over Windows -
when do we need to access the OS?
 Loading the application / terminating the application
 Memory allocation / management
 Access to IO devices – keyboard, mouse, printer,
monitor
 CPU allocation
 Copy / Paste (inter-process communication)
EXAMPLE:
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14. COMPUTER SYSTEM ORGANIZATION
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User
programs

15. USER VIEW OF COMPUTER SYSTEM
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16. Computer-system operation
 One or more CPUs, device controllers connect through common
bus providing access to shared memory
 Concurrent execution of CPUs and devices competing for memory
cycles (through memory controller)
Hardware Architecture
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17.  I/O devices and the CPU can execute concurrently
 Each device controller is in charge of a particular device
type
 Each device controller has a local buffer
 CPU moves data from/to main memory to/from local
buffers
 I/O is from the device to local buffer of controller
 Device controller informs CPU that it has finished its
operation by causing an interrupt
COMPUTER SYSTEM OPERATION
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18.  Memory Management
 Processor Management
 Device Management
 File Management
 Security
 Control over system performance
 Job accounting
 Error detecting aids
 Coordination between other software and users
 Efficient use of computer resources
FUNCTIONS/GOALS OF AN OS
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19.  MEMORY:
Main memory is a large array of words
Has its own address
Fast storage, access directly by the CPU.
 Memory management activities
 Keeps tracks of primary memory
 Decides which process will get memory
 when and
 how much
 Allocates the memory when the process requests
 De-allocates the memory
MEMORY MANAGMENT
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20. OS decides which process gets the processor
when and how much time called
Process scheduling
Activities:
 Keeps tracks of processor
 Status of process
 Allocates the processor(CPU) to a process.
 De-allocates processor when processor is no longer required
PROCESSOR MANAGEMENT
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21. OS manages device communication via drivers.
Operating
Activities for device management.
 Keeps tracks of all devices. Program responsible for this task is
known as the I/O controller.
 Decides which process gets the device
 Allocates the device in the efficient way.
 De-allocates devices
DEVICE MANAGEMENT
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22. File system is organized into directories
Activities for file management
Keeps track of information,
 location
 uses
 status etc.
Decides who gets the resources.
Allocates the resources.
De-allocates the resources.
FILE MANAGEMENT
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23. Security – defense of the system against internal and external attacks
 Huge range, including denial-of-service, worms, viruses, identity
theft, theft of service
Systems generally first distinguish among users, to determine who can
do what
 User identities (user IDs, security IDs)
 User ID then associated with all files, processes of that user to
determine access control
 Group identifier (group ID) allows set of users to be defined and
controls managed,
 then also associated with each process, file
Protection
 Any mechanism for controlling access of processes or users to
resources defined by the OS
SECURITY AND PROTECTION
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24. Control over system performance --
 Recording delays between request for a service and response from the
system.
Job accounting --
 Keeping track of time and resources used by various jobs and users.
Error detecting aids --
 Production of dumps, traces, error messages and other debugging and error
detecting aids.
Coordination between other software and users
 Coordination and assignment of compilers, interpreters, assemblers and
other software to the various users of the computer systems
Efficient use of computer resources
OTHER GOALS
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25. 
Program execution
 I/O operations
 File System manipulation
 Communication
 Error Detection
 Resource Allocation
 Protection
OPERATING SYSTEM SERVICES
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26. Batch processing:
Types Of Operating System
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27. Mainframe Systems:
Reduce setup time by batching similar jobs
 Automatic job sequencing – automatically transfers
control from one job to another.
Resident monitor
 initial control in monitor
 control transfers to job
 when job completes control transfers pack to monitor
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28. Multitasking:
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29. Multi-programmed Batch Systems
 Several jobs are kept in main memory at the same time
 and the CPU is multiplexed among them.
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30. Multiprogramming:
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31. OS Features Needed for Multiprogramming:
 I/O routine supplied by the system.
 Memory management – the system must allocate the
memory to several jobs.
 CPU scheduling – the system must choose among several
jobs ready to run.
 Allocation of devices
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32. An operating system is a program that manages the computer
hardware. It also provides a basis for application programs and
acts as an intermediary between the computer user and the
computer hardware. An amazing aspect of operating systems is
how varied they are in accomplishing these tasks. Mainframe
operating systems are designed primarily to optimize utilization
of hardware.
Because an operating system is large and complex, it must be
created piece by piece. Each of these pieces should be a well-
delineated portion of the system, with carefully defined inputs,
outputs, and functions.
Summary:
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33. Operating system components:
 Hardware
 Operating system
 Applications programs
 Users
Computer system organization
 Applications
 User program
 Utilities
 Operating system
 hardware
Hardware Architecture
Key learning Points
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34. Goals or function of OS
 Memory Management
 Processor Management
 Device Management
 File Management
 Security
 Control over system performance
 Job accounting
 Error detecting aids
 Coordination between other software and users
 Efficient use of computer resources
 Memory management – the system must allocate the memory to several
jobs.
 CPU scheduling – the system must choose among several jobs ready to run.
Key Terms
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35. https://www.youtube.com/watch?
v=nZRqPctQf8U&list=PLTZbNwgO5ebqnympIYe2GX4
hjjsS9Psdm
Video Link
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