2. WHAT IS AN OPERATING SYSTEM?
 Its is a collection of software that
manages computer hardware
resources and provides common
services for computer programs.
 A vital component of the system
and operates all other program
software in a computer system.
 It was developed for better
computer usage and providing
better platform to the users
application.

3. CLASSIFICATION OF OS
 Multi-user: Allows two or more
users to run programs at the
same time.
 Multiprocessing: Supports
running a program on more than
one CPU.
 Multitasking: Allows more than
one program to run concurrently.
 Multithreading: Allows different
parts of a single program to run
concurrently.
 Real time: Responds to input
instantly. General-purpose
operating systems, such as DOS
and UNIX, are not real-time.
FIG 1: multi-user OS
FIG 2: multiprocessing OS

4. ROLE OF OPERATING SYSTEM
 Management of the processor - Scheduling algorithm.
 Management of the random access memory(RAM) – Virtual
memory.
 Management of input/output - Peripheral administrators or
input/output administrators.
 Management of execution of applications - Allocating the
resources required.
 Management of authorizations - Security relating to execution of
programmers.
 File management - Reading and writing in the file system.
- File access authorizations.
 Information management - Provides a certain number .

5. BOOTSTRAP PROCESS
Booting includes four main steps in computer including power On.
1. Turn on computer .
2. load the initial instructions from the ROM .
3. detect the operating system in the Hard-disk.
4. start the certain essential computer application as per the
default setting.
FIG 3: Bootstrap Steps

6. OS COMPONENTS
The operating system can be broken down into four main parts.
They are:
 Kernel
 Device Drivers
 User Interface
 System Utilities.
KERNEL: kernel handles
 User interface
 Memory management
 Program Execution or process management
 Device management.
 File management
 Data security
FIG 4: Kernel’s Operations

7. USER INTERFACE:
Each operating system has a user interface, a program that
accepts requests from users (processes) and interprets them for
the rest of the operating system. The two most common forms
of a user interface have historically been the command-line
interface, where computer commands are typed out line-by-line,
and the graphical user interface, where a visual environment
(most commonly wimp) is present. A user interface in some
operating systems, such as UNIX, is called a shell. In others, it
is called a window to denote that it is menu driven and has a
GUI (graphical user interface) component.

8. MEMORY MANAGER
 Memory management is the functionality of an operating system
which handles or manages primary memory. Memory
management keeps track of each and every memory location
either it is allocated to some process or it is free. It checks how
much memory is to be allocated to processes. Operating
systems can be divided into two broad categories of memory
management: mono programming and multiprogramming.
FIG 5(a): mono programming FIG 5(b): multiprogramming

9. MULTIPROGRAMMING
 Partitioning: In personal computers, a partition is a
logical division of a hard disk created so that you
can have different operating systems on the same
hard disk or to create the appearance of having
separate hard drives for file management, multiple
users, or other purposes.
 Paging: paging is one of the memory
management schemes by which a computer stores
and retrieves data from the secondary storage for
use in main memory
 Demand paging :its a method of virtual
memory management copies a disk page into
physical memory only if an attempt is made to
access it and that page is not already in memory
(i.e., if a page fault occurs).
 Demand segmentation: it is used when insufficient
hardware to implement demand paging. Segment
descriptor contains a valid bit to indicate whether
the segment is currently in memory.
 If segment is in main memory, access continues,
 If not in memory, segment fault.
FIG 6 : multiprogramming

10. PROCESS MANAGER
 Process management is an integral part of any modern day operating system. It is the
second function of an operating system . The OS must allocate resources to processes,
enable processes to share and exchange information, protect the resources of each process
from other processes and enable synchronization among processes. The relationship
between a program, a job and a process becomes clearer if we consider how a program
becomes a job and how a job becomes a process
 A program is a non-active set of instructions stored on disk.
 A program becomes a job from the moment it is selected for
execution until it has finished running and becomes a program
again.
 A process is a program in execution. It is a program that has started
but has not finished.
Scheduler :To move a job or process from one state to another, the process manager uses two
schedulers: the job scheduler and the process scheduler.
Process synchronization has two problematic situations: deadlock and starvation.
Deadlock: Deadlock occurs when the operating system does not put resource restrictions on
processes.
Starvation: occurs when operating system puts too many resource restrictions on a
process.

11. DEVICE MANGER FILE MANAGER
 Keep tracks of all devices.
Program responsible for
this task is known as the
I/O controller.
 Decides which process
gets the device when and
for how much time.
 Allocate the device in the
efficient ways.
 De-allocates devices
 controls access to files.
 supervises the creation, deletion,
and modification of files.
 controls the naming of files.
 supervises the storage of files.
 is responsible for archiving and
backups.

12. DATA SECURITY
A computer being secure depends on
a number of technologies working
properly. A modern operating
system provides access to a number
of resources, which are available to
software running on the system, and
to external devices like networks via
the kernel. The operating system
must be capable of distinguishing
between requests which should be
allowed to be Processed, and others
which should not be processed. In
addition to allow or disallow model
of security system with a high level
of security also offers auditing
options.
Fig 7 : Data security system model

13. LINUX
Linux is one of popular version of UNIX operating System. It is open
source as its source code is freely available. It is free to use. Linux was
designed considering UNIX compatibility. It's functionality list is quite
similar to that of UNIX. Linux Operating System has primarily three
components:
 Kernel - Provides the required abstraction to hide low level hardware.
 System Utility - System
Utility programs are responsible to do
specialized, individual level tasks.
 System Library - libraries
implements most of the
functionalities of the
operating system.
Fig 8: Linux OS Components

14. The booting process in Linux is quite different than windows except the
BIOS and MBR features. There are some basic steps in Linux operating
system while booting. The first process starting when you turn on your
computer is BIOS ( Basic Input Output System).
LINUX BOOTING STEPS
FIG 9: LINUX Booting Steps

15. ANY QUESTION?????????
 THANK YOU………….