This document provides an overview of operating systems, including: - A brief history from early batch processing systems to modern graphical operating systems like Windows and MacOS. - The main functions of an operating system including memory management, process management, file management, and more. - Different types of operating systems such as batch, time-sharing, distributed, network, and real-time operating systems. - Operating system services, structures, system calls, and the system boot process.

1. Operating System
Unit –I
Prepared By
Prof. Amit Purohit
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2. Topics to be covered
• Introduction of Operating Systems
• History of Operating Systems
• Functions of Operating Systems
• Types of Operating Systems
• Operating System Services
• Operating System Structure
• System Calls and System Boots
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3. Introduction of Operating Systems
Software :- Software is a set of programs, which is designed to perform a
well-defined function. A program is a sequence of instructions written
to solve a particular problem.
There are two types of software −
• System Software- (OS, Compiler, Drivers etc.)
• Application Software-(Games, Ms Office , Media Player etc.)
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4. Introduction of Operating Systems
• An Operating system (OS) is a System software which acts as an
interface between the user and computer hardware.
• Every computer must have at least one OS to run other programs. An
application like Chrome, MS Word, Games, etc needs some
environment in which it will run and perform its task.
• Example: Windows OS, UNIX/LINUX OS, MAC OS, Android OS
etc.
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5. Computer system can be divided into four
components.
 User
System and application programs
Operating system
Hardware
Introduction to Operating Systems
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6. History of Operating Systems
The First Generation (1940's to early 1950's)
All programming was done in absolute machine language.
During this generation computers were generally used to solve
simple math calculations, operating systems were not
necessarily needed.
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7. History of Operating Systems
The Second Generation (1955-1965)
Operating systems in the 1950's were called single-stream
batch processing systems because the data was submitted in
groups
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8. History of Operating Systems
The Third Generation (1965-1980)
The third generation operating systems also introduced
multiprogramming.
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9. History of Operating Systems
The Fourth Generation (1980-Present Day)
Windows went on to become the largest operating system used
in technology today with releases of Windows 95, Windows 98,
Windows XP ,Windows 7 & Apple is the other major operating
system created in the 1980's.
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10. Operating System with Market Share
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11. Functions of OS
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12. Function of OS
• Memory management:- Memory management module
performs the task of allocation and de-allocation of memory
space to programs in need of this resources.
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13. Function of OS
• Process Management:- Process management helps OS to
create and delete processes. It also provides mechanisms for
synchronization and communication among processes.
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14. Function of OS
• File Management:- It manages all the file-related activities
such as organization storage, retrieval, naming, sharing, and
protection of files.
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15. Function of OS
• Device Management: Device management keeps tracks of all
devices. This module also responsible for this task is known as
the I/O controller. It also performs the task of allocation and de-
allocation of the devices.
• Security:- Security module protects the data and information of
a computer system against malware threat and authorized
access.
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16. Function of OS
• Networking: A distributed system is a group of processors
which do not share memory, hardware devices, or a clock. The
processors communicate with one another through the network.
• Job accounting: Keeping track of time & resource used by
various job and users.
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17. Types of operating Systems
Batch Operating System –
• In this type of system, there is no direct interaction between user and the
computer.
• The user has to submit a job (written on cards or tape) to a computer
operator.
• Then computer operator places a batch of several jobs on an input device.
• Jobs are batched together by type of languages and requirement.
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18. Time-Sharing Operating Systems
These systems are also known as Multitasking Systems. The task can
be from single user or from different users also. The time that each
task gets to execute is called quantum. After this time interval is
over OS switches over to next task.
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19. Distributed Operating System
Various autonomous interconnected computers communicate each other
using a shared communication network. Independent systems possess their
own memory unit and CPU. These are referred as loosely coupled
systems or distributed systems
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20. Network Operating System –
These systems run on a server and provide the capability to manage data,
users, groups, security, applications, and other networking functions. These
type of operating systems allow shared access of files, printers, security,
applications, and other networking functions over a small private network.
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21. Real-Time Operating System –
These types of OSs serves the real-time systems. The time
interval required to process and respond to inputs is very
small. This time interval is called response time.
Two types of Real-Time Operating System which are as
follows:
• Hard Real-Time Systems
• Soft Real-Time Systems
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22. Operating system services
• Program execution
• I/O operations
• File System manipulation
• Communication
• Error Detection
• Resource Allocation
• Protection
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23. Operating System structure
Simple Structure:-Such operating systems do not have well
defined structure and are small, simple and limited systems.
The interfaces and levels of functionality are not well
separated. MS-DOS is an example of such operating system.
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24. Layered structure: An OS can be broken into pieces and retain
much more control on system. In this structure the OS is
broken into number of layers (levels). The bottom layer (layer
0) is the hardware and the topmost layer (layer N) is the user
interface.
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25. System Calls and System Boots
• System Calls:- The interface between a process and
an operating system is provided by system calls
• There are many different system calls
– open()
– read()
– write()
– close()
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26. • System Boots:- Booting the system is done by
loading the Operating System into main
memory, and starting its execution.
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27. THANKS
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