Operating Systems
Unit -1 Introduction to Operating System Concept
Name of the Topic: Introduction to Operating
System Concept
Lecture No 1
Dr A.NagaJyothi
Associate Professor
Applications
Why Study of Operating System
Tasks of Operating Systems
Main Goals of OS
– Execute user programs and makes
problems easier.
– Make the computer system convenient to
use.
– Computer Hardware usage in efficient
manner
Operating System Concepts
Course Contents
• Unit-I: Introduction to Operating System
Concept:
• Unit-II: Process Management
• Unit-III: Memory Management:
• Unit-IV: Concurrency:
• Unit-V: File system
CONTENTS
•
•
•
•
•
•
What is OS?
What OS does?
Structure of operating system
Operating Systems functions
Summary
Previous Questions
Computer
Hardware
Software
Applications
Computer
Hardware
Software
Applications
OPERATING SYSTEM
Computer
Hardware
Software
Applicati
ons
OPERATING SYSTEM
UNIX
Computer
Hardware
What is Operating Systems
What is OS?
• Operating System is a software, which makes a
computer to actually work.
• It is the software the enables all the programs we use.
• The OS organizes and controls the hardware.
• OS acts as an interface between the application
programs and the machine hardware.
• Examples: Windows, Linux, Unix and Mac OS, etc.,
KERNAL
KERNAL DEFINITION
A kernel is the core component of an
operating system. It is also a system
program. It is the part of Operating
System which coverts user command
into machine language.
Hardware
Kernel
Software
User
Applications
KERNAL
Vs
OPERATING SYSTEM
OPERATING SYSTEM
KERNEL
Operating System is a system
software.
Kernel is system software which is
part of operating system.
Operating System provides interface
b/w user and hardware.
kernel provides interface b/w
application and hardware.
It also provides protection and
security.
It’s main purpose is memory
management, disk management,
process management and task
management.
All system needs operating system
to run.
All operating system needs kernel to
run.
Type of operating system includes
single and multiuser OS,
multiprocessor OS, realtime OS,
Distributed OS.
Type of kernel includes Monolithic
and Micro kernel.
It is the first program to load when
computer boots up.
It is the first program to load when
operating system loads.
Three Elements of an OS
The Three Elements of an OS
• User Interface – The part of the OS that you
interface with.
• Kernel – The core of the OS. Interacts with the
Basic Input and Output System(BIOS) (at one
end), and the User Interface(UI) (at the other
end).
• File Management System – Organizes and
manages files.
Operating System Types
• Single User- One User works with the computer at that
time
• Multiuser – Two or more users work with the computer
at the same time
• Multitasking – Two or more processes running at the
same time.
• Multithreading – Two or more parts of the same
process running at the same time.
Different Operating Systems
UNIX
UNIX





Developed by Ken Thompson and Dennis Ritchie
Unix was launched in 1969
It is a
CLI (Command-Line Interface)
Written in the C programming language
Led to a variety of academic and commercial
variants, e.g. University of California, Berkeley
(BSD), Microsoft (Xenix), IBM (AIX) and Sun
Microsystems (Solaris)
LINUX
LINUX




Developed by Linus Benedict Torvalds
Linux was launched in 1992
Linux is a CLI (Command-Line Interface)
Torvalds made the code of Linux freely available to
everyone on the internet, and therefore lots of
people created their own versions of Linux, e.g.
Debian, RedHat, SUSE, SlackWare, Gentoo, Ubuntu
WINDOWS
WINDOWS





Developed by Microsoft - Bill Gates & Paul Allen
Windows was launched in 1985
Built on DOS (Disk Operating System), which is a
CLI (Command-Line Interface)
Has two modes User Mode (the user cannot directly
access the hardware) and Kernel Mode (the user
can access the hardware)
Runs on Computers, Tablets (Surface), and
integration with Xbox
APPLE MacOS(OS X)





Developed by Apple - Steve Wozniak & Steve Jobs
MacOS was launched in 1984
MacOS is a native GUI (Graphical User Interface)
MacOS evolved into OS X, which combined
technologies from MacOS, Unix, and NeXT
Runs on Computers and other devices.
ANDROID
ANDROID
Developed by Andy Rubin, Rich Miner, Nick Sears,
and Chris White
 Android was launched in 2003
 Based on the Linux kernel
 Android is a GUI designed primarily for
touchscreen mobile devices such as smartphones
and tablets

APPLE IOS
APPLE IOS




Developed by Steve Jobs and Scott Forstall
iOS was launched in 2007
Based on the MacOS
iOS is a GUI designed primarily for touchscreen
mobile devices such as iPhones, iPods, iPads, and
AppleTV.
PC Operating Systems
PC Operating Systems
• Microsoft Windows
• Mac OS
• Linux
Examples of Mobile OS
What OS does?
An operating system performs basic tasks such as,
• Controlling and allocating memory
• Prioritizing system requests
• Controlling input and output devices
• Facilitating networking
• Managing file systems.
STRUCTURE OF OPERATING SYSTEM Contd…
Structure of Operating System (Contd…):
The structure of OS consists of 4 layers:
1. Hardware
Hardware consists of CPU, Main memory, I/O
Devices, etc,
2. Software (Operating System)
Software includes process management routines,
memory management routines, I/O control routines,
file management routines.
3. System programs
This layer consists of compilers, Assemblers, linker
etc.
4. Application programs
This is dependent on users need. Ex. Railway
reservation system, Bank database management etc.,
Operating Systems functions
The main functions of operating systems are:
1.
2.
3.
4.
5.
6.
7.
Program creation
Program execution
Input/output operations
Error detection
Resource allocation
Accounting
protection
Computer-System Organization
• A modern general-purpose computer system
consists of one or more CPUs and a number of
device controllers connected through a
common bus that provides access between
components and shared memory.
• Each device controller is in charge of a specific
type of device (for example, a disk drive, audio
device, or graphics display).
PC Computer System
Outcomes
• Understand operating system (OS) as
a collection of software that manages
computer hardware resources and
provides common services for
computer programs.
Summary
• Operating system helps to make
computer hardware available to the
application
programs.
Without
Operating System we cannot access
computer hardware.
Previous Questions
1. What are the objectives and functions of
Operating system? Explain in detail?
2. What is the relationship between
operating
systems
and
computer
hardware.
Which Operating System Suits Your
Requirement ???
Quiz
1. What is operating system?
a) collection of programs that manages
hardware resources
b) system service provider to the application
programs
c) link to interface the hardware and
application programs
d) all of the mentioned
Thank You