Maharashtra State Board of Technical Education Mumbai

Program Name
Computer Engineering

Course Name
Operating System(OSY-22516)

Unit-I
Overview of Operating System

Subtopic 1.1- Operating System-Concept

B P Bhagat
Lecturer in Computer Engineering
Government Polytechnic Yavatmal
Course Outcomes
After Completion of Operating System (OSY) course, students will able to:

a. Install Operating System and configure it.

b. Use Operating System tools to perform various functions
c. Execute process commands for performing process,
management operations
d. Apply scheduling algorithms to calculate turnaround time
and average waiting time
e. Calculate efficiency of different memory management
techniques
f. Apply File management techniques

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Contents and Learning Outcome
• Operating System Concepts
• Components of Operating System
• Operations of OS:
-Program management
-Resource management
-Security and Protection
• Views of OS: User View and System view

Learning Outcome(LO 1b)

Explain characteristic of the given types of Operating System

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 Operating System - Concept
• Definition: Operating System (OS) is a program that acts as an
intermediary between a user of a computer and the computer
hardware.
• It controls the execution of application program.
• It manages the computer’s hardware.

Purpose of Operating System

To provide an environment in
which a user can execute
programs in a convenient and
efficient manner.
Abstract view of Computer System
A computer system can be divided into four parts:

• 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
(compilers, database systems, video games,
business programs).

• Users (people, machines, other computers).

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Operating System Components

Process Main Memory

File Management
Management Management

I/O System Secondary Storage

Management Management

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 Operating System Components
• Process Management
– OS is responsible for activities in connection to process and
thread Management.
– Creation and deletion of user and system processes.
– Scheduling of processes.
• Main-Memory Management
– OS is responsible for activities related to main memory.
– Allocation and De-allocation techniques.
– Keeping track of the status of each location.
– Determine allocation policy.
– Several memory scheme exist to improve both utilization of CPU
and speed up response to users.

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Operating System Components

• File management
– Computer store information on different types of physical
media.
– Each of these media has its own characteristics and physical
organization.
– OS is responsible for activities related to File management.
– creating and deleting the files and directories.
– Mapping or Backing up files onto secondary storage devices.
– Transmission between main memory to secondary storage.

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Operating System Components
• I/O System (Device) Management
– OS is responsible for activities related to I/O sytem.
– I/O subsystem manages devices, transfer data and detects
I/O completion and driver for each specific hardware device.
– A memory management components that includes buffering,
caching and spooling.

• Secondary Storage Management

– Main memory is too small to accommodate all data and
programs permanently, hence computer system provides
secondary storage to backup main memory.
– Key goal of OS is to provide interface to rest of system and to
optimize I/O for maximum concurrency.

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Operations of Operating System
• Program Management
– It provides control access to shared resources.
– Control execution of user applications.
– Creation, execution and deletion of processes.
– Resuming or Scheduling process
• Resource Management
– Resources: CPU, Memory (RAM), file-storage space, I/O , files, printers etc.
– OS works as resource allocator.
– Use CPU scheduling algorithm for better CPU utilization.
• Protection and Security
– If a computer system has multiple users and processes executing, then access to
data must be regulated.
– Thus Protection is mechanism for controlling the access of processes or users to
the resources, defined by a computer system.
– The job of security is to defend a system from external and internal attacks such
as viruses, worms, denial-of-service attacks, identify theft and theft of service.
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 Views of OS: User View
• Computer users sit in front of a PC, consisting of monitor, K/B, mouse and system
unit.
– The goal is to maximize the work that user is performing.
– OS is designed to give ease of use with some attention to performance and none
to resource utilization.
• User sit at a terminal connected to mainframe or minicomputer. Other users
accessing the same computer through other terminals.
– Users share resources and may exchange information.
– OS is designed to maximize resource utilization efficiently (CPU, memory & I/O)
• User sit at workstations connected to network of other workstation and servers.
– Users have dedicated resources at their disposal but share resources as
networking and servers-(file, compute and print servers)
– OS is designed to compromise between individual usability and Resource
utilization.
• Some computers have little or no user view.
For example – Embedded computers in Home devices and Automobiles.
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Views of OS: System View
From computer‘s point of view OS is the program involved with the
hardware.
• Resource allocator
OS act as a Resource Manager and decide how to allocates
resources to solve the problems.
Multiple users get all computing resources simultaneously.
– CPU time
– Memory (RAM)
– File system (storage space)
– I/O devices (display, printers, keyboard,mouse,etc..)
• Control program – Manages the execution of user programs and
prevent errors and improper use of computer.
• Controls operations of I/O devices.
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Contents Covered…
In this session, following topics are covered:

OVERVIEW OF OPERATING SYSTEM

 Operating System Concepts
 Components of Operating System
 Operations of OS:
Program management
Resource management
Security and Protection
 Views of OS: User View and System view

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Reference :

Operating System Concept

by Abraham Silberchaz,Peter Galvin,Greg Gagne

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