By Vijay pal
Operating System Concepts
NOTES
Vijay pal
23
, UNIT – 1
Introduction to Operating System
An operating system is program that acts as an interface between the
user of the computer and computer hardware the main purpose of
operating system is to provide an environment in which the user can
execute its program in a convenient manner.
The operating system is the first program that is loaded into the
memory by a process called booting.
The operating system is the integrating set of programs that
manages the hardware resources like processor memory and
input/output devices.
The operating system is responsible for smooth operations of the
computer system most common operating system are: -
Windows, Linux, Mac etc.
Functions of operating system
I. Process Management: - The process management means the
assignment of processor to different task performed by the
computer system.
The Operating system performs following activities for
process management: -
a.) Creating and deleting both user and system process.
b.) Suspending and resuming process.
c.) Providing methods for process synchronization like: -
semaphores.
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, d.) Providing methods for handling deadlock.
II. Memory Management: - In multiprogramming environment
many programs are kept in the main memory to increase CPU
utilization.
When many programs reside in the main memory at the same
time memory management is important.
The operating system is responsible for following activities: -
a.) Keeping track that which part of memory are currently being
used by which process.
b.) Deciding which process is to be loaded in the memory when
memory space is free.
c.) Allocating and reallocating memory.
III. File Management: - File is the smallest representable information
in numeric, alphabetic or alpha numeric mode. These files are
grouped together to make directories.
The operating system performs following activities for file
management: -
a.) Creating and deleting files.
b.) Creating and deleting directories.
c.) Providing operations for files and directories like read, write,
modify, append etc.
d.) Backing up of files on a stable storage media.
IV. Input / Output Management: - It means the coordination and
assignment of different input / output devices to different
programs being executed.
The operating system performs following activities for input /
output management: -
a.) Issuing commands to different input / output devices.
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, b.) Capturing interrupt like hardware failure.
c.) Handling errors that occur in reading and writing process of
devices.
V. Protection and Security: - In multiprogramming environment
where many user processes reside in main memory at the same
time the protection methods control.
The excess of user’s program controls used by different
applications: -
a.) The operating system protects itself from user processes and
also different user process from one another.
b.) It provides protection to different resources like memory files
and CPU from unauthorized users.
c.) The computer security involves both internal and external
security.
External security means securing the system from
external factors like fire, floods, or leaking out of
information via a person.
Internal security deals with user authentication, access
control and cryptography.
Types of Operating System
1. Batch processing system
Batch processing is the oldest method for running program. The
computers in the past were very large in size and the input / output
devices were also different.
The users didn’t interact directly with computer system users
prepare the job on punched card and submit it to the computer
Page | 3
Operating System Concepts
NOTES
Vijay pal
23
, UNIT – 1
Introduction to Operating System
An operating system is program that acts as an interface between the
user of the computer and computer hardware the main purpose of
operating system is to provide an environment in which the user can
execute its program in a convenient manner.
The operating system is the first program that is loaded into the
memory by a process called booting.
The operating system is the integrating set of programs that
manages the hardware resources like processor memory and
input/output devices.
The operating system is responsible for smooth operations of the
computer system most common operating system are: -
Windows, Linux, Mac etc.
Functions of operating system
I. Process Management: - The process management means the
assignment of processor to different task performed by the
computer system.
The Operating system performs following activities for
process management: -
a.) Creating and deleting both user and system process.
b.) Suspending and resuming process.
c.) Providing methods for process synchronization like: -
semaphores.
Page | 1
, d.) Providing methods for handling deadlock.
II. Memory Management: - In multiprogramming environment
many programs are kept in the main memory to increase CPU
utilization.
When many programs reside in the main memory at the same
time memory management is important.
The operating system is responsible for following activities: -
a.) Keeping track that which part of memory are currently being
used by which process.
b.) Deciding which process is to be loaded in the memory when
memory space is free.
c.) Allocating and reallocating memory.
III. File Management: - File is the smallest representable information
in numeric, alphabetic or alpha numeric mode. These files are
grouped together to make directories.
The operating system performs following activities for file
management: -
a.) Creating and deleting files.
b.) Creating and deleting directories.
c.) Providing operations for files and directories like read, write,
modify, append etc.
d.) Backing up of files on a stable storage media.
IV. Input / Output Management: - It means the coordination and
assignment of different input / output devices to different
programs being executed.
The operating system performs following activities for input /
output management: -
a.) Issuing commands to different input / output devices.
Page | 2
, b.) Capturing interrupt like hardware failure.
c.) Handling errors that occur in reading and writing process of
devices.
V. Protection and Security: - In multiprogramming environment
where many user processes reside in main memory at the same
time the protection methods control.
The excess of user’s program controls used by different
applications: -
a.) The operating system protects itself from user processes and
also different user process from one another.
b.) It provides protection to different resources like memory files
and CPU from unauthorized users.
c.) The computer security involves both internal and external
security.
External security means securing the system from
external factors like fire, floods, or leaking out of
information via a person.
Internal security deals with user authentication, access
control and cryptography.
Types of Operating System
1. Batch processing system
Batch processing is the oldest method for running program. The
computers in the past were very large in size and the input / output
devices were also different.
The users didn’t interact directly with computer system users
prepare the job on punched card and submit it to the computer
Page | 3
