Operating system - objectives and functions

1. B.Abinaya bharathi
I-M.Sc[Cs&IT]
Nadar Saraswathi college of Arts and Science,
Theni

2. * An operating system is a program that acts as an
interface between the user and the computer hardware and
controls the execution of all kinds of programs.
* OS is a layer of software whose job is to manage all
devices and provide user programs with a simpler interface to
the hardware.

3. Objectives of OS
* Convenience
* Efficiency
* Ability to evolve
Convenience: OS makes a computer more convenient to use.
Efficiency: OS allows the computer system resources to be used
in an efficient manner.
Ability to evolve: OS should be constructed in such a way as to
permit the effective development, testing, and introduction of
new system functions without interfering with service.

4. Functions of OS
* Program development
* Program execution
* Access to I/O devices
* System access
* Controlled access to files
* Error detection and response
* Accounting

5. Functions of OS

6. Program development
* OS provides a variety of facilities and services, such as
editors and debuggers, to assist the programmer in creating
programs
Program execution
* To execute a program first we need to load the data,
* Needed devices are initialized .OS handle all these
scheduling duties.
Access to I/O devices
* Each I/O devices use some set of instruction for
operation ,OS provide a uniform interface that provides the
user to acess the I/O device.

7. Controlled access to files
* OS must reflect a detailed understanding of structure
of the data contained in the files on the storage medium
. * OS provide a protection mechanisms to control access
to the files.
System access
* In a public system ,the OS control the access to a
system.
* OS protect the data and resource from unauthorized
users.
Error detection and response
* Error may occur while system running like device
failure , software error, etc,.
* OS must clears that error condition.

8. OS as a user /computer interface
* user view of the computer refers to the interface being
used
* The goal of the Operating System is to maximize the
work and minimize the effort of the user.
* Most of the systems are designed to be operated by
single user, however in some systems multiple users can share
resources, memory.
* In these cases Operating System is designed to handle
available resources among multiple users and CPU efficiently.
* Operating System must be designed by taking both
usability and efficient resource utilization into view.

9. OS as a user /computer interface

10. OS as a Resource manager
* Operating System is allocator, which allocate
memory, resources among various processes.It controls the
sharing of resources among programs.
* It prevents improper usage, error and handle
deadlock conditions.
* It is a program that runs all the time in the system in
the form of Kernel.
* It controls application programs that are not part of
Kernel.
* It mamages the resources efficiently.

11. OS as a Resource manager

12. THANK YOU