OPERATING
SYSTEMS
An
Operating System (OS) is software program that controls the internal activities
of the computer hardware and provides user interface. Application programs also
need to interact with the operating system for using hardware resources.
OS is the first program loaded
(copied) into the computer’s main memory after the computer is switched on.
An operating
system performs the following functions:
(1) Processor
Management: The operating system assigns processors (if a computer has more
than one processor) to the different tasks that must be performed by the
computer system.
(2) Memory Management: Operating system allocates the main
memory and secondary memory to the systems programs, user programs and data.
(3) Input/Output
Management: It
carrier out the input/output management and co-ordinates and assigns different
input and output devices.
(4) File Management: It manages files on various storage
devices and transfers these files from one storage device to another. It also
allows all files to be easily changed and modified through the use of text
editors or some other file manipulation software packages.
(5) Security
Management: It establishes data security and integrity. That is, it keeps
different programs and data in such a manner that they do not interfere each
other. Moreover, it also protects data from being destroyed by any other user.
(6) Interpretation of
command: For using
various system resources, a user communicates with the operating system via a
set of commands provided by it. Command interpretation module interprets user
commands and directs system resources to process the commands.
All
operating systems can be classified into four categories:
(1)Single
User Operating System: Operating
system which allows only one user to work on a computer at a time is known as
single user operating system. Examples include DOS, Windows, etc.
(2)Multiuser
Operating System: A
multiuser operating system allows a number of users to work together on a
single computer. Each user will be provided a terminal connected to a computer.
Examples include Linux, UNIX, Windows 2000, etc.
(3)
Single Tasking Operating System: Operating
system which can execute only a single task at a time is known as single tasking
operating system. Example- DOS.
