operating system,basics,functions,functions of operating system,types of operating system,OS basics

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What is an Operating System?
An operating system is the most important software that runs on a computer. It manages
the computer's memory, processes, and all of its software and hardware. It acts as an
interface between the hardware, application programs, files and the user. It also allows
you to communicate with the computer without knowing how to speak the computer's
"language." Without an operating system, a computer is useless. A computer without an
operating system is just like a body without soul.
Functions of Operating system
 Process Management
 Memory Management
 File Management
 Security management
 Command Interpreter
1. Process management
 By process management OS manages many kinds of activities:-
 All process from start to shut down.
 Creation and deletion of user and system processes.
2. Memory Management
 The major activities of an operating regard to memory-management are:-
 Decide which process are loaded into memory when memory space
becomes available.
 Allocate and deallocate memory space as needed.
3. File Management
 The file management system allows the user to perform such tasks:-
 Creating files and directories
 Renaming files

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 Copying and moving files
 Deleting files
4. Security Management
 By security management OS manages many tasks such as:-
 Alert messages
 Dialogue boxes
 Firewall
 Passwords
5. Command Interpreter
 A command interpreter is an interface between the system and the user.
There are two types of user interface:-
 Command line
 Graphical user interface
 With a command line user interface the user interact with the OS by typing
commands to perform specific tasks.
 With a graphical user interface the user interacts with the OS by using a mouse
to access windows icons and menus.
Types of operating system:
Real-Time OS:
The operating system developed to perform real-time application process data as it comes
in, typically without buffering delays. Processing time requirements (including
any OS delay) are measured in tenths of seconds or shorter.They are used to run
computers embedded in machinery, robots, scientific instruments and industrial systems
Typically, it has little user interaction capability, and no end-user utilities.
Examples: Wind River, Real-time Linux, Real-time Windows NT.
Single-user, single task:
Operating systems, designed to manage the computer so that one user can effectively do
one thing at a time.
The Palm OS used in many palmtop computers (PDA’s) is an example of a single -user,

3. Single-task OS
Single-User, multitasking:
Most popular OS
Used by most all PC’s and Laptops
Examples: Windows, Mac OS.
Lets a single user interact with several programs, simultaneously.
Multi-user:
A multi-user OS allows many users to take advantage of the computer's resources
simultaneously.
The OS must make sure that the requirements of the various users are balanced, and that
the programs they are using each have sufficient and separate resources so that a problem
with one user doesn't affect any of the other users.
Examples: Linux, Unix.
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