Operating System (OS)

Operating system is an essential component of the system software in a computer system. Its a program/set of programs that acts as intermediary between a user and computer hardware. OS can be found on almost all modern computing devices- from mobile phones to video game consoles to web servers to supercomputers. E.g.  MS DOS, UNIX, Windows 7, Windows 10, Ubuntu etc

Functions of an Operating System 

1. Boot up the computer
The process of starting or restarting a computer is known as booting. A cold boot is when you turn on a computer that has been turned off completely. A warm boot is the process when you restart the computer using OS i.e restart by Ctrl+Alt+Del or boot from sleep mode. 
2. Basic computer tasks
It performs basic tasks such as managing the peripheral devices. These days most OSs use support plug and play feature i.e a printer for example will be detected and configured automatically without any manual intervention. 
3. Provides a user interface
Two main types of UIs are: command line and GUI. With command line, user types commands on terminal to performs various tasks. With GUI, user interacts using a mouse, icons and menus. 
4. Handling of System Resources
OS handles system resources such as computer’s memory and sharing of CPU time by various applications or peripheral devices. It ensures each application gets necessary resources it needs to perform effectively. 
5. File management
OS handles the organization and tracking of files and directories. It keeps track of user’s activity as far as file creation, updation, deletion or movement is concerned. Two main types of file systems are:

  • File Allocation Table (FAT/FAT32) – It uses a file allocation table maintained by OS on a hard disk that provides a map of clusters (logical units of storage) that a file has been stored in. 
  • New Technology file system (NTFS) – File system introduced by Microsoft. It also allows permissions (read, write, execute) to be set for individual files and directories. 

 Types of Operating Systems 

1. Single user, single task OS
It is designed in a way that one user can effectively do one thing at a time. E.g. – Palm OS for palm handheld devices. 
2. Single user, multi tasking OS
It allows a single user run several programs at the same time. Personal computers/ Laptops are mostly used with this kind of OS. E.g – MS windows or Apple’s MacOs platforms. (You see you can write a blog and listen to music side by side when the downloading is on at back end- multi tasking!!!)3. Multi user OS
It allows many different users to take advantage of computer’s resources simultaneously. OS must allocate resources in a way that a problem with one user doesn’t affect the entire community of users. Main purpose is to maximize the resources. E.g. Mainframe systems.
4. Real time OS
It controls the environment as it has a data processing system. Time taken by system to respond to an input and display the result is called a response time. It uses an advanced algorithm for scheduling.5. Time sharing OS
It enables many people located at various terminals, to use the system, at a particular time. In other words, its a logical extension of multiprogramming. The main purpose is to minimize response time. 


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