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Operating system and it's functions

"An Operating System is an interface between the computer user and the computer hardware".

An operating system is an program that manages the computer hardware.Basically, a computer system can be divided roughly into four components the hardware the operating system the application programs and the users. It controls and coordinate the use of hardware among the various application programs for various users.
We have various operating systems available. Some popular operating system are: Linux, Unix, windows operating system which is mostly used these days, MAC operating system (specifically used by "apple").

Main Functions of Operating System:
1. Process management
2. Main Memory management
3. File management
4. Input/Output management
5. Secondary storage management

Process Management:
A program is a passive entity such as content of a file stored in disk, whereas a process is an active entity, with a program counter specifying the next instruction to execute. A process is a unit of work in a system.
The operating system is responsible for the following activities in connection with the process management:
  • Creating and deleting both user and system processes
  • Suspending and resuming the processes
  • Providing mechanism for process synchronism
  • Providing mechanism for deadlock handling and process communication
Main memory management: As we know the main memory is Central to the operation of a modern computer system. Main memory is a large array of words or bytes, ranging in size from hundreds of thousands to billions.
The operating system is responsible for the following activities in connection with memory management:
  • Keeping track of which parts of memory are currently being used and by whom.
  • deciding which processes are to be loaded into memory and when memory space is become available.
  • Allocating and deallocating memory space as needed.

File Management: A file is a collection of related information defined by its creator.
The operating system is responsible for the following activities in connection with the file management:
  • Creating and deleting files
  • Creating and deleting directories
  • Supporting primitives for manipulating files and directories
  • Mapping files onto secondary storage
  • Backing up files on stable storage media

Input/Output Management: One of the purposes of an operating system is to hide the peculiarities of specific hardware devices from the user. For example in Unix the peculiarities of input/output devices are hidden from the bulk of the operating system itself by the input/output subsystem.
The input/output subsystem consist of:
  • General device driver interface
  • Driver for specific hardware devices

Secondary storage management: The main purpose of a computer system is to execute programs. These programs with the data access must be in main memory or primary memory during execution. Because main memory is too small to accommodate all data and because the data that it holds are lost when power is lost so the computer system must provide to backup main memory.

So, the operating system is responsible for the following activities in connection with the disk management:
  • Free space management
  • Storage allocation
  • Disk scheduling

Also operating system provides services to programs and two uses of those programs, such as program execution. Error detection and resource allocation.

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