Operating system

An operating system is a set of computer programs that manage hardware and software resources of a computer. The operating system forms a platform for other system software and for application software. An operating system performs basic tasks such as controlling and allocating memory, controlling input and output devices, managing file systems and prioritizing system requests.

Operating system is designed to manage system resources (Memory, Processor, input output devices, and information).  As a manager, operating system must do the following tasks,

·        Keep track of the resources

·        Enforce policies that determine who gets what, when and how much.

·        Allocating and reclaim the resource.

Process Management

A program in execution is known as process. A process needs several resources to accomplish its tasks. Process management deals with the assignment of resources, especially processor, to different tasks being performed by the computer system. We know that modern operating systems enable concurrent execution of many processes at a time by multitasking. In the case of single processor system, multitasking is done by switching process rapidly.  

The operating system is responsible for following function as a process manager,

·        Keep track of the processor and processes

·        Schedule processes

·        Allocate the processor to a process by setting up necessary registers. This module is called dispatcher.

·        Reclaim processor when process relinquishes processor usage, terminate or exceeds allowed amount of usage.

Some of the services provided by an operating system in this regard are:

·        Create and delete both system and user processes

·        Suspending and resuming processes

·        Change the priority of a process

·        Block a process

·        Process synchronization

·        Deadlock handling

·        Process communication

·        Block a process

·        Wake up a process and

·        Dispatch a process etc.

Memory Management

For a program to be executed, it must be mapped to absolute addresses and loaded into memory. Memory management deals with allocation of memory and other storage areas to system programs as well as the user programs and data. Managing virtual address space is another important functionality of the memory management unit.

The operating system is responsible for following activities in regarding with memory management,

·        Keep track of the memory, which parts of memory currently being used and by whom.

·        Decide which process get memory, when and how much.

·        Allocate the memory

·        Reclaim the memory when the process no longer needs it.

Device Management

It is the duty of device management unit to provide a uniform logical view of all devices connected to the system. Device management unit make use the functionalities of the device specific drivers to deal with them. The operating system is responsible for the following activities in connection with device management,

·        Keep track of devices

·        Decide the efficient way of device assignment.

·        Allocate devices to process

·        Reclaim the device

Information Management

Information management unit responsible for storing, retrieving, modifying and removing information on various devices. The operating system is responsible for following activities in connection with the information management:

·        Keep track of information, its location, use etc

·        Decide who gets the resources

·        Allocate the information. Eg: open a file

·        Deallocate the information. Eg: close a file

Some services provided  by OS in this regard are:

·        Create a file

·        Open a file

·        Read data from file

·        Write data to file

·        Close file

·        Create a directory

NEXT: Structure of an Operating System 

Index : Operating System