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Operating System Concept

The Operating System is a program with the following features:

• An operating system is a program that acts as an interface between the software and the computer hardware.

• It is an integrated set of specialized programs used to manage overall resources and operations of the computer.

• It is a specialized software that controls and monitors the execution of all other programs that reside in the computer, including application programs and other system software.

• A computer system has many resources (hardware and software), which may be require to complete a task.

• The commonly required resources are input/output devices, memory, file storage space, CPU etc.

• The operating system acts as a manager of the above resources and allocates them to specific programs and users, whenever necessary to perform a particular task. Therefore operating system is the resource manager i.e. it can manage the resource of a computer system internally.

• The resources are processor, memory, files, and I/O devices.

In simple terms, an operating system is the interface between the user and the machine.

Objectives of Operating System

The objectives of the operating system are:

1. To make the computer system convenient to use in an efficient manner.

2. To hide the details of the hardware resources from the users.

3. To provide users a convenient interface to use the computer system.

4. To act as an intermediary between the hardware and its users, making it easier for the users to access and use other resources.

5. To manage the resources of a computer system.

6. To keep track of who is using which resource, granting resource requests, and mediating conflicting requests from different programs and users.

7. To provide efficient and fair sharing of resources among users and programs.

Functions of Operating Systems

Memory Management

Keeps track of the primary memory, i.e. what part of it is in use by whom, what part is not in use, etc. and allocates the memory when a process or program requests it.

Processor Management

Allocates the processor (CPU) to a process and deallocates the processor when it is no longer required.

Device Management

Keeps track of all the devices. This is also called I/O controller that decides which process gets the device, when, and for how much time.

File Management

Allocates and de-allocates the resources and decides who gets the resources.

Security

Prevents unauthorized access to programs and data by means of passwords and other similar techniques.

Job Accounting

Keeps track of time and resources used by various jobs and/or users.

Control Over System Performance

Records delays between the request for a service and from the system.

Interaction with the Operators

Interaction may take place via the console of the computer in the form of instructions. The Operating System acknowledges the same, does the corresponding action, and informs the operation by a display screen.

Error-detecting Aids

Production of dumps, traces, error messages, and other debugging and error-detecting methods.

Coordination Between Other Software and Users

Coordination and assignment of compilers, interpreters, assemblers, and other software to the various users of the computer systems.