Define Operating System and explain how it acts as a Resource Manager.

 Q. Define Operating System and explain how it acts as a Resource Manager. 

Ans. Operating System: An operating system is an integrated set of specialised programs that are used to manage overall resources and operations of the computer. It is a specialised software that controls and monitors the execution of all the programs that reside in the computer. It is the interface between user and the computer.

A simple way of defining the operating system can be:

An operating system is a program that acts as an interface between the user and the computer hardware and controls and manages the overall resources of computer system.

O.S. as a Resource Manager in following ways:

1. Memory (Storage) Management 

(a) It keeps track of primary memory i.e. what part of it are im use by whom, what part are not in use etc.

(b) In multiprogramming it decides which process will get memory when and how much.

(c) Allocates the memory when the process or program request it to do so.

(d) Declaims (deallocate) the memory when the process no longer needs it or has been terminated. 

2. Processor Management

(a) Keep track of the processor and status of process.

(b) In multiprogramming it decides which process gets the processor & how much time. This function is called process scheduling.

(c) Allocate the processor (CPU) to a process.

(d) Deallocate processor when processor is no longer required.

3. Device Management 

(a) Keeps track of all devices.

(b) Decides which process gets the device when & for how much time.

(c) Allocate the device in the efficient way.

(d) Deallocate devices.

4. File Management 

(a) It keeps track of information, its location, uses, status etc. This collective facilities are often known as file system.

(b) Decides who get the resources.

(c) Allocates the resources.

(d) Deallocates the resources.

5. Security 

By means of passwords & similar techniques, preventing unauthorized access to programs & data.

6. Control over system performance 

Recording delays between request for a service & response from the system.

7. Job accounting

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

8. Interaction with the operators

The interaction takes place via the console of the computer in the form of the instructions from the operator acknowledging the same, action thereon, as well as informing the operation by means of a display screen of works & problem encountered.

9. Error -detecting aids

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

10. Coordination between other softwares and users

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