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.

Merits and limitations of computer

 1. (a) Discuss merits of computer.

(b) Discuss limitations of computer.

Ans.  (a) Merits of computer are as follow:
i) High Speed: A computer is a high speed device capable of performing arithmetic at unbelievable speed. The units of speed in computer are microsecond, the nanosecond and even the picosecond.

ii) Accuracy: Computers never commits errors in processing. Computerized systems sometimes do produce wrong results but in almost all such cases the error is because of wrong input of data and instructions.

iii) Reliability: (means strength) The reliability of computer is indeed very high. Computers are designed so as to make maintenance easy. Most of the hardware is in module form. When a component fails, the component can be replaced or repaired at a minimal cost.

iv) Versatility: (means having different skills & qualities) A computer is a very versatile machine. This machine can be used to solve the problems relating to various different fields. At one instant, it may be solving a complex scientific problem and the very next moment it may be playing a chess game and then a busy in taking up a payroll problem.

v) Automation: Once a program and instructions are input in the computers memory, the operator need not make intervention when program is being executed because the instructions automatically take care of the steps to be processed to solve the problem.

vi) Diligence: The capacity of computer of performing repetitive tasks without getting tired is called diligence. A computer can operate twenty four hours continuously without taking any rest. It works with same concentration and with same accuracy as the first instruction.

vii) Data Base: The use of computer facility in business organisation facilitates establishment of database. Data base integrates data records and reduces data redundancy (back ups ans duplicates).

viii) Reduction in Paper Work: The use of computers for data processing has reduced some of the paper needs through the storage of data in elaborately constructed data bases and files where they can retrieved (get back/ regain) when needed.

ix) Reduces Cost: Though the initial investment for installing a computer is high but it substantially reduces the cost of each of its transaction.

x) Facilitates Report Preparation: Data maintained with the help of a computer facilitates the preparation of various types of reports required by the organisational executives for the purpose of decision-making and control.

xi) Reduce the space requirements: The use of computers for office activities reduces the requirements of office space which otherwise is required.

xii) Reduce the manpower requirement:  The number of persons required for performing various organisational activities will be reduced by using a computer system.

xiii) Increased ability to perform computations: The use of computer has helped in performing computations with speed.

xiv) Intangible benefits: It includes customer image, leadership in the industry and community, increases customer morale and management confidence.

(b) Limitations of computers are as follow:
i) No I.Q.: It possesses (अधिकार) no intelligence of its own. It's I.Q. is zero atleast till today. It has to told what to do and in what sequence.

ii) The application logic must be understood: The computer can only process jobs which can be expressed in finite number of steps. Each step must be clearly defined. If the steps in the solution cannot be precisely stated, the job cannot be done.

iii) Dependent on human being.

iv) It requires a lot of looking after.

v) Environment: The environment for operating the computer should be suitable to it.

vi) No Feeling/Judgement: Computer cannot make judgement which a human being make in day to day life. Its judgement is based on the instructions given to it in the form of programmes that are written by us.

vii) It is very sensitive to dust particles even a small dust particle can make great losses to it.