Tuesday, September 17, 2013

Operating System interview Questions and Answers-Set 1

Ques1- What is operating system?
Ans-An operating system is a system program that manages the computer hardware and provides a basis for application programs and acts as an intermediary between user of a computer and the computer hardware.

Ques2-What are the two main functions of an operating system?
Ans-The two main functions of an operating system are managing system resources and providing application programs with a set of primitives that provide higher-level services.

Ques3-What are the primary goals of an operating system?
Ans- 1.Convenience of user
     2.Efficient operation of computer system

Ques4-What does CPU do when there are no programs to run?
Ans-There is always a program to run(as long as computer is turned on.).The cycle of fetching ,decoding,and executing instructions neveer stops.When there are no user programs to run, the operating system will execute in a loop that does nothing(called a busy-wait loop or idle loop)until an interrupt occurs.

Ques5-What characteristic is common to traps,interrupts, supervisors calls and subroutine calls?
Ans-Traps,interrupts,supervisor  calls and subroutine calls all save the current value of the program counter and branch to a anew location in memory.

Ques6-What characteristic i common to traps,interrupts and supervisor calls, but different in subroutine calls?
Ans-Traps ,interrupts and supervisor calls cause the machine to shift into kernel mode.A subroutine call does not change the execution mode.

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