Short  Question Answers

  Q What is the main purposes of an operating system ?

  A  The main purpose of an operating system is to :-

• To provide an environment for a computer user to execute  on computer hardware in a convenient and efficient manner.
• To allocate the separate resources of the computer as needed to solve the problem given. The allocation process should be as fair and efficient as possible.

Q What is the purpose of system calls ?

A System calls allow user-level processes to request services of the operating system.

  Q What are the three major activities of an operating system in regard to memory management ?

A   Activities of opearting system with regard to memory management are-

a. Keep track of which parts of memory are currently being used and by whom.

b. Decide which processes are to be loaded into memory when memory space becomes available.

c. Allocate and deallocate memory space as needed.

Q What are the major activities of an operating system in regard to secondary-storage management?

A The major activities are  :- 

• Free-space management.
• Storage allocation.
• Disk scheduling.

  Q What is the purpose of the command interpreter? Why is it usually separate from the kernel?

A It reads commands from the user or from a file of commands and executes them, usually by turning them into one or more system calls. It is usually not part of the kernel since the command interpreter is subject to changes.

 

Q What system calls have to be executed by a command interpreter or shell in order to start a new process?

A In Unix systems, a fork system call followed by an exec system call need to be performed to start a new process. The fork call clones the currently executing process, while the exec call overlays a new process based on a different executable over the calling process.

 

Q What is the purpose of system programs ?

A: System programs can be thought of as bundles of useful system calls. They provide basic functionality to users so that users do not need to write their own programs to solve common problems.
  Q What is the purpose of system calls ?

A: System calls allow user-level processes to request services of the operating system.
 

Q  When a process creates a new process using the fork() operation, which of the following state is shared between the parent process and the child process?

a. Stack

b. Heap

c. Shared memory segments

A:Only the shared memory segments are shared between the parent process and the newly forked child process. Copies of the stack and the heap are made for the newly created process.