Operating System is an Important and core subject of Computer Science. All most in every competitive exam several questions are asked from this operating system in the Computer Awareness Section of the written exam. In this post I am presenting some basic objective questions from operating system.


1) Round robin scheduling is essentially the preemptive version of ________. 
1 FIFO 
2 Shortest job first 
3 Shortest remaining 
4 Longest time first 
Right Ans ) 1 

2) A page fault occurs 
1 when the page is not in the memory 
2 when the page is in the memory 
3 when the process enters the blocked state 
4 when the process is in the ready state 
Right Ans ) 1

3) Which of the following will determine your choice of systems software for your computer ? 
1 Is the applications software you want to use compatible with it ? 
2 Is it expensive ? 
3 Is it compatible with your hardware ? 
4 Both 1 and 3 
Right Ans ) 4 

4) Let S and Q be two semaphores initialized to 1, where P0 and P1 processes the following statements wait(S);wait(Q); ---; signal(S);signal(Q) and wait(Q); wait(S);---;signal(Q);signal(S); respectively. The above situation depicts a _________ . 
1 Semaphore 
2 Deadlock 
3 Signal 
4 Interrupt 
Right Ans ) 2 

5) What is a shell ? 
1 It is a hardware component 
2 It is a command interpreter 
3 It is a part in compiler 
4 It is a tool in CPU scheduling 
Right Ans ) 2 

6) Routine is not loaded until it is called. All routines are kept on disk in a relocatable load format. The main program is loaded into memory & is executed. This type of loading is called _________ 
1 Static loading 
2 Dynamic loading 
3 Dynamic linking 
4 Overlays 
Right Ans ) 3 

7) In the blocked state 
1 the processes waiting for I/O are found 
2 the process which is running is found 
3 the processes waiting for the processor are found 
4 none of the above 
Right Ans ) 1 

8) What is the memory from 1K - 640K called ? 
1 Extended Memory 
2 Normal Memory 
3 Low Memory 
4 Conventional Memory 
Right Ans ) 4 

9) Virtual memory is __________. 
1 An extremely large main memory 
2 An extremely large secondary memory 
3 An illusion of extremely large main memory 
4 A type of memory used in super computers. 
Right Ans ) 3 

10) The process related to process control, file management, device management, information about system and communication that is requested by any higher level language can be performed by __________. 
1 Editors 
2 Compilers 
3 System Call 
4 Caching 
Right Ans ) 3 

11) If the Disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98,37,14,124,65,67. 
1 310 
2 324 
3 315 
4 321 
Right Ans ) 4 

12) Multiprogramming systems ________. 
1 Are easier to develop than single programming systems 
2 Execute each job faster 
3 Execute more jobs in the same time 
4 Are used only on large main frame computers 
Right Ans ) 3 

13) Which is not the state of the process ? 
1 Blocked 
2 Running 
3 Ready 
4 Privileged 
Right Ans ) 4 

14) The solution to Critical Section Problem is : Mutual Exclusion, Progress and Bounded Waiting. 
1 The statement is false 
2 The statement is true. 
3 The statement is contradictory. 
4 None of the above 
Right Ans ) 2 

15) The problem of thrashing is effected scientifically by ________. 
1 Program structure 
2 Program size 
3 Primary storage size 
4 None of the above 
Right Ans ) 1 

16) The state of a process after it encounters an I/O instruction is __________. 
1 Ready 
2 Blocked/Waiting 
3 Idle 
4 Running 
Right Ans ) 2 

17) The number of processes completed per unit time is known as __________. 
1 Output 
2 Throughput 
3 Efficiency 
4 Capacity 
Right Ans ) 2 

18) _________ is the situation in which a process is waiting on another process,which is also waiting on another process ... which is waiting on the first process. None of the processes involved in this circular wait are making progress. 
1 Deadlock 
2 Starvation 
3 Dormant 
4 None of the above 
Right Ans ) 1 

19) Which of the following file name extension suggests that the file is Backup copy of another file ? 
1 TXT 
2 COM 
3 BAS 
4 BAK 
Right Ans ) 4 

20) Which technique was introduced because a single job could not keep both the CPU and the I/O devices busy? 
1 Time-sharing 
2 SPOOLing 
3 Preemptive scheduling 
4 Multiprogramming 
Right Ans ) 4 

21) A critical region 
1 is a piece of code which only one process executes at a time 
2 is a region prone to deadlock 
3 is a piece of code which only a finite number of processes execute 
4 is found only in Windows NT operation system 
Right Ans ) 1 

22) The mechanism that bring a page into memory only when it is needed is called _____________ 
1 Segmentation 
2 Fragmentation 
3 Demand Paging 
4 Page Replacement 
Right Ans ) 3 

23) PCB = 
1 Program Control Block 
2 Process Control Block 
3 Process Communication Block 
4 None of the above 
Right Ans ) 2 

24) FIFO scheduling is ________. 
1 Preemptive Scheduling 
2 Non Preemptive Scheduling 
3 Deadline Scheduling 
4 Fair share scheduling 
Right Ans ) 2 

25) Switching the CPU to another Process requires to save state of the old process and loading new process state is called as __________. 
1 Process Blocking 
2 Context Switch 
3 Time Sharing 
4 None of the above 
Right Ans ) 2 

26) Which directory implementation is used in most Operating System? 
1 Single level directory structure 
2 Two level directory structure 
3 Tree directory structure 
4 Acyclic directory structure 
Right Ans ) 3 

27) The Banker¿s algorithm is used 
1 to prevent deadlock in operating systems 
2 to detect deadlock in operating systems 
3 to rectify a deadlocked state 
4 none of the above 
Right Ans ) 1 

28) A thread 
1 is a lightweight process where the context switching is low 
2 is a lightweight process where the context swithching is high 
3 is used to speed up paging 
4 none of the above 
Right Ans ) 1 

29) ______ is a high level abstraction over Semaphore. 
1 Shared memory 
2 Message passing 
3 Monitor 
4 Mutual exclusion 
Right Ans ) 3 

30) A tree sturctured file directory system 
1 allows easy storage and retrieval of file names 
2 is a much debated unecessary feature 
3 is not essential when we have millions of files 
4 none of the above 
Right Ans ) 1




Second Part

1) Routine is not loaded until it is called. All routines are kept on disk in a relocatable load format. The main program is loaded into memory & is executed. This type of loading is called _________ 
1 Static loading 
2 Dynamic loading 
3 Dynamic linking 
4 Overlays 
Ans ) 3 

2) Which of the following is crucial time while accessing data on the disk? 
1 Seek time 
2 Rotational time 
3 Transmission time 
4 Waiting time 
Ans ) 1 

3) The host repeatedly checks if the controller is busy until it is not. It is in a loop that status register's busy bit becomes clear. This is called _____________ and a mechanism for the hardware controller to notify the CPU that it is ready is called ___________. 
1 Interrupt and Polling 
2 Polling and Spooling 
3 Polling and Interrupt 
4 Deadlock and Starvation 
Ans ) 3 

4) Unix Operating System is an __________. 
1 Time Sharing Operating System 
2 Multi-User Operating System 
3 Multi-tasking Operating System 
4 All the Above 
Ans ) 4 

5) Which of the following memory allocation scheme suffers from External fragmentation? 
1 Segmentation 
2 Pure demand paging 
3 Swapping 
4 Paging 
Ans ) 1 

6) Information about a process is maintained in a _________. 
1 Stack 
2 Translation Lookaside Buffer 
3 Process Control Block 
4 Program Control Block 
Ans ) 3 

7) Distributed OS works on the ________ principle. 
1 File Foundation 
2 Single system image 
3 Multi system image 
4 Networking image 
Ans ) 2 

8) The problem of fragmentation arises in ________. 
1 Static storage allocation 
2 Stack allocation storage 
3 Stack allocation with dynamic binding 
4 Heap allocation 
Ans ) 4 

9) Which file system does DOS typically use ? 
1 FAT16 
2 FAT32 
3 NTFS 
4 WNFS 
Ans ) 1 

10) The program is known as _________ which interacts with the inner part of called kernel. 
1 Compiler 
2 Device Driver 
3 Protocol 
4 Shell 
Ans ) 4 

11) The time taken by the disk arm to locate the specific address of a sector for getting information is called __________. 
1 Rotational Latency 
2 Seek Time 
3 Search Time 
4 Response Time 
Ans ) 2 

12) Which file system does Windows 95 typically use ? 
1 FAT16 
2 FAT32 
3 NTFS 
4 LMFS 
Ans ) 2 

13) Identify the odd thing in the services of operating system. 
1 Accounting 
2 Protection 
3 Error detection and correction 
4 Dead lock handling 
Ans ) 3 

14) Cryptography technique is used in ________. 
1 Polling 
2 Job Scheduling 
3 Protection 
4 File Management 
Ans ) 3 

15) Which of the following is not advantage of multiprogramming? 
1 Increased throughput 
2 Shorter response time 
3 Decreased operating system overhead 
4 Ability to assign priorities to jobs 
Ans ) 3 

16) In ______ OS, the response time is very critical. 
1 Multitasking 
2 Batch 
3 Online 
4 Real-time 
Ans ) 4 

17) An optimal scheduling algorithm in terms of minimizing the average waiting time of a given set of processes is ________. 
1 FCFS scheduling algorithm 
2 Round robin scheduling algorithm 
3 Shorest job - first scheduling algorithm 
4 None of the above 
Ans ) 3 

18) Real time systems are ________. 
1 Primarily used on mainframe computers 
2 Used for monitoring events as they occur 
3 Used for program development 
4 Used for real time interactive users 
Ans ) 2 

19) Which technique was introduced because a single job could not keep both the CPU and the I/O devices busy? 
1 Time-sharing 
2 SPOOLing 
3 Preemptive scheduling 
4 Multiprogramming 
Ans ) 4 

20) Inter process communication can be done through __________. 
1 Mails 
2 Messages 
3 System calls 
4 Traps 
Ans ) 2 

21) In Priority Scheduling a priority number (integer) is associated with each process. The CPU is allocated to the process with the highest priority (smallest integer = highest priority). The problem of, Starvation ? low priority processes may never execute, is resolved by __________. 
1 Terminating the process. 
2 Aging 
3 Mutual Exclusion 
4 Semaphore 
Ans ) 2 

22) CPU performance is measured through ________. 
1 Throughput 
2 MHz 
3 Flaps 
4 None of the above 
Ans ) 1 

23) PCB = 
1 Program Control Block 
2 Process Control Block 
3 Process Communication Block 
4 None of the above 
Ans ) 2 

24) Software is a program that directs the overall operation of the computer, facilitates its use and interacts with the user. What are the different types of this software ? 
1 Operating system 
2 Language Compiler 
3 Utilities 
4 All of the above 
Ans ) 4 

25) A __________ is a software that manages the time of a microprocessor to ensure that all time critical events are processed as efficiently as possible. This software allows the system activities to be divided into multiple independent elements called tasks. 
1 Kernel 
2 Shell 
3 Processor 
4 Device Driver 
Ans ) 1 

26) The primary job of the operating system of a computer is to ________. 
1 Command Resources 
2 Manage Resources 
3 Provide Utilities 
4 Be user friendly 
Ans ) 2 

27) With the round robin CPU scheduling in a time-shared system ________. 
1 Using very large time slice degenerates in to first come first served algorithm 
2 Using extremely small time slices improve performance 
3 Using extremely small time slices degenerate in to last in first out algorithm 
4 Using medium sized time slices leads to shortest request time first algorithm 
Ans ) 1 

28) Which of the following is a criterion to evaluate a scheduling algorithm? 
1 CPU Utilization: Keep CPU utilization as high as possible. 
2 Throughput: number of processes completed per unit time. 
3 Waiting Time: Amount of time spent ready to run but not running. 
4 All of the above 
Ans ) 4 

29) Which of the following is contained in Process Control Block (PCB)?
1 Process Number 
2 List of Open files 
3 Memory Limits 
4 All of the Above 
Ans ) 4 

30) Super computers typically employ _______. 
1 Real time Operating system 
2 Multiprocessors OS 
3 desktop OS 
4 None of the above 
Ans ) 2