BCA-3 rd Semester 030010304-Fundamentals Of Operating Systems Unit: 1 Introduction Short Answer Questions : 1. State two ways of process communication. 2. State any two uses of operating system according to user view. 3. List any four components of computer system. 4. Give any two differences between distributed operating system with real time operating system. 5. Give any two examples of mobile operating system. 6. Give a brief description of batch operating system. 7. Draw a diagram of memory layout for a multiprogramming system. 8. Name an operating system service that keep the track of users and resource utilization. 9. Which are the two operations performed in file system manipulation? 10. Give at least four services of operating system. 11. What is the importance of protection and security service of operating system? 12. How multiprogramming increases CPU utilization? 13. What does job pool consists? 14. Why CPU is never idle in multiprogramming system? 15. Differentiate between hard real time system and soft real time system. 16. Give at least one case where operating system is designed to maximize resource utilization. 17. What act as an intermediary between User and Hardware of Computer? Define it. Long Answer Questions : 1. Why we need Operating System? Explain it with reference to the responsibilities of Operating System. 2. Explain operating system structure in detail. 3. State any five classifications of operating system and explain any two of them. 4. Discuss any four services of operating system. 5. Describe components of computer system with the help of diagram. 6. Discuss the way in which operating system provides communication services. 7. Describe batch operating system and distributed operating system in detail. Ms. Anita Gianchandani Page 1
Select appropriate answer from the given options. 1. Operating System is responsible for A. Providing resources that are required by the user or applications B. Providing initial set-ups C. Services that is required for the communication over the network D. All of the above 2. Operating System ensures that all users get sufficient A. Processor time B. Throughput C. Turnaround time D. Response time 3. Which of the following operating system works on First Come First Served manner? A. Distributed Operating System B. Batch Operating System C. Time Sharing Operating System D. Multi programming Operating System 4. Which service of operating system keeps track of which users use how much and what kinds of computer resources? A. Program Execution B. I/O operations C. File-system manipulation D. Accounting 5. File system manipulation is responsible for A. Creating, deleting and naming files B. Detecting errors C. Allocating resources D. Executing programs 6. Which operating system allows many users to share the computer simultaneously A. Time-shared operating system B. personal operating system C. Batch Operating system D. Multiprogrammed operating system. 7. Operating System records the that leads to the error condition. A. Parallel events B. Event Handler C. Sequence Of events D. jobs in pool 8. Which of the following is the software layer nearest to the hardware? A.Operating System Ms. Anita Gianchandani Page 2
B. Application Program C. Compiler D. Loader 9. Operating System schedules the operations in order. A. Input, Data, Output B. Input, Output, Data C. Data, Input, Output D. Data, Output, Input Unit: 2 Process and Process Management Short Questions : 1. Give at least two differences between the following: a) Program and process. b) I/O bound process and CPU bound process. c) Job queue, Ready queue and Device queue. d) Long term and Short term Scheduler. 2. State one use of heap in the process when a process is loaded in memory. 3. In which state a process is when it is ready to be assigned to processor. 4. What is the need of program counter in Process Control Block? 5. State any three events that can occur after a CPU is allocated to the process. 6. Which information of process control block includes information about process priorities and pointers to scheduling queues? 7. Identify the task that includes switching the CPU to another process requires saving the state of the old process and loading the saved state for the new process. 8. Which two possibilities exist in terms of execution if a process creates a new process? 9. State at least two reasons why a parent terminates the execution of one of its children. 10. Name the phenomenon in which if a process terminates (either normally or abnormally), then all its children must also be terminated. Long Questions : 1. Discuss process control block with all its information. 2. Differentiate between long term scheduler and short term scheduler. 3. Explain context switch with the help of diagram. 4. Write a note on CPU-I/O burst cycle. 5. Describe scheduling criteria. 6. Compare and contrast FCFS and SJF scheduling algorithms. 7. Discuss process creation with possibilities of execution and address space. 8. Explain process states with the help of diagram. Ms. Anita Gianchandani Page 3
9. Explain the differences in the degree to which the following scheduling algorithms discriminate in favour of short processes: a. FCFS b. RR Practical Based Questions. 1. Assume you have the following five jobs to execute with one processor, with the jobs Arriving in the order listed in Table given below. Use FCFS, SJF and Priority non-pre-emptive scheduling algorithm. Process Burst Time Priority P1 10 2 P2 4 3 P3 8 1 P4 4 2 P5 6 6 a) Create a Gantt (timeline) chart illustrating the execution of these processes? b) What is the average turnaround time? c) What is the average waiting time? 2. Consider the following set of process, with the length of CPU burst time given in milliseconds: Process Burst Time Priority P1 4 3 P2 7 1 P3 16 2 P4 10 5 P5 3 4 The process are assumed to have arrived at time 0. Draw the Gantt chart illustrating the execution of these processes using FCFS, SJF, Priority scheduling (Small number implies higher priority), RR Scheduling (Time slice=2 ms). 3. Illustrate with an example the relationship between contexts switch and time slice. 4. Illustrate with an example how low priority processes suffer starvation. Select appropriate answer from the given options. 1. In Unix, Which system call creates the new process? A. fork B. create C. new 2. A process stack does not contain A. function parameters B. local variables C. return addresses D. PID of child process Ms. Anita Gianchandani Page 4
3. The address of the next instruction to be executed by the current process is provided by the A. CPU registers B. program counter C. process stack D. pipe 4. The processes that are residing in main memory and are ready and waiting to execute are kept on a list called A. job queue B. ready queue C. execution queue D. process queue 5. The interval from the time of submission of a process to the time of completion is termed as A. waiting time B. turnaround time C. response time D. throughput 6. Which scheduling algorithm allocates the CPU first to the process that requests the CPU first? A. first-come, first-served scheduling B. shortest job scheduling C. priority scheduling 7. In priority scheduling algorithm A. CPU is allocated to the process with highest priority B. CPU is allocated to the process with lowest priority C. equal priority processes cannot be scheduled 8. In priority scheduling algorithm, when a process arrives at the ready queue, its priority is compared with the priority of A. all process B. currently running process C. parent process D. init process 9. The number of processes completed per unit time is known as. A. Output B. Throughput C. Efficiency D. Capacity 10. The Process Control Block is : A. Process type variable B. Data Structure C. a secondary storage section Ms. Anita Gianchandani Page 5
D. a Block in memory 11. Which of the following do not belong to queues for processes? A. Job Queue B. PCB queue C. Device Queue D. Ready Queue 12. When the process issues an I/O request : A. It is placed in an I/O queue B. It is placed in a waiting queue C. It is placed in the ready queue D. It is placed in the Job queue 13. What is a long-term scheduler? A. It selects which process has to be brought into the ready queue B. It selects which process has to be executed next and allocates CPU C. It selects which process to remove from memory by swapping 14. The context of a process in the PCB of a process does not contain : A. the value of the CPU registers B. the process state C. memory-management information D. context switch time 15. Which of the following state transitions is not possible? A. blocked to running B. ready to running C. blocked to ready D. running to blocked 16. A parent process calling system call will be suspended until children processes terminate. A. wait B. fork C. exit D. exec 17. In UNIX, each process is identified by its : A. Process Control Block B. Device Queue C. Process Identifier 18. In UNIX, the return value for the fork system call is for the child process and for the parent process. A. A Negative integer, Zero B. Zero, A Negative integer C. Zero, A nonzero integer D. A nonzero integer, Zero 19. The child process can : (choose two) Ms. Anita Gianchandani Page 6
A. be a duplicate of the parent process B. never be a duplicate of the parent process C. have another program loaded into it D. never have another program loaded into it 20. The child process completes execution, but the parent keeps executing, then the child process is known as : A. Orphan B. Zombie C. Body D. Dead 21. The initial program that is run when the computer is powered up is called : A. boot program B. bootloader C. initializer D. bootstrap program 22. Which module gives control of the CPU to the process selected by the short-term scheduler? A. dispatcher B. interrupt C. scheduler 23. A process stack does not contain A. function parameters B. local variables C. return addresses D. PID of child process Unit: 3 Deadlocks Short Answer Questions. 1. List the sequence of utilization of resources by a process under the normal operation. 2. Which system calls are used for request and release of resources if the resources are as follows: a)device b)memory c)file 3. State the ways to determine a deadlock in the system. 4. Identify a condition for deadlock when There must exist a process that is holding at least one resource and is waiting to acquire additional resources that are currently being held by other processes. 5. What is the prevention technique used to ensure that circular wait does not hold? 6. State two side effects for preventing deadlock. 7. List three types of edges used in resource allocation graph. Ms. Anita Gianchandani Page 7
8. Give one example for each sharable and non-sharable resource. 9. A system has 2 disk drive, 5 printers and 8 scanners and a process needs 5 scanners, 3 printers and 1 disk drives. 10. What is no pre-emption condition for deadlock characterization? Long Answer Questions : 1. Discuss necessary condition for deadlock characterization. 2. Describe protocol used for preventing hold and wait condition. 3. Explain mutual exclusion and no pre-emption for deadlock prevention. 4. Discuss resource allocation graph for deadlock avoidance. 5. Give a real life example to explain no pre-emption technique prevention. 6. Discuss resource allocation sequence under the normal operation of system. 7. System calls are used for request and release of resources. Elaborate the statement. Practical/Scenario based questions. 1. Consider a system consisting of four resources of the same type that are shared by three processes, each of which needs at most two resources. Show that the system is deadlock free. 2. Consider a system consisting of m resources of the same type, being shared by n processes. Resources can be requested and released by processes only one at a time. Show that the system is deadlock-free if the following two conditions hold: a) The maximum need of each process is between 1 and m resources b) The sum of all maximum needs is less than m + n Select appropriate answer from the given options. 1. A set of processes is deadlock if A. each process is blocked and will remain so forever B. each process is terminated C. all processes are trying to kill each other 2. The circular wait condition can be prevented by A. defining a linear ordering of resource types B. using thread C. using pipes D. all of the mentioned 3. If the wait for graph contains a cycle : A. then a deadlock does not exist B. then a deadlock exists C. then the system is in a safe state D. either b or c 4. A computer system has 6 tape drives, with n processes competing for them. Each process may need 3 tape drives. The maximum value of n for which the system is guaranteed to be deadlock free is : A. 2 B. 3 C. 4 Ms. Anita Gianchandani Page 8
D. 1 5. A system has 3 processes sharing 4 resources. If each process needs a maximum of 2 units then, deadlock : A. can never occur B. may occur C. has to occur 6. The request and release of resources are. A. command line statements B. interrupts C. system calls D. special program 7. The number of resources requested by a process : A. must always be less than the total number of resources available in the system B. must always be equal to the total number of resources available in the system C. must not exceed the total number of resources available in the system D. must exceed the total number of resources available in the system 8. For Mutual exclusion to prevail in the system : A. at least one resource must be held in a non-sharable mode B. the processor must be a uniprocessor rather than a multiprocessor C. there must be at least one resource in a sharable mode D. All of these 9. For a Hold and wait condition to prevail : A. A process must be not be holding a resource, but waiting for one to be freed, and then request to acquire it B. A process must be holding at least one resource and waiting to acquire additional resources that are being held by other processes C. A process must hold at least one resource and not be waiting to acquire additional resources 10. Deadlock prevention is a set of methods : A. to ensure that at least one of the necessary conditions cannot hold B. to ensure that all of the necessary conditions do not hold C. to decide if the requested resources for a process have to be given or not D. to recover from a deadlock Unit: 4 Memory Management Short Answer Questions. 1. State at least one difference between compile time, load time and execution time binding. 2. What is instruction cycle? 3. Differentiate logical address space with physical address space. Ms. Anita Gianchandani Page 9
4. Which hardware device is responsible for mapping of virtual to physical address space? 5. What is roll in and roll out? 6. In swapping total transfer time is directly proportional to amount of memory swapped. What this statement states? 7. State the three common strategies used to select a free memory hole from the set of available memory hole. 8. What is internal and external fragmentation? 9. What are the two parts in which logical address is divided into? 10. What is the purpose of page table? 11. State at least two difference between page table and frame table. 12. What is Translation look aside buffer? 13. Why Translation look aside buffer must be erased? 14. What is TLB miss and TLB hit? 15. State the purpose of segmentation? 16. What each segment consist of? Long Answer Questions : 1. Discuss dynamic linking and dynamic loading. 2. What is the need of base and limit registers? 3. Describe dynamic relocation with relocation register. 4. Explain swapping with the help of diagram. 5. Discuss contiguous memory allocation with its disadvantages. 6. Describe basic method of paging with proper example. 7. Why paging and segmentation are required? Practical/Scenario based questions: Given memory partitions of 100K, 500K, 200K, 300K, and 600K (in order), how would each of the First-fit, Best-fit, and Worst-fit algorithms place processes of 212K, 417K, 112K, and 426K (in order)? Which algorithm makes the most efficient use of memory? Select appropriate answer from the given options. 1. CPU fetches the instruction from memory according to the value of A. program counter B. status register C. instruction register D. program status word 2. Which one of the following is the address generated by CPU? A. physical address B. absolute address C. logical address D. d) none of the mentioned 3. Run time mapping from virtual to physical address is done by A. memory management unit B. CPU C. PCI Ms. Anita Gianchandani Page 10
4. Memory management technique in which system stores and retrieves data from secondary storage for use in main memory is called A. fragmentation B. paging C. mapping 5. The address of a page table in memory is pointed by A. stack pointer B. page table base register C. page register D. program counter 6. Program always deals with A. logical address B. absolute address C. physical address D. relative address 7. The page table contains A. base address of each page in physical memory B. page offset C. page size D. d) none of the mentioned 8. What is compaction? A. a technique for overcoming internal fragmentation B. a paging technique C. a technique for overcoming external fragmentation D. a technique for overcoming fatal error 9. Operating System maintains the page table for A. each process B. each thread C. each instruction D. each address 10. In segmentation, each address is specified by : A. a segment number B. an offset C. a value D. a key 11. Each entry in a segment table has a : A. segment base B. segment peak C. segment limit D. segment value 12. The segment base contains the : A. starting logical address of the process Ms. Anita Gianchandani Page 11
B. starting physical address of the segment in memory C. segment length 13. The offset d of the logical address must be : A. greater than segment limit B. between 0 and segment limit C. between 0 and the segment number D. greater than the segment number 14. Physical memory is broken into fixed-sized blocks called. A. frames B. pages C. backing store 15. The size of a page is typically : A. varied B. power of 2 C. power of 4 16. Address Binding is : A. going to an address in memory B. locating an address with the help of another address C. binding two addresses together to form a new address in a different memory space D. a mapping from one address space to another 17. Binding of instructions and data to memory addresses can be done at : A. Compile time B. Load time C. Execution time D. All of these 18. Dynamic loading is : A. loading multiple routines dynamically B. loading a routine only when it is called C. loading multiple routines randomly Unit: 5 Virtual Memory Management Short Answer Questions 1. State at least one advantage of using virtual memory. 2. In which way virtual memory is implemented? 3. Give one use of demand segmentation. 4. What is page fault? 5. What happens if we increase the degree of multiprogramming in page replacement? 6. Which two major problems must be replaced to implement demand paging? Ms. Anita Gianchandani Page 12
7. Define: Belady s anamoly 8. Which two implementations are feasible in LRU Replacement algorithm? Long Answer Questions 1. When do page faults occur? Describe the actions taken by the operating system when a page fault occurs. 2. How virtual memory benefits to a system and user? 3. Discuss demand paging in detail. 4. Explain the need for Page Replacement. 5. Discuss the following algorithm in detail: a. First In First Out b. Optimal Page Replacement c. Least Recently Used Select appropriate answer from the given options. 1. Because of virtual memory, the memory can be shared among A. processes B. threads C. instructions 2. is the concept in which a process is copied into main memory from the secondary memory according to the requirement. A. Paging B. Demand paging C. Segmentation D. Swapping 3. Swap space exists in A. primary memory B. secondary memory C. CPU 4. When a program tries to access a page that is mapped in address space but not loaded in physical memory, then A. segmentation fault occurs B. fatal error occurs C. page fault occurs D. no error occurs 5. In FIFO page replacement algorithm, when a page must be replaced A. oldest page is chosen B. newest page is chosen C. random page is chosen 6. Which algorithm chooses the page that has not been used for the longest period of time whenever the page required to be replaced? A. first in first out algorithm Ms. Anita Gianchandani Page 13
B. additional reference bit algorithm C. least recently used algorithm D. counting based page replacement algorithm 7. Virtual memory allows : A. execution of a process that may not be completely in memory B. a program to be larger than the physical memory C. a program to be larger than the secondary storage D. execution of a process without being in physical memory 8. Virtual memory is normally implemented by. A. demand paging B. buses C. virtualization D. All of these 9. A page fault occurs when : A. a page gives inconsistent data B. a page cannot be accesses due to its absence from memory C. a page is invisible D. All of these 10. When a page fault occurs, the state of the interrupted process is : A. disrupted B. invalid C. saved 11. When a process begins execution with no pages in memory : A. process execution becomes impossible B. a page fault occurs for every page brought into memory C. process causes system crash 12. When the page fault rate is low : A. the turnaround time increases B. the effective access time increases C. the effective access time decreases D. a and b 13. Which of the following page replacement algorithms suffers from Belady s Anomaly? A. Optimal replacement B. LRU C. FIFO D. Both optimal replacement and FIFO 14. In question 2, if the number of page frames is increased to 4, then the number of page transfers : A. decreases B. increases C. remains the same Ms. Anita Gianchandani Page 14
15. A process refers to 5 pages, A, B, C, D, E in the order : A, B, C, D, A, B, E, A, B, C, D, E. If the page replacement algorithm is FIFO, the number of page transfers with an empty internal store of 3 frames is : A. 8 B. 10 C. 9 D. 7 16. A memory page containing a heavily used variable that was initialized very early and is in constant use is removed, then the page replacement algorithm used is : A. LRU B. LFU C. FIFO 17. A virtual memory system uses First In First Out (FIFO) page replacement policy and allocates a fixed number of frames to a process. Consider the following statements : P : Increasing the number of page frames allocated to a process sometimes increases the page fault rate Q : Some programs do not exhibit locality of reference Which of the following is TRUE? A. Both P and Q are true, and Q is the reason for P B. Both P and Q are true, but Q is not the reason for P C. P is false but Q is true D. Both P and Q are false 18. When a page is selected for replacement, and its modify bit is set : A. the page is clean B. the page has been modified since it was read in from the disk C. the page is dirty D. a and b 19. The aim of creating page replacement algorithms is to : A. replace pages faster B. increase the page fault rate C. decrease the page fault rate D. to allocate multiple pages to processes 20. A FIFO replacement algorithm associates with each page the A. time it was brought into memory B. size of the page in memory C. page after and before it D. All of these 21. Optimal page replacement algorithm is : A. Replace the page that has not been used for a long time B. Replace the page that has been used for a long time C. Replace the page that will not be used for a long time Ms. Anita Gianchandani Page 15
22. LRU page replacement algorithm associates with each page the A. time it was brought into memory B. the time of that page s last use C. page after and before it D. All of these 23. For 3 page frames, the following is the reference string : 7 0 1 2 0 3 0 4 2 3 0 3 2 1 2 0 1 7 0 1 How many page faults does the LRU page replacement algorithm produce? A. 10 B. 15 C. 11 D. 12 24. The two methods how LRU page replacement policy can be implemented in hardware are : (choose two) A. Counters B. RAM C. Stack D. Registers 25. When using counters to implement LRU, we replace the page with the : A. smallest time value B. largest time value C. greatest size D. None of the mentioned Ms. Anita Gianchandani Page 16