2. The table contains the base address of each page in physical memory.
Correct : C. page
3. The size of a page is typically
Correct : B. power of 2
4. If the size of logical address space is 2 to the power of m, and a page size is 2 to the power of n addressing units, then the high order bits of a logical address designate the page number, and the low order bits designate the page offset.
Correct : D. m – n, n
5. The operating system maintains a table that keeps track of how many frames have been allocated, how many are there, and how many are available.
Correct : C. frame
6. Paging increases the time.
Correct : C. context – switch
7. Smaller page tables are implemented as a set of
Correct : D. registers
8. The page table registers should be built with
Correct : B. very high speed logic
9. For larger page tables, they are kept in main memory and a points to the page table.
Correct : A. page table base register
10. For every process there is a
Correct : A. page table
11. Time taken in memory access through PTBR is
Correct : D. slowed by a factor of 2
12. Each entry in a translation lookaside buffer (TLB) consists of
Correct : A. key
13. If a page number is not found in the TLB, then it is known as a
Correct : A. tlb miss
14. An uniquely identifies processes and is used to provide address space protection for that process.
Correct : B. address space identifier
15. The percentage of times a page number is found in the TLB is known as
Correct : B. hit ratio
16. Memory protection in a paged environment is accomplished by
Correct : D. protection bit with each page
17. When the valid – invalid bit is set to valid, it means that the associated page
Correct : C. is in the process’s logical address space
18. When there is a large logical address space, the best way of paging would be
Correct : B. a two level paging algorithm
19. is the concept in which a process is copied into the main memory from the secondary memory according to the requirement.
Correct : B. demand paging
20. The pager concerns with the
Correct : D. user programs can implement dynamic loading without any special support from hardware or operating system
21. In paged memory systems, if the page size is increased, then the internal fragmentation generally
Correct : B. becomes more
22. Swap space exists in
Correct : B. secondary memory
23. When a program tries to access a page that is mapped in address space but not loaded in physical memory, then
Correct : C. page fault occurs
24. Effective access time is directly proportional to
Correct : A. page-fault rate
25. In FIFO page replacement algorithm, when a page must be replaced
Correct : A. oldest page is chosen
26. Virtual memory allows
Correct : A. execution of a process that may not be completely in memory
27. A process is thrashing if
Correct : A. it is spending more time paging than executing
28. The ability to execute a program that is only partially in memory has benefits like
Correct : D. all of the mentioned
29. Virtual memory is normally implemented by
Correct : A. demand paging
30. Segment replacement algorithms are more complex than page replacement algorithms because
Correct : C. segments have variable sizes
31. A swapper manipulates whereas the pager is concerned with individual of a process.
Correct : C. the entire process, pages
32. Using a pager
Correct : C. decreases the swap time & amount of physical memory needed
33. The valid – invalid bit, in this case, when valid indicates?
Correct : C. the page is in memory
34. A page fault occurs when?
Correct : B. a page cannot be accessed due to its absence from memory
35. When a page fault occurs, the state of the interrupted process is
Correct : C. saved
36. When a process begins execution with no pages in memory?
Correct : B. a page fault occurs for every page brought into memory
37. If the memory access time is denoted by ‘ma’ and ‘p’ is the probability of a page fault (0 <= p <= 1). Then the effective access time for a demand paged memory is
Correct : C. (1-p) x ma + p x page fault time
38. When the page fault rate is low
Correct : C. the effective access time decreases
39. Locality of reference implies that the page reference being made by a process
Correct : B. is likely to be one of the pages used in the last few page references
40. Which of the following page replacement algorithms suffers from Belady’s Anomaly?
Correct : C. fifo
41. In question 2, if the number of page frames is increased to 4, then the number of page transfers
Correct : B. increases
42. 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
Correct : C. fifo
43. Users that their processes are running on a paged system.
Correct : B. are unaware
44. If no frames are free, page transfer(s) is/are required.
Correct : B. two
45. A FIFO replacement algorithm associates with each page the
Correct : A. time it was brought into memory
46. What is the Optimal page – replacement algorithm?
Correct : C. replace the page that will not be used for a long time
47. LRU page – replacement algorithm associates with each page the
Correct : B. the time of that page’s last use
48. What are the two methods of the LRU page replacement policy that can be implemented in hardware?
Correct : C. stack & counters
49. When using counters to implement LRU, we replace the page with the
Correct : A. smallest time value
50. There is a set of page replacement algorithms that can never exhibit Belady’s Anomaly, called
Correct : B. stack algorithms
51. The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by
Correct : A. the instruction set architecture
52. What is the reason for using the LFU page replacement algorithm?
Correct : A. an actively used page should have a large reference count
53. In segmentation, each address is specified by
Correct : A. a segment number & offset
54. Each entry in a segment table has a
Correct : A. segment base
55. The segment limit contains the
Correct : C. segment length
56. The offset ‘d’ of the logical address must be
Correct : B. between 0 and segment limit
57. If the offset is legal
Correct : A. it is used as a physical memory address itself
58. When the entries in the segment tables of two different processes point to the same physical location
Correct : C. segments are shared
59. The protection bit is 0/1 based on
Correct : C. read – write
60. If there are 32 segments, each of size 1Kb, then the logical address should have
Correct : A. 13 bits
61. Consider a computer with 8 Mbytes of main memory and a 128K cache. The cache block size is 4 K. It uses a direct mapping scheme for cache management. How many different main memory blocks can map onto a given physical cache block?
Correct : C. 64
62. A multilevel page table is preferred in comparison to a single level page table for translating virtual address to physical address because
Correct : B. it helps to reduce the size of page table needed to implement the virtual address space of a process
63. In information is recorded magnetically on platters.
Correct : A. magnetic disks
64. The heads of the magnetic disk are attached to a that moves all the heads as a unit.
Correct : B. disk arm
65. The set of tracks that are at one arm position make up a
Correct : D. cylinders
66. The time taken to move the disk arm to the desired cylinder is called the
Correct : C. seek time
67. The time taken for the desired sector to rotate to the disk head is called
Correct : D. rotational latency
68. When the head damages the magnetic surface, it is known as
Correct : B. head crash
69. What is the host controller?
Correct : B. controller at the computer end of the bus
70. controller sends the command placed into it, via messages to the controller.
Correct : C. host, disk
71. What is the disk bandwidth?
Correct : C. the total number of bytes transferred divided by the total time between the first request for service and the completion on the last transfer
72. Whenever a process needs I/O to or from a disk it issues a
Correct : B. system call to the operating system
73. If a process needs I/O to or from a disk, and if the drive or controller is busy then
Correct : A. the request will be placed in the queue of pending requests for that drive
74. Magnetic tape drives can write data at a speed disk drives.
Correct : B. comparable to
75. On media that use constant linear velocity (CLV), the is uniform.
Correct : C. the density of bits per track
76. SSTF algorithm, like SJF of some requests.
Correct : A. may cause starvation
77. In the algorithm, the disk arm starts at one end of the disk and moves toward the other end, servicing requests till the other end of the disk. At the other end, the direction is reversed and servicing continues.
Correct : B. scan
78. In the algorithm, the disk head moves from one end to the other, servicing requests along the way. When the head reaches the other end, it immediately returns to the beginning of the disk without servicing any requests on the return trip.
Correct : C. c-scan
79. The process of dividing a disk into sectors that the disk controller can read and write, before a disk can store data is known as
Correct : C. low-level formatting
80. The data structure for a sector typically contains
Correct : D. all of the mentioned
81. The header and trailer of a sector contain information used by the disk controller such as and
Correct : B. error correcting codes (ecc) & sector number
82. The program initializes all aspects of the system, from CPU registers to device controllers and the contents of main memory, and then starts the operating system.
Correct : C. bootstrap
83. For most computers, the bootstrap is stored in
Correct : C. cache
84. The scheme used in the above question is known as or
Correct : A. sector sparing & forwarding
85. A disk that has a boot partition is called a
Correct : C. boot disk
86. If one or more devices use a common set of wires to communicate with the computer system, the connection is called
Correct : D. bus
87. When device A has a cable that plugs into device B, and device B has a cable that plugs into device C and device C plugs into a port on the computer, this arrangement is called a
Correct : B. daisy chain
88. The present a uniform device- access interface to the I/O subsystem, much as system calls provide a standard interface between the application and the operating system.
Correct : C. device drivers
89. The register is read by the host to get input.
Correct : C. data in
90. The register is written by the host to send output.
Correct : D. data out
91. The hardware mechanism that allows a device to notify the CPU is called
Correct : B. interrupt
92. The determines the cause of the interrupt, performs the necessary processing and executes a return from the interrupt instruction to return the CPU to the execution state prior to the interrupt.
Correct : C. interrupt handler
93. In general the two interrupt request lines are
Correct : A. maskable & non maskable interrupts
94. The are reserved for events such as unrecoverable memory errors.
Correct : A. non maskable interrupts
95. The can be turned off by the CPU before the execution of critical instruction sequences that must not be interrupted.
Correct : C. maskable interrupt
96. The is used by device controllers to request service.
Correct : C. maskable interrupt
97. The interrupt vector contains
Correct : B. the memory addresses of specialized interrupt handlers
98. Division by zero, accessing a protected or non existent memory address, or attempting to execute a privileged instruction from user mode are all categorized as