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OSG 1-100 - abc

Operating System (Trường Đại học FPT)

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1. Which of the following statements about the CPU's handling interrupts is incorrect?
None of the other choices
The CPU branches to a new instruction sequence
The hardware saves the old PC location
The processor ceases to execute the current sequence of instructions

2. ____ is the partitioning of a single server, each of which can support a different operating
Multiprocessing
Multithreading
Shared processing
Virtualization

3. Consider a computer system that has cache memory, main memory (RAM) and disk, and OS
uses virtual memory. It takes 1 nsec to access a word from the cache, 10 nsec to access a word
from RAM, and 10 msec to access a word from the disk. If the cache hit rate is 95% and main
memory hit rate is 99%, what is average time to access a word?
1.445 nsec
5,001.445 nsec
5,000.495 nsec
5,000.95 nsec

4. Booting a general purpose computer involves the following steps except

Loading the OS
Loading the command interpreter
Loading one or more bootstrap loaders
Execution of a ROM-based POST sequence

5. As one proceeds down the memory hierarchy (from inboard memory to offline storage),
which of the following conditions is correct?
Decreasing access time
None of the other choices
Decreasing cost per bit
Decreasing capacity

6. The two basic types of processor registers are:

User-visible and user-invisible registers
None of the other choices
Control and Status registers
General and special registers

7. Consider a computer system that has cache memory, main memory (RAM) and disk, and OS
uses virtual memory. It takes 2 nsec to access a byte from the cache, 20 nsec to access a byte

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from RAM, and 10 msec to access a block of 1000 bytes from the disk. If a book has 1000
pages, each with 50 lines of 80 characters each. How long it will take to electronically scan the
text for the case of the master copy being in each of the level as one proceeds down the
memory hierarchy (from inboard memory to offline storage)?
1 msec, 10 msec, 5 sec
1 msec, 10 msec, 10 sec
2 msec, 20 msec, 10 sec
4 msec, 40 msec, 20 sec

8. The main characteristics of layered system does not include:

Upper layer can only call functions of closely lower layer
Each layer has well defined functions
Each layer runs independently
Many layers

9. Which of special register in the CPU points to the top of the current stack in the memory?
PC
PSW
IR
SP

10. A CPU may have multiple execution units, so that can carry out multiple instructions in the
same time is called:
None of the other choices
Multicore
Pipeline
Superscalar

11. Consider a computer system that has cache memory, main memory (RAM) and disk, and OS
uses virtual memory. It takes 2 nsec to access a word from the cache, 20 nsec to access a word
from RAM, and 10 msec to access a word from the disk. If the cache hit rate is 95% and main
memory hit rate is 99%, what is average time to access a word? *
5,000.99 nsec
5,002.89 nsec
2.89 nsec
5,001.9 nsec

12. Information that must be saved prior to the processor transferring control to the interrupt
handler routine includes:
PSW
None of the other choices
PSW and Contents of processor registers
PSW and PC

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13. Examples of general purpose stored program computers include the following except
Personal computers
Network servers
Workstations
MP3 player

14. The ways that input/output can be done is?

DMA (Direct Memory Access)
All of the other choices
Busy waiting
Interrupt

15. List of memory location, that contains the executable program, the program's data, and its
stack is called:
set of resources
all of the other choices
address memory
address space

16. Which is not an example of a resource that is commonly space-multiplexed?

Video RAM
Main memory
CPU
Hard drive

17. Which of the following is not a step in the boot process?

The BIOS is activated by powering on the CPU
Configuration and customization settings are checked
The antivirus program checks all files for viruses
The operating system is loaded into RAM

18. Which of special register contains the Mode Bit (user or kernel)?
Program Counter (PC)
None of the other choices
Program Status Word (PSW)
Instruction Register (IR)

19. Which is not an example of a resource that is commonly time-multiplexed?

CPU
Graphics accelerator

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Main memory
Network interface

20. Where is the position of the operating system in computer system:

Above the hardware and under the user interface program
Between the user interface program and the application Program
In user space
None of the other choices

21. Which of the main bus in the IBM PC computer that can run at 66 MHz and transfer 8 bytes at
a time?
PCI (Peripheral Component Interconnect)
ISA (Industry Standard Architecture)
None of the other choices
ISA and PCI

22. Which of the following statements about Electrically Erasable PROM (EEPROM) is correct?
Can be erased and rewritten
Unprogrammable
Volatile
None of the other choices

23. The major operating system services provide mechanisms for secure and efficient are:
Communication between processes
All of the other choices
Execution of a program,I/O operations performed by it,and detecting and reporting errors caused by it
File manipulation

24. Which of the following instructions should be allowed only in kernel mode?
ADD of two numbers
AND of two numbers
Disable all interrupts
Read the time-of-day clock

25. As one proceeds down the memory hierarchy (from inboard memory to offline storage),
which of the following conditions is correct?
Increasing cost per bit
Decreasing access time
None of the other choices
Increasing capacity

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26. The main characteristics of exokernels is:

A subset of the resources is given in user mode
The program, called the exokernel runs in kernel mode
Exokernels need only keep track of which virtual machine assigned which resource
All of the other choices

27. The language of the CPU is known as its

None of the other choices
Instruction set
Register set
Control unit set

28. Which of special register contains the condition code bits, the CPU priority, the mode bit and
other control bits)?
None of the other choices
Program Counter (PC)
Instruction Register (IR)
Program Status Word (PSW)

29. Which of the following statements about Random Access Memory (RAM) is correct?
Is volatile
Stores all the files on the computer
Can only be read sequentially
Is typically faster than cache memory

30. VMware Workstation is:

Type 2 Hypervisor
Host Operating system
Type 1 Hypervisor
Guest Operating system

31. Which of the following is correct about advantages of layered system?

None of the other choices
Easier to debug from lower to upper layer
Easier to extend and Easier to debug from lower to upper layer
Easier to extend

32. Which of the following instructions should be allowed only in kernel mode?
All of the other choices
Change the memory map
Set the time-of-day clock
Disable all interrupts

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33. Which of the following statements about the CMOS is incorrect?

Is volatile
To contain BIOS
To hold the configuration parameters
To hold the current time and date

34. What part of the boot process determines whether the peripheral devices are working
properly?
ROM
POST
CMOS
BIOS

35. The four main structural elements of a computer system are:

Processor, Registers, I/O Modules, Main Memory
None of the other choices
Processor, Registers, Main Memory, System Bus
Processor, Main Memory, I/O Modules, System Bus

36. As one proceeds down the memory hierarchy (from inboard memory to offline storage),
which of the following conditions is correct? *
Decreasing capacity
None of the other choices
Increasing cost per bit
Increasing access time

37. What is not a main function of an operating system?

Provide the users with an extended (virtual) machine
Manage the I/O devices
Provide user interfaces
Support virtual memory

38. As one proceeds down the memory hierarchy (from inboard memory to offline storage), the
following conditions apply:
Increasing capacity
Decreasing cost per bit
All of the other choices
Increasing access time

39. Which of the following is not a operating mode of CPU ?

Kernel mode

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User mode
Management mode
None of the other choices

40. A special register that contains the address of the next instruction to be fetched is called:
Instruction Register (IR)
All of the other choices
Program Counter (PC)
Program Status Word (PSW)

41. Which of the following operating systems is a example of monolithic system?

MS-DOS
Mac OS
UNIX
Windows XP

42. A CPU may have two or more complete processors, so that can carry out multiple threads in
the same time is called:
Pipeline
Multicore
None of the other choices
Superscalar

43. Which of the following instructions should be allowed in user mode?

Read the time-of-day clock
Set the time-of-day clock
Disable all interrupts
Change the memory map

44. The main bus in the IBM PC computer are:

PCI (Peripheral Component Interconnect)
ISA and PCI
None of the other choices
ISA (Industry Standard Architecture)

45. The general role of an operating system is to:

Provide a set of services to system users
Act as an interface between various computers
None of the other choices
Manage files for application programs

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46. The operating system structure in which the communication between requesting process and
responding process is message passing?
All of the other choices
Monolithic Systems
MS - DOS
Client - Server Model

47. What is interrupt vector?

Part of memory which contains the addresses of interrupt handlers
The addresses of interrupt handlers
A signal an I/O device sends to CPU
None of the other choices

48. Which of the following actions generates an external interrupt?

A page that does not exist in the main memory is accessed by the virtual storage management
An input/output operation is completed
Division by zero occurs
A system call instruction is executed

49. An operating system

Manages software resources in a computer system
Deals with complex hardware resources and provides the user a virtual/extended machine that is
much easier to deal with than the physical machine
Manages hardware resources in a computer system
All of the other choices

50. A CPU may have separate fech, decode and execute units, so that can carry out three steps of
the three instructions in the same time is called:
Pipeline
None of the other choices
Superscalar
Multicore

51. What does the virtual machine monitor do?

Does the multiprogramming
Provides sevral virtual machines to the next layer up
All of the other choices
Runs on the bare hardware.

52. Which is the fastest bus in the IBM PC computer?

PCI (Peripheral Component Interconnect)
IDE (Integrated Drive Electronic)

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ISA (Industry Standard Architecture)

USB (Universal Serial BUS)
53. Consider a computer system that has cache memory, main memory (RAM) and disk, and OS
uses virtual memory. It takes 2 nsec to access a word from the cache, 10 nsec to access a word
from RAM, and 10 msec to access a word from the disk. If the cache hit rate is 95% and main
memory hit rate is 99%, what is average time to access a word?
5,000.495 nsec
5,001.9 nsec
2.395 nsec
5,002.395 nsec

54. Which of the following conditions that causes the processes to be terminated, when the
processes executes a system call tell the OS to fininsh some other process?
Normal exit (voluntary)
Error exit (voluntary)
Fatal error (involuntary)
Killed by another process (involuntary)

55. Which of the following conditions that causes the processes to be terminated, when the
processes have a program bug?
Fatal error (involuntary)
Error exit (voluntary)
Normal exit (voluntary)
Killed by another process (involuntary)

56. Operating system abstraction supports the ability to have ______ operation even when there
is only one CPU available
Multiple
none of the other choices
parallel
Pseudoparallelism

57. What is the "sequential processes" concept?

There are both many CPU and many PC
None of the other choices
All process is executed in concurrency
No concurrency inside a process; everything happens sequentiall

58. How many percent of the CPU time is wasted, when a computer system has enough room to
hold two program and these programs are idle waiting for I/O half the time?
75%
50%
25%

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None of the other choices

59. ____ is the act of allowing only one process to have access to a dedicated resource.
Mutual exclusion
Circular wait
No preemption
Resource holdin

60. Which of the following statements about user-level threads and kernel-level threads is
correct?
None of the other choices
Both user-level threads and kernel-level threads can write into each other's memory space.
Kernel-level thread scheduling is faster than user-level thread scheduling
Both user-level threads and kernel-level threads use OS services via system calls

61. Which of the following cannot be shared among different threads of a process?
Stack
Process code
File handles
Process data

62. A ____ is a portion of a process that can run independently

Thread
program
miniprocess
subprocess

63. Five batch jobs A through E, arrive at a computer center at almost the same time. They have
estimated running times of 8, 6, 2, 10, and 4 minutes. Determine the average waiting time for
FCFS scheduling. Ignore process switching overhead.
18 minutes
18.8 minutes
17 minutes
12,8 minutes

64. Which of the following is appropriate to release page table and pages?
Process creation
Process termination time
Page fault time
Process execution

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65. Which of the events that causes the processes to be created, when the operation system
creates a new process and runs the next job from the input queue?
Initiation of a batch job
User request to create a new process
System initialization
Execution of a process creation system call

66. How many percent of the CPU time is wasted, when a computer system has enough room to
hold two program and these programs are idle waiting for I/O 10% of the time?
99%
1%
None of the other choices
90%

67. What happens when a thread calls Down (S) when it wants to enter its critical section, where
S is a binary semaphore set to 1?
The thread is blocked and added to a queue of waiting threads.
The semaphore is set to 2.
The thread is allowed to enter its critical section and S is decremented.
None of the other choices

68. Which of the following statements is a hardware solution to the critical region problem?
TSL
Semaphore
None of the other choices
Shared memory

69. Which of the following is not true about process hierarchy?

Window has no concept of a process hierarchy
In Unix, a process and all its children and further descendants together form a process group
A process creates child process. The child process can itself creates more processes, forming a process
hierarchy
A process may have more than one parent

70. Which conditions of mutual exclusion does the Strict Alternation (Software proposal) violate
No process running outside its critical region may block another process
No assumptions made about speeds or numbers of CPUs
No process must wait forever to enter its critical region
No two processes simultaneously in critical region

71. Five batch jobs A through E, arrive at a computer center at almost the same time. They have
estimated running times of 8, 6, 2, 10, and 4 minutes. Their (externally determined) priorities

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are 3, 5, 2, 1, and 4, respectively, with 5 being the highest priority. Determine the average
waiting time for Priority scheduling. Ignore process switching overhead.
16,8 minutes
12,8 minutes
54 minutes
10,8 minutes

72. Which statement about disadvantage of Disabling interrupts, (the hardware solution to the
critical region problem) is correct?
Permit process use command privileges: Danger!
If process is locked in Critical Section: System Halt
All of the other choices
Don't ensure Mutual Exclusion for the system with N CPUs

73. How many percent is CPU utilization, when a computer system has enough room to hold two
program and these programs are idle waiting for I/O 10% of the time?
1%
99%
None of the other choices
90%

74. What is the purpose of process synchronization?

Avoid race condition
None of the other choices
Let different users run different processes independently
Avoid deadlock

75. Which of the following operating system has the concept of a process hierarchy?
Win32
CP/M
MS-DOS
Unix

76. OS Windows use system call_____, while OS Unix use system call______ to terminate
processes normally
terminate; ExitProcess
exit; ExitProcess
ExitProcess; exit
ExitProcess; terminate

77. Which of the following process state transitions is correct, when the scheduler picks a process
from the ready queue to run?

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Running -> ready

Ready -> running
Blocked (waiting) -> ready
Running -> Blocked (waiting)

78. In a single processor system, mutual exclusion can be guaranteed by:

Overlapping processes
Interleaving processes
Disabling interrupts
All of the other choices

79. In order to implement mutual exclusion on a critical resource for competing processes, only
one program at a time should be allowed:
None of the other choices
To exhibit cooperation
To perform message passing
In the critical region of the program

80. Which of the following process state transitions is illegal?

Blocked (waiting) -> ready
Ready -> Blocked (waiting)
Running -> Blocked (waiting)
Running -> ready

81. Which of the following conditions that causes the processes to be terminated, when a
processes have done their work?
Normal exit (voluntary )
Error exit (voluntary)
Fatal error (involuntary)
Killed by another process (involuntary)

82. Which of the following is not correct about user-level threads?

User-level threads are more efficient than kernel threads, in the sense that they do not need kernel
calls to switch among threads
With user-level threads, customized scheduling algorithms cannot be implemented
User-level threads cannot be preempted by clock interrupts unless the whole process' quantum has
been used up
If one user-level thread makes a blocking system call, the system will block the entire process (which
contains that user-level thread)

83. Which of the following about Atomic action is true?

Possibly going to sleep

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All of the other choices

Checking the value
Changing the value

84. A entry of the Process table is called:

Process control block
Process management block
All of the other choices
Process check block

85. What is Software proposal in the solution of Mutual exclusion with Busy waiting
Peterson's Solution
All of the other choices
Lock Variables
Strict Alternation

86. Which conditions of mutual exclusion does the Lock Variables (Software proposal) violate
No assumptions made about speeds or numbers of CPUs
No two processes simultaneously in critical region
No process must wait forever to enter its critical region
No process running outside its critical region may block another process

87. A process where no concurrency inside process; everything happens sequentially is called:
Random access process
Sequential process
Sequential access process
None of the other choices

88. When selecting the proper time quantum it should be long enough to allow ____ percent of
the CPU cycles to run to completion
40
100
80
20

89. Five batch jobs A through E, arrive at a computer center at almost the same time. They have
estimated running times of 8, 6, 2, 10, and 4 minutes. Determine the average waiting time for
SJF (Shortest job first) scheduling. Ignore process switching overhead.
18.8 minutes
6 minutes
8 minutes
14 minutes

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90. Five batch jobs A through E, arrive at a computer center at almost the same time. They have
estimated running times of 8, 6, 2, 10, and 4 minutes. . Determine the average turnaround
time for FCFS schedulingf. Ignore process switching overhead.
20 minutes
18 minutes
17 minutes
18.8 minutes

91. How many percent is CPU utilization, when a computer system has enough room to hold two
program and these programs are idle waiting for I/O half the time?
75%
50%
25%
None of the other choices

92. A computer has 2GB RAM of which the operating system occupies 1GB.The processes are all
450 MB and have the same characteristics. How many percent of the CPU time is wasted,
when these programs are idle waiting for I/O 20% of the time?
90%
None of the other choices
4%
96%

93. How many ways are Thread implemented?

3
2
1
4

94. What is not a field in the process table that relates memory management?
Pointer to data segment info
Pointer to stack segment info
Pointer to text segment info
Pointer to program segment info

95. Which is the correct description of transitions between process states below? (see picture)
1: Process blocks for input; 2: Input becomes available; 3: Scheduler picks another process; 4:
Scheduler picks this process
1: Process blocks for input; 2: Scheduler picks this process; 3: Scheduler picks another process; 4:
Input becomes available
1: Process blocks for input; 2: Input becomes available; 3: Scheduler picks this process; 4: Scheduler

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picks another process

1: Process blocks for input; 2: Scheduler picks another process; 3: Scheduler picks this process; 4:
Input becomes available

96. A computer has 2GB RAM of which the operating system occupies 1GB. The processes are all
450 MB and have the same characteristics. How many percent is CPU utilization when these
programs are idle waiting for I/O 20% of the time?
90%
None of the other choices
96%
4%

97. Which of the events that causes the processes to be created, when a running process creates
one or more new process to help it to do its job?
Execution of a process creation system call
Initiation of a batch job
User request to create a new process
System initialization

98. The following requirement must be met by any facility or capability that is to provide support
for mutual exclusion:
Only one process at a time can be allowed into a critical section
No assumption can be made about relative process speeds
All of the other choices
A process remains in its critical region for a finite time only

99. Which is a advantage of implementing threads in the kernel?

None of the other choices
Is good for multiprocessor architecture and if one thread is blocked does not cause the other thread
to be blocked
If one thread is blocked does not cause the other thread to be blocked
Is good for multiprocessor architecture

100. Critical Region (Section) concept used in interprocess communication is:

A part of shared memory
None of the other choices
A part of the program where the shared memory is accessed
A part of shared data

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