MCQ in operating system with answers

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Operating Systems (OS) MCQ Set - 6

1. What does a time-sharing system need that a multi-programming system does not?

a. Trap mechanism

b. Kernel mode execution privileges

c. Shorter time slices

d. Interval Timer

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Ans : (d)

Answer: (d) In time-sharing system, the processor time is shared between multiple user programs simultaneously. It has a fixed time slice. Multi-programming is the allocation of more than one concurrent program on a computer system and its resources. Multi-programming allows using the CPU effectively by allowing various users to use the CPU and I/O devices effectively. Hence, it has no fixed time slice.

2. In Intel PC architecture, the Master Boot Record (MBR): contains code that…

a. Loads the operating system.

b. Loads the system BIOS.

c. Loads the Volume Boot Code.

d. Allows the user to choose which operating system to load.

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Ans : (c)

Answer: (c) A master boot record (MBR) is a kind of boot sector stored on a hard disk drive or other storage device that contains the necessary computer code to start the boot process. The MBR's boot code uses the volume boot code of that specific partition to identify where the system partition is.

3. Consider a disk with the following characteristics;

Find the storage capacity of each cylinder.

• Number of surfaces: 8 (= 2³)

• Number of tracks / surface: 512 K (= 2¹⁹)

• Number of bytes / track: 8 MB (= 2²³ bytes)

• Number of sectors / track: 8 K (= 2¹³)

• On-disk cache: 16 MB (= 2²⁴ bytes)

a. 1 MB

b. 8 MB

c. 64 MB

d. 242 bytes

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Ans : (c)

Answer: (c) Each track of all the disk surfaces together form a cylinder. Hence, the number of tracks per cylinder = number of disk surfaces = 8. Capacity per cylinder = bytes per track * tracks per cylinder                                       = 223 * 8 = 226 bytes/cylinder                                       = 67108864 bytes = 64 MB

4. Which of the following has the fastest access times?

a. Cache

b. Registers

c. Main memory

d. Flash memory

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Ans : (b)

Answer: (b) Registers are temporary memory units that store data and are located in the processor, instead of in RAM, so data can be accessed and stored faster.

5. Which of the following defines mutual exclusion?

a. A set of processes are prevented from running because higher priority processes keep getting in ahead of them

b. A set of processes is waiting for an event that only another process in the set can cause

c. A set of processes are prevented from simultaneously accessing a shared data structure

d. A situation when a system tries to perform two or more operations at the same time.

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Ans : (c)

Answer: (c) A mutual exclusion is a program object that prevents simultaneous access to a shared resource. This is used in concurrent programming with a critical section, a piece of code in which processes or threads access a shared resource.

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