650+ Operating System (OS) Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Computer Science Engineering (CSE) , Information Technology Engineering (IT) , Bachelor of Science in Computer Science FY (BSc CS) , Bachelor of Computer Applications (BCA) , Bachelor of Science in Computer Science (BSc CS) .

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451.	The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by
A.	the instruction set architecture
B.	page size
C.	physical memory size
D.	number of processes in memory
Answer» A. the instruction set architecture

452.	What is the reason for using the LFU page replacement algorithm?
A.	an actively used page should have a large reference count
B.	a less used page has more chances to be used again
C.	it is extremely efficient and optimal
D.	all of the mentioned
Answer» A. an actively used page should have a large reference count

453.	In segmentation, each address is specified by
A.	a segment number & offset
B.	an offset & value
C.	a value & segment number
D.	a key & value
Answer» A. a segment number & offset

454.	Each entry in a segment table has a
A.	segment base
B.	segment peak
C.	segment value
D.	none of the mentioned
Answer» A. segment base

455.	The segment limit contains the
A.	starting logical address of the process
B.	starting physical address of the segment in memory
C.	segment length
D.	none of the mentioned
Answer» C. segment length

456.	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
Answer» B. between 0 and segment limit

457.	If the offset is legal
A.	it is used as a physical memory address itself
B.	it is subtracted from the segment base to produce the physical memory address
C.	it is added to the segment base to produce the physical memory address
D.	none of the mentioned
Answer» A. it is used as a physical memory address itself

458.	When the entries in the segment tables of two different processes point to the same physical location
A.	the segments are invalid
B.	the processes get blocked
C.	segments are shared
D.	all of the mentioned
Answer» C. segments are shared

459.	The protection bit is 0/1 based on
A.	write only
B.	read only
C.	read – write
D.	none of the mentioned
Answer» C. read – write

460.	If there are 32 segments, each of size 1Kb, then the logical address should have
A.	13 bits
B.	14 bits
C.	15 bits
D.	16 bits
Answer» C. 15 bits

461.	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?
A.	2048
B.	256
C.	64
D.	8
Answer» C. 64

463.	In information is recorded magnetically on platters.
A.	magnetic disks
B.	electrical disks
C.	assemblies
D.	cylinders
Answer» A. magnetic disks

464.	The heads of the magnetic disk are attached to a that moves all the heads as a unit.
A.	spindle
B.	disk arm
C.	track
D.	none of the mentioned
Answer» B. disk arm

465.	The set of tracks that are at one arm position make up a
A.	magnetic disks
B.	electrical disks
C.	assemblies
D.	cylinders
Answer» D. cylinders

466.	The time taken to move the disk arm to the desired cylinder is called the
A.	positioning time
B.	random access time
C.	seek time
D.	rotational latency
Answer» C. seek time

462.	A multilevel page table is preferred in comparison to a single level page table for translating virtual address to physical address because
A.	it reduces the memory access time to read or write a memory location
B.	it helps to reduce the size of page table needed to implement the virtual address space of a process
C.	it is required by the translation lookaside buffer
D.	it helps to reduce the number of page faults in page replacement algorithms
Answer» B. it helps to reduce the size of page table needed to implement the virtual address space of a process

467.	The time taken for the desired sector to rotate to the disk head is called
A.	positioning time
B.	random access time
C.	seek time
D.	rotational latency
Answer» D. rotational latency

468.	When the head damages the magnetic surface, it is known as
A.	disk crash
B.	head crash
C.	magnetic damage
D.	all of the mentioned
Answer» B. head crash

469.	What is the host controller?
A.	controller built at the end of each disk
B.	controller at the computer end of the bus
C.	all of the mentioned
D.	none of the mentioned
Answer» B. controller at the computer end of the bus

470.	controller sends the command placed into it, via messages to the controller.
A.	host, host
B.	disk, disk
C.	host, disk
D.	disk, host
Answer» C. host, disk

471.	What is the disk bandwidth?
A.	the total number of bytes transferred
B.	total time between the first request for service and the completion on the last transfer
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
D.	none of the mentioned
Answer» 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

472.	Whenever a process needs I/O to or from a disk it issues a
A.	system call to the cpu
B.	system call to the operating system
C.	a special procedure
D.	all of the mentioned
Answer» B. system call to the operating system

473.	If a process needs I/O to or from a disk, and if the drive or controller is busy then
A.	the request will be placed in the queue of pending requests for that drive
B.	the request will not be processed and will be ignored completely
C.	the request will be not be placed
D.	none of the mentioned
Answer» A. the request will be placed in the queue of pending requests for that drive

474.	Magnetic tape drives can write data at a speed disk drives.
A.	much lesser than
B.	comparable to
C.	much faster than
D.	none of the mentioned
Answer» B. comparable to

475.	On media that use constant linear velocity (CLV), the is uniform.
A.	density of bits on the disk
B.	density of bits per sector
C.	the density of bits per track
D.	none of the mentioned
Answer» C. the density of bits per track

650+ Operating System (OS) Solved MCQs

The minimum number of page frames that must be allocated to a running process in a virtual memory environment is determined by

What is the reason for using the LFU page replacement algorithm?

In segmentation, each address is specified by

Each entry in a segment table has a

The segment limit contains the

The offset ‘d’ of the logical address must be

If the offset is legal

When the entries in the segment tables of two different processes point to the same physical location

The protection bit is 0/1 based on

If there are 32 segments, each of size 1Kb, then the logical address should have

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?

A multilevel page table is preferred in comparison to a single level page table for translating virtual address to physical address because

In information is recorded magnetically on platters.

The heads of the magnetic disk are attached to a that moves all the heads as a unit.

The set of tracks that are at one arm position make up a

The time taken to move the disk arm to the desired cylinder is called the

The time taken for the desired sector to rotate to the disk head is called

When the head damages the magnetic surface, it is known as

What is the host controller?

controller sends the command placed into it, via messages to the controller.

What is the disk bandwidth?

Whenever a process needs I/O to or from a disk it issues a

If a process needs I/O to or from a disk, and if the drive or controller is busy then

Magnetic tape drives can write data at a speed disk drives.

On media that use constant linear velocity (CLV), the is uniform.

SSTF algorithm, like SJF of some requests.

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.

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.

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

The data structure for a sector typically contains

The header and trailer of a sector contain information used by the disk controller such as and

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.

For most computers, the bootstrap is stored in

The scheme used in the above question is known as or

A disk that has a boot partition is called a

If one or more devices use a common set of wires to communicate with the computer system, the connection is called

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

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.

The register is read by the host to get input.

The register is written by the host to send output.

The hardware mechanism that allows a device to notify the CPU is called

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.

In general the two interrupt request lines are

The are reserved for events such as unrecoverable memory errors.

The can be turned off by the CPU before the execution of critical instruction sequences that must not be interrupted.

The is used by device controllers to request service.

The interrupt vector contains

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

For large data transfers, is used.

A character stream device transfers

476.	SSTF algorithm, like SJF of some requests.
A.	may cause starvation
B.	will cause starvation
C.	does not cause starvation
D.	causes aging
Answer» A. may cause starvation

477.	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.
A.	look
B.	scan
C.	c-scan
D.	c-look
Answer» B. scan

478.	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.
A.	look
B.	scan
C.	c-scan
D.	c-look
Answer» C. c-scan

479.	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
A.	partitioning
B.	swap space creation
C.	low-level formatting
D.	none of the mentioned
Answer» C. low-level formatting

480.	The data structure for a sector typically contains
A.	header
B.	data area
C.	trailer
D.	all of the mentioned
Answer» D. all of the mentioned

481.	The header and trailer of a sector contain information used by the disk controller such as and
A.	main section & disk identifier
B.	error correcting codes (ecc) & sector number
C.	sector number & main section
D.	disk identifier & sector number
Answer» B. error correcting codes (ecc) & sector number

482.	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.
A.	main
B.	bootloader
C.	bootstrap
D.	rom
Answer» C. bootstrap

483.	For most computers, the bootstrap is stored in
A.	RAM
B.	ROM
C.	cache
D.	tertiary storage
Answer» B. ROM

484.	The scheme used in the above question is known as or
A.	sector sparing & forwarding
B.	forwarding & sector utilization
C.	backwarding & forwarding
D.	sector utilization & backwarding
Answer» A. sector sparing & forwarding

485.	A disk that has a boot partition is called a
A.	start disk
B.	end disk
C.	boot disk
D.	all of the mentioned
Answer» C. boot disk