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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401.	The is used as an index into the page table.
A.	frame bit
B.	page number
C.	page offset
D.	frame offset
Answer» B. page number

402.	The table contains the base address of each page in physical memory.
A.	process
B.	memory
C.	page
D.	frame
Answer» C. page

403.	The size of a page is typically
A.	varied
B.	power of 2
C.	power of 4
D.	none of the mentioned
Answer» B. power of 2

404.	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.
A.	m, n
B.	n, m
C.	m – n, m
D.	m – n, n
Answer» D. m – n, n

405.	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.
A.	page
B.	mapping
C.	frame
D.	memory
Answer» C. frame

406.	Paging increases the time.
A.	waiting
B.	execution
C.	context – switch
D.	all of the mentioned
Answer» C. context – switch

407.	Smaller page tables are implemented as a set of
A.	queues
B.	stacks
C.	counters
D.	registers
Answer» D. registers

408.	The page table registers should be built with
A.	very low speed logic
B.	very high speed logic
C.	a large memory space
D.	none of the mentioned
Answer» B. very high speed logic

409.	For larger page tables, they are kept in main memory and a points to the page table.
A.	page table base register
B.	page table base pointer
C.	page table register pointer
D.	page table base
Answer» A. page table base register

410.	For every process there is a
A.	page table
B.	copy of page table
C.	pointer to page table
D.	all of the mentioned
Answer» A. page table

411.	Time taken in memory access through PTBR is
A.	extended by a factor of 3
B.	extended by a factor of 2
C.	slowed by a factor of 3
D.	slowed by a factor of 2
Answer» D. slowed by a factor of 2

412.	Each entry in a translation lookaside buffer (TLB) consists of
A.	key
B.	value
C.	bit value
D.	constant
Answer» A. key

413.	If a page number is not found in the TLB, then it is known as a
A.	tlb miss
B.	buffer miss
C.	tlb hit
D.	all of the mentioned
Answer» A. tlb miss

415.	The percentage of times a page number is found in the TLB is known as
A.	miss ratio
B.	hit ratio
C.	miss percent
D.	none of the mentioned
Answer» B. hit ratio

416.	Memory protection in a paged environment is accomplished by
A.	protection algorithm with each page
B.	restricted access rights to users
C.	restriction on page visibility
D.	protection bit with each page
Answer» D. protection bit with each page

414.	An uniquely identifies processes and is used to provide address space protection for that process.
A.	address space locator
B.	address space identifier
C.	address process identifier
D.	none of the mentioned
Answer» B. address space identifier

417.	When the valid – invalid bit is set to valid, it means that the associated page
A.	is in the tlb
B.	has data in it
C.	is in the process’s logical address space
D.	is the system’s physical address space
Answer» C. is in the process’s logical address space

418.	When there is a large logical address space, the best way of paging would be
A.	not to page
B.	a two level paging algorithm
C.	the page table itself
D.	all of the mentioned
Answer» B. a two level paging algorithm

419.	is the concept in which a process is copied into the main memory from the secondary memory according to the requirement.
A.	paging
B.	demand paging
C.	segmentation
D.	swapping
Answer» B. demand paging

420.	The pager concerns with the
A.	special support from hardware is required
B.	special support from operating system is essential
C.	special support from both hardware and operating system is essential
D.	user programs can implement dynamic loading without any special support from hardware or operating system
Answer» D. user programs can implement dynamic loading without any special support from hardware or operating system

421.	In paged memory systems, if the page size is increased, then the internal fragmentation generally
A.	becomes less
B.	becomes more
C.	remains constant
D.	none of the mentioned
Answer» B. becomes more

422.	Swap space exists in
A.	primary memory
B.	secondary memory
C.	cpu
D.	none of the mentioned
Answer» B. secondary memory

423.	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
Answer» C. page fault occurs

424.	Effective access time is directly proportional to
A.	page-fault rate
B.	hit ratio
C.	memory access time
D.	none of the mentioned
Answer» A. page-fault rate

425.	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
D.	none of the mentioned
Answer» A. oldest page is chosen

650+ Operating System (OS) Solved MCQs

The is used as an index into the page table.

The table contains the base address of each page in physical memory.

The size of a page is typically

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.

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.

Paging increases the time.

Smaller page tables are implemented as a set of

The page table registers should be built with

For larger page tables, they are kept in main memory and a points to the page table.

For every process there is a

Time taken in memory access through PTBR is

Each entry in a translation lookaside buffer (TLB) consists of

If a page number is not found in the TLB, then it is known as a

An uniquely identifies processes and is used to provide address space protection for that process.

The percentage of times a page number is found in the TLB is known as

Memory protection in a paged environment is accomplished by

When the valid – invalid bit is set to valid, it means that the associated page

When there is a large logical address space, the best way of paging would be

is the concept in which a process is copied into the main memory from the secondary memory according to the requirement.

The pager concerns with the

In paged memory systems, if the page size is increased, then the internal fragmentation generally

Swap space exists in

When a program tries to access a page that is mapped in address space but not loaded in physical memory, then

Effective access time is directly proportional to

In FIFO page replacement algorithm, when a page must be replaced

Virtual memory allows

A process is thrashing if

The ability to execute a program that is only partially in memory has benefits like

Virtual memory is normally implemented by

Segment replacement algorithms are more complex than page replacement algorithms because

A swapper manipulates whereas the pager is concerned with individual of a process.

Using a pager

The valid – invalid bit, in this case, when valid indicates?

A page fault occurs when?

When a page fault occurs, the state of the interrupted process is

When a process begins execution with no pages in memory?

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

When the page fault rate is low

Locality of reference implies that the page reference being made by a process

Which of the following page replacement algorithms suffers from Belady’s Anomaly?

In question 2, if the number of page frames is increased to 4, then the number of page transfers

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

Users that their processes are running on a paged system.

If no frames are free, page transfer(s) is/are required.

A FIFO replacement algorithm associates with each page the

What is the Optimal page – replacement algorithm?

LRU page – replacement algorithm associates with each page the

What are the two methods of the LRU page replacement policy that can be implemented in hardware?

When using counters to implement LRU, we replace the page with the

There is a set of page replacement algorithms that can never exhibit Belady’s Anomaly, called

426.	Virtual memory allows
A.	execution of a process that may not be completely in memory
B.	a program to be smaller than the physical memory
C.	a program to be larger than the secondary storage
D.	execution of a process without being in physical memory
Answer» A. execution of a process that may not be completely in memory

427.	A process is thrashing if
A.	it is spending more time paging than executing
B.	it is spending less time paging than executing
C.	page fault occurs
D.	swapping can not take place
Answer» A. it is spending more time paging than executing

428.	The ability to execute a program that is only partially in memory has benefits like
A.	the amount of physical memory cannot put a constraint on the program
B.	programs for an extremely large virtual space can be created
C.	throughput increases
D.	all of the mentioned
Answer» D. all of the mentioned

429.	Virtual memory is normally implemented by
A.	demand paging
B.	buses
C.	virtualization
D.	all of the mentioned
Answer» A. demand paging

430.	Segment replacement algorithms are more complex than page replacement algorithms because
A.	segments are better than pages
B.	pages are better than segments
C.	segments have variable sizes
D.	segments have fixed sizes
Answer» C. segments have variable sizes

431.	A swapper manipulates whereas the pager is concerned with individual of a process.
A.	the entire process, parts
B.	all the pages of a process, segments
C.	the entire process, pages
D.	none of the mentioned
Answer» C. the entire process, pages

432.	Using a pager
A.	increases the swap time
B.	decreases the swap time
C.	decreases the swap time & amount of physical memory needed
D.	increases the amount of physical memory needed
Answer» C. decreases the swap time & amount of physical memory needed

433.	The valid – invalid bit, in this case, when valid indicates?
A.	the page is not legal
B.	the page is illegal
C.	the page is in memory
D.	the page is not in memory
Answer» C. the page is in memory

434.	A page fault occurs when?
A.	a page gives inconsistent data
B.	a page cannot be accessed due to its absence from memory
C.	a page is invisible
D.	all of the mentioned
Answer» B. a page cannot be accessed due to its absence from memory

435.	When a page fault occurs, the state of the interrupted process is
A.	disrupted
B.	invalid
C.	saved
D.	none of the mentioned
Answer» C. saved