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Operating systems exams - multiple choice questions (MCQ) and answers
Operating
Systems MCQ questions and answers – Set 17
1. If the physical address generated was
300 and the relocation register was set to 100, what was the corresponding
logical address?
(a) 400
(b) 200
(c) 300
(d) 399
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Ans : (b)
Answer: (b) 200
Relocation register is also called
as base register
Physical
address = logical address + base register.
Logical
address = physical address – base register = 300 – 100 = 200
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2. Which of the following is not a
benefit of virtual memory?
(a) speed up of process
creation
(b)
increases in the effective access time of memory
(c) the possibility of
sharing memory between processes
(d) the ability to address
more memory than exists in RAM
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Ans : (b)
Answer: (b) increases in
the effective access of time of memory
An
increase in the effective access time of memory is the disadvantage of paging
in OS.
The
primary benefits of virtual memory include freeing applications from having
to manage a shared memory space, increased security due to memory isolation,
and being able to conceptually use more memory than might be physically
available, using the technique of paging.
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3. Which of the following allocation
methods ensures that only one access is needed to get a disk block using direct
access?
(a) Hashed allocation
(b) Linked allocation
(c)
Contiguous allocation
(d) Indexed allocation
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Ans : (c)
Answer: (c) Contiguous
allocation
In
contiguous allocation file allocation method, each file occupies a set of
consecutive addresses on disk. The directory entry for each file contains the
file name, starting address of the first block, block address = sector id
(e.g., block = 4K) and length in blocks. Suppose there is a file with length
n blocks and starting from location block b, then the file occupies blocks b,
b + 1, b + 2, …, b + n-1.
To
access directly (direct access), if we know the address of starting block b, we
can easily get the address of kth block as (b+k). Hence, only one access is needed to get a disk block.
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4. Main memory of computer system is also
called
(a) non volatile
(b)
volatile
(c) reserved
(d) large
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Ans : (b)
Answer: (b) volatile
Main
memory (RAM) of a computer is also called volatile memory because it loses
the information stored in it if power is removed.
Define
main memory
Main
memory is the primary, internal workspace in the computer, commonly known as
RAM (random access memory).
Main
memory is where programs and data are kept when the processor is actively
using them. When programs and data become active, they are copied from
secondary memory into main memory where the processor can interact with them.
A copy remains in secondary memory.
Main
memory is intimately connected to the processor, so moving instructions and
data into and out of the processor is very fast.
.
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5. Memory management technique in which
system stores and retrieves data from secondary storage for use in main memory
is called ______
(a) Fragmentation
(b) Mapping
(c)
Paging
(d) None of the above
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Ans : (c)
Answer: (c) Paging
In
operating systems, paging is a memory management concept by which a computer
stores and retrieves data from secondary storage for use in main memory.
Physical
memory is broken into fixed size blocks called frames.
Logical memory is also broken into blocks of the same size called pages. When a process is to be executed, its pages
are loaded into any available memory frames from the backing store. The
backing store is divided into fixed sized blocks. Those are of the same size
as the memory frames.
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