Advanced Database Management System - Tutorials and Notes: Operating systems multiple choice questions for exams - Set 17

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Friday, 24 April 2020

Operating systems multiple choice questions for exams - Set 17

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

View Answer

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

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

View Answer

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.

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

View Answer

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.

4. Main memory of computer system is also called

(a) non volatile
(b) volatile
(c) reserved
(d) large

View Answer

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.

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

View Answer

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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