Mapping Functions

Computer Organization Questions and Answers – Mapping Functions

This set of Computer Organisation and Architecture MCQ focuses on “Mapping Functions”.

1. The memory blocks are mapped onto the cache with the help of ______.
a) Hash functions
b) Vectors
c) Mapping functions
d) None of the above
View Answer

Answer:c
Explanation: The mapping functions are used to map the memory blocks on to their corresponding cache block.

2. During a write operation if the required block is not present in the cache then ______ occurs.
a) Write latency
b) Write hit
c) Write delay
d) Write miss
View Answer

Answer:d
Explanation: This indicates that the operation has missed and it brings the required block into cache.

3. In ________ protocol the information is directly written into main memory.
a) Write through
b) Write back
c) Write first
d) None of the above
View Answer

Answer:a
Explanation: In case of the miss, then the data gets written directly in main memory.

4. The only draw back of using the early start protocol is _______.
a) Time delay
b) Complexity of circuit
c) Latency
d) High miss rate
View Answer

Answer:b
Explanation: In this protocol, the required block is read and directly sent to the processor.

5. The method of mapping the consecutive memory blocks to consecutive cache blocks is called ______.
a) Set associative
b) Associative
c) Direct
d) Indirect
View Answer

Answer:c
Explanation: This method is most simple to implement as it involves direct mapping of memory blocks.

6. While using the direct mapping technique, in a 16 bit system the higher order 5 bits is used for ________.
a) Tag
b) Block
c) Word
d) Id
View Answer

Answer:a
Explanation: The tag is used to identify the block mapped onto one particular cache block.

7. In direct mapping the presence of the block in memory is checked with the help of block field.
a) True
b) False
View Answer

Answer:b
Explanation: The tag field is usd to check the presence of a mem block.

8. In associative mapping, in a 16 bit system the tag field has ______ bits.
a) 12
b) 8
c) 9
d) 10
View Answer

Answer:a
Explanation: The Tag field is used as an id for the different memory blocks mapped to the cache.

9. The associative mapping is costlier than direct mapping.
a) True
b) False
View Answer

Answer:a
Explanation: In associative mapping all the tags have to be searched to find the block.

10. The technique of searching for a block by going through all the tags is ______.
a) Linear search
b) Binary search
c) Associative search
d) None of the above
View Answer

Answer:c
Explanation: None.

11. The set associative map technique is a combination of the direct and associative technique.
a) True
b) False
View Answer

Answer:a
Explanation: The combination of the efficiency of the associative method and the cheapness of the direct mapping, we get the set-associative mapping.

12. In set-associative technique, the blocks are grouped into ______ sets.
a) 4
b) 8
c) 12
d) 6
View Answer

Answer:d
Explanation: The set-associative technique groups the blocks into different sets.

13. A control bit called ____ has to be provided to each blocj in set-associative.
a) Idol bit
b) Valid bit
c) Reference bit
d) All of the above
View Answer

Answer:b
Explanation: The valid bit is used to indicate that the block holds valid information.

14. The bit used to indicate whether the block was recently used or not is _______.
a) Idol bit
b) Control bit
c) Refernece bit
d) Dirty bit
View Answer

Answer:d
Explanation: The dirty bit is used to show that the block was recently modified and for replacement algorithm.

15. Data which is not up-to date is called as _______.
a) Spoilt data
b) Stale data
c) Dirty data
d) None of the above
View Answer

Answer:b
Explanation: None.

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