This set of Cache Memory MCQ covers important concepts of Computer Organization and Architecture (COA) related to cache memory, mapping techniques, locality of reference, cache replacement policies, write policies, and cache performance. Useful for GATE, IBPS IT Officer, university semester exams, and other competitive examinations.
Topic: Computer Organization and Architecture (Cache Memory) | Set: 1
Difficulty: Easy to Medium | Total Questions: 15
Cache Memory MCQ
Q1. Which principle states that if a memory location is accessed, it is likely to be accessed again soon?
- A. Spatial Locality
- B. Temporal Locality
- C. Access Locality
- D. Simultaneous Locality
View Answer & Explanation
Answer: B. Temporal Locality
Explanation: Temporal Locality refers to the reuse of specific data and/or resources within a relatively small time duration.
Q2. Which type of memory is used to bridge the speed gap between the CPU and Main Memory?
- A. RAM
- B. ROM
- C. Cache Memory
- D. Secondary Storage
View Answer & Explanation
Answer: C. Cache Memory
Explanation: Cache memory is a high-speed buffer that stores frequently used data to improve CPU performance.
Q3. A “Cache Hit” occurs when:
- A. Data is found in Main Memory
- B. Data is found in the Cache
- C. Data must be fetched from the Disk
- D. The CPU is idle
View Answer & Explanation
Answer: B. Data is found in the Cache
Explanation: A hit indicates the requested data was successfully located in the faster cache layer.
Q4. Which of the following is the fastest memory in a computer system?
- A. Main Memory
- B. Cache Memory
- C. Magnetic Disk
- D. Optical Disk
View Answer & Explanation
Answer: B. Cache Memory
Explanation: Cache memory (SRAM) has much lower access times compared to DRAM (Main Memory) or disks.
Q5. Locality of reference is the primary reason why:
- A. RAM size should be increased
- B. Cache memory improves performance
- C. Virtual memory is required
- D. Secondary storage is needed
View Answer & Explanation
Answer: B. Cache memory improves performance
Explanation: Cache relies on the fact that programs tend to access a small portion of their address space at any given time.
Q6. In which mapping technique is a block of main memory mapped to only one possible cache line?
- A. Direct Mapping
- B. Fully Associative Mapping
- C. Set-Associative Mapping
- D. Indirect Mapping
View Answer & Explanation
Answer: A. Direct Mapping
Explanation: Direct mapping uses a simple formula to assign each main memory block to exactly one cache location.
Q7. What happens to the “Hit Ratio” if the cache size is increased?
- A. It decreases
- B. It remains constant
- C. It generally increases
- D. It becomes zero
View Answer & Explanation
Answer: C. It generally increases
Explanation: A larger cache can hold more blocks, increasing the probability that the required data is present.
Q8. The “Miss Penalty” refers to the time taken to:
- A. Search the cache
- B. Access the CPU registers
- C. Replace a block in cache with one from main memory
- D. Write data to the cache
View Answer & Explanation
Answer: C. Replace a block in cache with one from main memory
Explanation: It is the additional time required to fetch data from a slower memory level after a cache miss.
Q9. Which memory is generally built from SRAM (Static RAM) chips?
- A. Main Memory
- B. Cache Memory
- C. Magnetic Tape
- D. BIOS ROM
View Answer & Explanation
Answer: B. Cache Memory
Explanation: SRAM is faster and more expensive than DRAM, making it ideal for cache memory.
Q10. The process of updating main memory whenever a cache write occurs is called:
- A. Write-back
- B. Write-through
- C. Write-around
- D. Direct write
View Answer & Explanation
Answer: B. Write-through
Explanation: Write-through ensures data consistency by updating both the cache and main memory simultaneously.
Q11. Which cache replacement policy replaces the block that has not been used for the longest period of time?
- A. FIFO
- B. LIFO
- C. LRU (Least Recently Used)
- D. Random
View Answer & Explanation
Answer: C. LRU (Least Recently Used)
Explanation: LRU assumes that data not accessed recently is unlikely to be accessed in the near future.
Q12. If the cache access time is 10ns and main memory access time is 100ns, with a hit ratio of 0.9, what is the average access time?
- A. 110ns
- B. 90ns
- C. 19ns
- D. 20ns
View Answer & Explanation
Answer: C. 19ns
Explanation: Average time = (0.9 × 10) + (0.1 × 100) = 9 + 10 = 19ns.
Q13. Which of the following is NOT a type of cache?
- A. L1 Cache
- B. L2 Cache
- C. L3 Cache
- D. L5 Cache
View Answer & Explanation
Answer: D. L5 Cache
Explanation: Standard architectures typically use L1, L2, and sometimes L3 cache levels.
Q14. Spatial Locality refers to:
- A. Accessing the same instruction repeatedly
- B. Accessing memory locations with addresses near each other
- C. Accessing different disks simultaneously
- D. Accessing the same register
View Answer & Explanation
Answer: B. Accessing memory locations with addresses near each other
Explanation: Spatial locality suggests that if a location is accessed, its neighboring memory locations are likely to be accessed soon.
Q15. A “Dirty Bit” is used in which write policy?
- A. Write-through
- B. Write-back
- C. No-write-allocate
- D. Write-around
View Answer & Explanation
Answer: B. Write-back
Explanation: The dirty bit tracks whether a cache block has been modified and must be written back to main memory before replacement.
Conclusion
These Cache Memory MCQ questions help strengthen important concepts of Computer Organization and Architecture (COA) such as cache mapping techniques, locality of reference, cache replacement policies, write policies, and cache performance calculations. These topics are frequently asked in exams like GATE, IBPS IT Officer, university semester examinations, and other technical competitive exams.
For detailed theory and better understanding of concepts, refer to Cache Memory in Computer Organization.