This set of Memory Management MCQs covers advanced concepts of Operating System Memory Management, including inverted page tables, segmentation, effective access time, locality of reference, TLB concepts, page faults, thrashing, and virtual memory techniques. Useful for GATE, IBPS IT Officer, university semester exams, and technical interview preparation.
Topic: Operating System (Memory Management) | Set: 3
Difficulty: Hard to Medium | Total Questions: 15
Operating System Memory Management MCQs
Q1. In an “Inverted Page Table,” the number of entries is equal to:
A. The number of pages in virtual memory.
B. The number of frames in physical memory.
C. The number of processes running.
D. The size of the disk.
View Answer & Explanation
Answer: B
Explanation: Unlike standard page tables, an inverted page table has one entry for each physical frame in RAM, reducing memory overhead significantly.
Q2. Which field is NOT typically found in a Page Table Entry (PTE)?
A. Frame Number
B. Protection bits (R/W)
C. CPU Register values
D. Reference bit
View Answer & Explanation
Answer: C
Explanation: CPU register values are stored inside the Process Control Block (PCB), not in the page table entry.
Q3. What happens to the “Effective Access Time” as the page fault rate increases?
A. It decreases.
B. It remains constant.
C. It increases linearly.
D. It increases drastically.
View Answer & Explanation
Answer: D
Explanation: Since disk access during page faults is extremely slow compared to RAM, even a slight increase in page faults severely impacts performance.
Q4. “Pre-paging” is a technique used to:
A. Prevent fragmentation.
B. Reduce the high number of page faults during process startup.
C. Delete unused pages.
D. Speed up disk writes. View Answer & Explanation
View Answer & Explanation
Answer: B
Explanation: Pre-paging loads several pages before they are requested to reduce startup page faults.
Q5. Hashed Page Tables are particularly useful for:
A. Small address spaces (16-bit).
B. Fixed partitioning.
C. Sparse address spaces larger than 32 bits.
D. Systems without virtual memory.
View Answer & Explanation
Answer: C
Explanation: Hashed page tables efficiently support large sparse virtual address spaces, especially in 64-bit systems.
Q6. In a Segmented system, a logical address consists of:
A. <page, offset>
B. <segment-number, offset>
C. <frame, offset>
D. <base, limit>
View Answer & Explanation
Answer: B
Explanation: The segment number selects the segment table entry, while the offset identifies the location within the segment.
Q7. A “Trap” is used in memory management to:
A. Catch a virus.
B. Signal the OS that a page fault or protection violation occurred.
C. Terminate a process.
D. Clear the TLB.
View Answer & Explanation
Answer: B
Explanation: A trap transfers control from the user process to the operating system kernel during exceptional events.
Q8. “Proportional Allocation” of frames means:
A. Every process gets 10 frames.
B. Frames are given based on process priority.
C. Frames are given according to process size.
D. Frames are given to the first process that asks.
View Answer & Explanation
Answer: C
Explanation: Larger processes receive more frames relative to their memory requirements.
Q9. The “Reference Bit” is primarily used by:
A. FIFO
B. Optimal
C. LRU-approximation algorithms
D. Segmentation
View Answer & Explanation
Answer: C
Explanation: Reference bits help approximate recently used pages without maintaining expensive exact tracking structures.
Q10. Memory protection in a paged system is usually accomplished by:
A. A physical lock on the RAM.
B. Protection bits associated with each frame in the page table.
C. Encrypting the memory.
D. Using a limit register for every page.
View Answer & Explanation
Answer: B
Explanation: Read, write, and execute permission bits control access rights for memory pages.
Q11. What is the primary cause of Thrashing?
A. Too much RAM.
B. High degree of multiprogramming with insufficient frames.
C. Fast CPU.
D. Using the LRU algorithm.
View Answer & Explanation
Answer: B
Explanation: Thrashing occurs when the operating system spends more time swapping pages than executing processes.
Q12. “Locality of Reference” refers to:
A. Data stored on the same disk.
B. Processes repeatedly accessing a small set of pages.
C. Using the same variable name.
D. CPU proximity to RAM.
View Answer & Explanation
Answer: B
Explanation: Programs tend to repeatedly access nearby instructions and data during execution.
Q13. The “Effective Access Time” formula with TLB is:
A. Hit Ratio × (TLB access) + Miss Ratio × (Memory access)
B. Hit Ratio × (TLB + Memory) + Miss Ratio × (TLB + 2 × Memory)
C. Memory × 2
D. TLB + Memory
View Answer & Explanation
Answer: B
Explanation: A TLB miss requires one access for the page table and another for the actual memory location.
Q14. If the page size is increased, what is the likely effect on internal fragmentation?
A. It decreases.
B. It increases.
C. It stays the same.
D. It disappears.
View Answer & Explanation
Answer: B
Explanation: Larger pages increase wasted unused space inside partially filled pages.
Q15. “Shared Pages” must be:
A. Stored in different physical frames.
B. Read-only to ensure consistency between processes.
C. Executable only.
D. Dynamic.
View Answer & Explanation
Answer: B
Explanation: Shared pages are generally read-only to prevent one process from modifying code used by another process.
Conclusion
These Operating System Memory Management MCQ questions covered advanced concepts such as paging, segmentation, TLB, page replacement, thrashing, effective access time, and virtual memory management.
Practicing these questions regularly is highly beneficial for GATE CS, university semester exams, IBPS IT Officer, GATE, and technical interview preparation.
For detailed theory, refer to Operating System Memory Management .