1. In segmentation, memory is divided into:
Correct Answer: b) Variable-size blocks
Explanation: Segmentation divides memory into variable-sized segments that correspond to logical units of a program (functions, arrays, etc.).
2. Segmentation allows:
Correct Answer: a) Logical division of a program
Explanation: Segmentation provides a logical view of memory by dividing programs into meaningful units like functions, arrays, or data structures.
3. The mapping between segment and physical address is stored in:
Correct Answer: b) Segment Table
Explanation: The segment table contains base addresses and lengths for each segment, used by the MMU to translate logical to physical addresses.
4. The main disadvantage of segmentation is:
Correct Answer: a) External fragmentation
Explanation: Variable-sized segments lead to external fragmentation as free memory becomes broken into small, non-contiguous pieces over time.
5. Which page replacement algorithm replaces the page that will not be used for the longest time?
Correct Answer: c) Optimal
Explanation: The Optimal algorithm (OPT) replaces the page that won't be used for the longest time in the future, though it's theoretical as it requires future knowledge.
6. The Belady's anomaly occurs in:
Correct Answer: a) FIFO
Explanation: Belady's anomaly is the counter-intuitive situation where increasing the number of page frames leads to more page faults in FIFO replacement.
7. The most commonly used page replacement algorithm is:
Correct Answer: b) LRU
Explanation: Least Recently Used (LRU) approximates optimal behavior by replacing the page that hasn't been used for the longest time, based on past references.
8. The LRU page replacement algorithm can be implemented using:
Correct Answer: d) All of the above
Explanation: LRU can be implemented with: (1) a stack that moves referenced pages to top, (2) a queue with reference bits, or (3) counters tracking last use timestamps.
9. Internal fragmentation occurs in:
Correct Answer: a) Paging
Explanation: Internal fragmentation occurs in paging when a process doesn't completely fill its last page, wasting the remaining space in that fixed-size frame.
10. External fragmentation occurs in:
Correct Answer: b) Segmentation
Explanation: External fragmentation happens in segmentation when free memory becomes divided into small, non-contiguous blocks that can't satisfy new requests.
11. Compaction is used to reduce:
Correct Answer: b) External fragmentation
Explanation: Compaction moves allocated memory blocks together to create larger contiguous free blocks, reducing external fragmentation (but is computationally expensive).
12. Which of the following does not suffer from external fragmentation?
Explanation: Paging eliminates external fragmentation because any page can be placed in any available frame, though it may cause internal fragmentation.
13. Virtual memory allows:
Correct Answer: a) Execution of programs larger than physical memory
Explanation: Virtual memory creates the illusion of a very large memory space by using disk storage to extend physical RAM, enabling execution of large programs.
14. Demand paging loads a page into memory only when:
Correct Answer: b) It is referenced
Explanation: Demand paging follows the "lazy loading" principle - pages are only loaded when they're actually needed (on first access), saving memory space.
15. A page fault occurs when:
Correct Answer: a) A page is not found in memory
Explanation: A page fault happens when a program accesses a page that's mapped in its address space but not currently loaded in physical memory.