2. Briefly answer the following questions: A. What is the difference between computer architecture and computer organization? B. What are the two locality principles observed with respect to user programs? How are these principles exploited in computer design? C. What is virtual memory? Explain the need for virtual memory. D. What are the main differences between a multi-processor system and a multi-computer system? E. In a shared memory system, explain two schemes to maintain cache-coherence.