What is the average access time for a memory system with 90% hit rate, cache access time 5ns, and main memory access time 50ns?
Q1. What is the average access time for a memory system with 90% hit rate, cache access time 5ns, and main memory access time 50ns?
Answer: 9.5ns
Explanation: Average access time = (hit rate * cache access time) + ((1 - hit rate) * (cache access time + main memory access time)) = (0.9 * 5) + (0.1 * (5 + 50)) = 4.5 + 5.5 = 9.5 + 0 = 9.5ns, simplified as 0.9*5 + 0.1*55.