2. A computer uses virtual memory (implemented as paging). It has a cache, main memory and a hard disk. Cache access involves 5 nslookup and 10 ns transfer time of a word into a register. Main memory access involves 15 ns lookup and 80 ns data transfer time into a register (this is done in parallel with transferring the data into the cache). Accessing the hard disk involves 4 ms seek time and 6 ms transfer time into main memory. The cache hit ratio is 04. In the case of a cache miss, the probability that the word is in the main memory is 0.7. (a) Describe the necessary steps and compute the load time when the referenced word is in the cache, [2 marks) in main memory (but not in the cache), [3 marks] on the hard disk (but not in main memory). (5 marks) (b) Compute the average load time. (5 marks]