i) What is a TLB and what does it do? ii) Consider a memory system with a cache access time of 10ns and a memory access time of 200ns. If the effective access time is 10% greater than the cache access time, what is the hit ratio H ? iii) Consider a paging system with the page table stored in memory with memory reference takes 150 nanoseconds. 1) How long does a paged memory reference take? 2) For system with a two-level page table and no TLB, how long does it take to access a paged memory reference? 3) If we add TLBs, and 80 percent of all page-table references are found in the TLBs, what is the effective memory reference time? (Assume that finding a page-table entry in the TLBs takes zero time, if the entry is there.) 4) If we use a TLB that has a 90% hit rate, what is the effective memory reference time now