13. A direct-mapped cache consists of 8 blocks. Byte-addressable main memory contains 4K blocks of 8 bytes each. Access time for the cache is 22ns, and the time required to fill a cache slot from main memory is 300ns. (This time allows us to determine that the block is missing and bring it into cache.) Assume that a request is always started in parallel to both cache and to main memory (so if it is not found in cache, we do not have to add this cache search time to the memory access). If a block is missing from cache, the entire block is brought into the cache and the access is restarted. Initially, the cache is empty.

1.

a) Show the main memory address format, which allows us to map addresses from main memory to cache. Be sure to include the fields as well as their sizes.

2.

b) Compute the hit ratio for a program that loops four times from addresses 0x0 to 0x43 in memory.

3.

c) Compute the effective access time for this program.