We have a $2-$way set associative cache and we use the recently used bit scheme to

implement LRU for a replacement strategy. Answer the following questions.

a$.$ We have an address that maps to line $12$ and the tag matches line $12$ of set $0.$ What

happens with each set$$s used bit?

b$.$ We have an address that maps to line $28$ and matches neither tag. How do we decide

which of the two sets to discard?

c$.$ We decide to expand the $2-$way set associative cache to a $4-$way set associative cache.

We can$$t still use the recently used bit scheme to implement LRU, why not?

d$.$ How could we implement LRU for the $4-$way set associative cache in place of a single

used bit and why would we not want to do this?