Consider a system with four processors: A$,$ B$,$ C$,$ and D$,$ where each processor has its own

dedicated cache memory, namely CA$,$ CB$,$ CC$,$ and CD$.$ The system uses MESI protocol to deal with

cache coherence.

Suppose processor B is accessing a certain memory write operation to memory line X$.$ Based on

the other processor$$s cache memory contents, few different scenarios may occur. Among these

scenarios, consider the following:

i$)$ Only CB has a copy of X$.$

ii$)$ CB has a copy of X in shared state.

iii$)$ Only Cc has a copy of X and the corresponding state of Cc$$s cache is

Modified.

iv$)$ No caches have a copy of X$.$

The above scenarios are independent of each other, that is$,$ the outcome of one scenario has no

effect on the other scenario. Analyse the above scenarios and identify:

$$ whether this is a cache hit or a cache miss?

$$ the changes made in the state of the caches in the initiating processor $($B$),$ the

responding processors $($if any$)$ and the memory contents $($if any$).$ Provide sufficient

details to support your answer.