In a quad-core system using the MESI protocol, Processor A reads a line (Exclusive state). Processor B then reads the same line. If Processor A then writes to that line, what is the sequence of state transitions?
Explanation: When B reads the line A has in 'E' state, both move to 'Shared' (S). When A wants to write, it must upgrade to 'Modified' (M) by broadcasting an invalidation to all other 'Shared' holders (Processor B), moving B's copy to 'Invalid' (I).
