This document discusses high performance computing and topics related to cache coherence and vector processing. It provides an overview of cache coherence approaches including write-back and write-through implementations. It also describes hardware-based cache coherence solutions like directory and snoopy protocols. The directory protocol uses a centralized controller while snoopy protocol relies on broadcast messages. Specific cache coherence protocols like MESI and write-invalidate are explained. Vector processing and Amdahl's law on parallel programming speedup are also briefly mentioned.