All cache (and in fact, memory as well) used to be single-cycle. Why aren't they any more? Because the speed of light doesn't allow it. Multi-cycle cache/memo

All cache (and in fact, memory as well) used to be single-cycle. Why aren't they any more? Because the speed of light doesn't allow it. Multi-cycle cache/memory latency and the cache hierarchy it implies is a result of being bound by the speed of light.