These architectures can be used as message switches, routers and small multiprocessor parallel architectures. Busy-waiting is effective for both uniprocessor and multiprocessor systems. Coherence protocols apply cache coherence in multiprocessor systems. The term "multiprocessor" can be confused with the term "multiprocessing". Tightly coupled multiprocessor systems contain multiple CPUs that are connected at the bus level. Another use for HyperTransport is as an interconnect for NUMA multiprocessor computers. Multics supported multiple CPUs; it was one of the earliest multiprocessor systems. Multiprocessor SoCs have more than one processor core by definition. Cointegration of multiprocessor applications provides flexibility in network architecture design. The network topology is a key factor in determining how the multiprocessor machine scales. The terminal implements a client-server architecture with the server running on a multiprocessor Unix platform. Stockfish can use up to 512 CPU threads in multiprocessor systems. Most multiprocessor systems today use an SMP architecture. The Kepler architecture employs a new Streaming Multiprocessor Architecture called SMX. A "Streaming Multiprocessor" corresponds to AMD's Compute Unit.