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What architectures are (1) not incredibly niche, (2) have practical hardware in the wild, and (3) are so divergent from Von Neumann as to dramatically change th

• SAI_Peregrinus 9y ago
  FPGAs & CPLDs. Of course those aren't really CPUs to be programmed with software, they're another level of abstraction down. But they're pretty common and hardware description languages are vastly different from C. The inherent massive parallelism of FPGAs & the resulting combinatorial-by-default (sequential only when explicitly declared) languages requires a very different way of thinking.
• hoosieree 9y ago
  I was thinking bigger than a single CPU. For example: 2 computers (even if they're both Von Neumann machines) together comprise a non-Von Neumann system. Some single-device examples are pretty common, like GPUs and NICs. But what I really had in mind are systems that communicate by passing messages. Distributed systems certainly have an "architecture", but it spans many machines; and communication occurs via messages (RDMA being an exception). Even modern CPUs contain non-Von Neumann features like multiple cores, pipelines, and out-of-order execution, so the line gets blurry. To a large extent modern CPUs enable C-style programming with a lot of contrivances to hide the fact that they're not quite Von Neumann anymore. Dealing with the different architecture becomes the compiler's job. "Thinking in C" hinges on the idea that the size of memory is several orders of magnitude larger than the number of cores, and that you can only modify these words one at a time.