I've been told by chip designers that chip-crossings are on the order of 5-10 cycles these days. This is for data; they can arrange faster crossings for some si

I've been told by chip designers that chip-crossings are on the order of 5-10 cycles these days. This is for data; they can arrange faster crossings for some signals, such as clocks, but they don't like doing this. GPUs are getting really interesting. It's not general purpose yet -- you still have to worry a lot about contention and memory bandwidth -- but you can do a jaw-dropping amount of computation in a second on a recent GPU. One thing Knuth doesn't mention is that he may not explicitly use that extra core on his workstation more than once a week for computation, but he /does/ use it for parallelism at the OS level, where it's helping reduce the latency of his interactions. I can definitely tell a single CPU box from a multicore box, given a couple of Emacs sessions.