So many memories. The "ultimate machine" (which was brought out and demonstrated from time to time while I was at the Labs) was built in collaboration with Ed Moore (he of Moore-model automata, who published "Dijkstra's algorithm" for shortest paths a year before Dijkstra) and (I believe) Dave Hagelbarger. Moore endowed the machine with a longevity property seldom remarked on: majority logic so that any electrical component can be removed without harming its observable behavior. Shannon moved to MIT from Bell Labs some weeks before I moved the other way, so I only met him much later when he visited the Unix room (an excuse, albeit weak, for this distant detour from TUHS). By that time Shannon was descending into Alzheimer's fog, but his wife who accompanied him was a memorably curious and perceptive visitor. I have wondered what role she may have played as a sounding board or more in Shannon's research. As a child, I used to ski on the 50-foot hill that was the lawn of the mansion that Shannon would buy when he moved to Massachusetts. We kids would ski down and climb back up. Not Shannon. He installed a chairlift. One house separated mine from the ski hill. It belonged to John Trump, another MIT prof who engineered the Van de Graaff generator into a commercial product for generating million-volt x-rays and, yes, was uncle of the Donald. John, as kind as he was bright, fortunately did not live to see the apotheosis of his wayward nephew. Doug > We lost Claude Shannon on this day in 2001. He was a mathematician, > electrical engineer, and cryptographer; he is regarded as the "father" of > information theory, and he pioneered digital circuit design. Amongst > other things he built a barbed-wire telegraph, the "Ultimate Machine" (it > reached up and switched itself off), a Roman numeral computer ("THROBAC"), > the Minivac 601 (a digital trainer), a Rubik's Cube solver, a mechanical > mouse that learned how to solve mazes, and outlined a chess program > (pre-Belle). He formulated the security mantra "The enemy knows the > system", and did top-secret work in WW-2 on crypto and fire-control > systems.