"Parity is for farmers." -- Seymour Cray That's a famous quote that is hard to figure out. It was from some time in the 1960's. This was after his CDC 6600 was released (without parity) and before his CDC 7600 (which had parity). - Cray is the most famous designer of supercomputers. - "parity" has two meanings in this quote - the main meaning is: extra memory bits to detect some memory or bus failures (ones with an odd number of bit-flips) - the mainstream belief was that parity checking was really useful to detect when things have gone wrong. In that era, lots of things went wrong. - my interpretation is that Cray just didn't want to waste circuitry, ferrite cores, and speed on parity bits. Why speed? Because it would surely affect fan-out or fan-in of some circuits on the critical path of his processor, which would in turn affect how fast they could be driven. Other designers were more humble: they liked to know if the results were corrupt. Cray advocated running test programs once in a while to see if the processor was still working. This would actually reduce the computation power available less than parity checking. - I'm pretty sure that every current serious supercomputer uses not just parity but ECC. This may not be the case for GPU computing. - "parity" was also a term used to describe certain features of US farm subsidies of that era. This (possibly fringe) paper <http://c457332.r32.cf2.rackcdn.com/pdf/the-freeman/0604Folsom.pdf> says: Two concepts in the AAA are fascinating. First is the idea that because farmers overproduce some crops the government ought to pay them not to grow on part of their land. Second is the idea of "parity," that farmers ought to be protected from falling prices by fixing them so that they were comparable to the purchasing power of their crop in the excellent years 1909-14. Note that AAA was the US Agricultural Adjustment Act of 1933 or 1938 <https://en.wikipedia.org/wiki/Agricultural_Adjustment_Act> This seems to have been part of Roosevelt's New Deal. So: does this famous quote win the obscurity competition? "Farmers buy computers too" -- Seymour Cray, after CDC 7600 was introduced. If you want to know more about Cray, here's a slide deck from Gordon Bell (a great computer architect, practical and academic). <http://research.microsoft.com/en-us/um/people/gbell/craytalk/> It's from a talk given shortly after Cray's death. Funny point: the abstract calls Cray "the ultimate "tall, thin man"*." but the notes on slide three call him the penultimate one. I wonder who the ultimate one is if the notes are correct.