Where did the patent term come from?
Tyler Cowen has an interesting post up, What determined the playing length of an audio CD? Turns out Sony wanted a smaller diameter CD at first, but soon settled on a 120mm diameter so that the 74 minute version of Beethoven’s Ninth Symphony (the favorite piece of a Sony VP’s wife) could fit on a single CD. Interesting story, but the 74 minute length, and corresponding physical diameter of the CD, is not really arbitrary.