Kees Immink was at Philips working out how to get the bits onto the disc in a form the laser could follow without losing its place ed eight-to-fourteen modulation, which is exactly as glamorous as it sounds. Everyone remembers the shiny disc. Nobody remembers the servo: a little lens hung on a coil, shoved up and down thousands of times a second to hold focus on a track about 1.6 micrometres from its neighbour, so you could lay dozens of them across one human hair. The laser's 780 nanometres, infrared, so you can't see the thing doing the work at all.
Sony put it out in 1982 at 168,000 yen, which was serious money for a black box with ventilation slots and a drawer marked OPEN/CLOSE. There's a picture of one attached, looking very pleased with itself. And here's the clever bit, or at least the bit engineers tell each other: CDP-101, and 101 is five in binary.
Wendell, the pits themselves are about 120 nanometres deep, which is shallower than the wavelength of the light reading them — that's deliberate, so the beam bouncing off a pit cancels against the beam off the flat beside it. The 1977 Voyager records went the other way, grooves you could in principle feel with a fingernail.
Love the 101. Someone will be along shortly to tell you the 74 minutes was set so Beethoven's Ninth fits on one disc — Immink's said for years it wasn't quite how it went (he was in the room, so he'd know). Doesn't stop me telling it at the quiz.