However, because there is physical contact between the stylus and the disc, both the grooves and the stylus can wear over time, similarly to vinyl records. This system was dubbed ‘Capacitance Electronic Disc’ or CED. Which was a shame, really, because CED was truly a viable alternative to nothing, and much better than broadcast television with its multitude of commercials. But key features of LaserDisc, such as random access seeking (used in games such as Dragon’s Lair) and the robustness of the discs were absent, and this strategy backfired, framing CED as an inferior ‘copycat’ and discrediting it in the minds of consumers, who elected instead to buy nothing and wait until they could afford a VCR. RCA had hoped to capitalise on the exotic public perception of disc-based video by offering a more affordable alternative. While LaserDisc used a laser to read discs, which meant there was no contact with them and they could theoretically last forever, in the 1970s and early 1980s they were super-expensive and thus adoption was limited to only true videophiles. The capacitance (that is, the amount of electrical charge necessary for current to pass from the disc to the electrode) is measured, and because this varies based on the depth of the stylus in the groove (the higher it is the more charge is required) a signal can be reconstructed. A diamond stylus sits in the groove, a metal electrode attached to it. The video signal is stored on the disc by varying the depth of the grooves to correspond to the waveform of a frequency-modulated (FM) video signal – similar to a broadcast television signal. The system worked by making the disc conductive – that is, electricity could pass through it. But by 1972 the team had produced a prototype disc system capable of holding 10 minutes of colour video.

RCA first began researching a method of recording video on to a disc in 1964, however they didn’t devote a lot of resources to it and with only four people working on it development was slow. While Asian manufacturers were feverishly working on perfecting videotape, American RCA was working on a videodisc system – not a laserdisc system, which did not contact the surface of the disc, but instead a system similar to a phonograph record, where a needle sat in a groove carved into the disc.

Ced betn1