jan 1, 1958 - Laserdisc
The first commercially available laserdisc system was available on the market late in 1978 and wee 11.81 inches in diameter. The discs could have up to 60 minutes of video/audio on each side. It was invented by David Paul Gregg. The original price was around $35-$40.
Added to timeline:
Some early storage devices, to more up-to-date ones.