what is a CD-ROM technically speaking?
It is a round, flat piece of plastic, 120 mm in diameter, with a spiral track on one side that contains small bumps detectable with a laser and a mirror. These bumps are used to model bits, and according to the ISO 9660 – the standard that defines the CD-ROM characteristics – these bits are grouped together in sectors of 2336 bytes, of which usually 2048 are available to the user. Sectors are played at a speed of 75 per second, giving a data rate of 1.2 Mbit/s. ISO 9660 says a lot more than this; it defines file structure, error correction codes and so on, but the important thing is that this piece of plastic can carry a little over 600 Mb of data that can be retrieved in a little over an hour. CD-ROM as a medium is physically identical to the audio CD that was introduced to the world market in 1984. The audio CD has been an unprecedented success in the consumer market. In fact, as far as I know only two products have wildly surpassed the (often very optimistic) prognoses made by Ameri
