Did you know

1. The data transfer rate of a DVD drive is given in multiples of 1350 kB/s, which means that a drive with 16x speed designation allows a data transfer rate of 16 × 1350 = 21600 kB/s (21.09 MB/s). As CD drive speeds are given in multiples of 150 kB/s, one DVD "speed" equals nine CD "speeds", so an 8x DVD drive should have a data transfer rate similar to that of a 72x CD drive. In physical rotation terms (spins per second), one DVD "speed" equals three CD "speeds", so an 8x DVD drive has the same rotational speed as 24x CD drive.

2. There is a 15-mm hole in the centre of the disc, usually used by some form of clamp or clip device within the player to hold it in place and allow it to be rotated by a motor. The diameter of the hole is the same as that of a former Dutch 10-cent coin. Philips engineers at the time used the coin to determine the size of the hole, and the coin fits inside the hole perfectly.