What is the difference between a 74min and 80min CD? I was just recording to my scratch CD and noticed that it had passed the 645Mb limit of a 74min CD, therefore it must be 80min. I base a CD's capacity on how wide the unwritten stripe is, but I wondered how the CD Writer knows the difference? I assume the CDs are the same physical size, and the laser diode tracks and pulses at the same rate and the disk spins at the same speed. So there must be something else clever, like a small gnome that twiddles a small screw in the CD writer. Any clever people out there who can confirm my gnome theory, preferably with photographs; or alternatively any crack pots with ridiculous off the wall theories about how it could be done with technology?