Linards Ticmanis wrote:
Michael J. Mahon wrote:And there is no way of knowing how to interpret the data without running or simulating the Apple II code that reads the disk. It could, for example, read nibbles until it encounters a magic nibble sequence, then seek forward two phases in a precise number of cycles, then continue reading nibbles from the new location.Hello Michael, If you don't stop the disk during the whole read process, and sample at a fixed rate, wouldn't your samples automatically be associated with a (relative) rotational angle, with limited accuracy to be sure, but no more limited than what any reliable copy protection scheme could rely on? Or am I missing something here?
No, within the limits of speed fluctuations within a rotation (which should be within the tolerances allowed for by the program anyway), timing is a good reference. It *does* need to be referenced to a fixed point on the disk, like T0, S0, since speed often drifts over several rotations. The point I was making is that the nibbles a program reads after a synchronized seek may not be a part of any "normal" data structure on a track, so all tracks must be saved regardless of any apparent structure or lack of it. -michael NadaNet networking for Apple II computers! Home page: http://members.aol.com/MJMahon/ "The wastebasket is our most important design tool--and it's seriously underused."