On May 30, 14:23, Roger Merchberger wrote: I have to say that this is not true. Plenty of DD disks are rated for 96 or 100 tpi. Furthermore, at the microscopic level, there is no difference between a DD disk sold for 96 tpi and one sold as 48 tpi. There might be more gross defects in older sold-as-48 tpi disk than in 96 tpi ones, I admit, and that could produce an error when narrow tracks are written. Nevertheless, the magnetic coercivity of the disk is the same in both cases. The difference between HD and DD is NOTHING to do with tracks per inch, it's ENTIRELY to do with the coercivity (which is a measure of the field strength required to produce the magentic polarisation used to write the data). -- Pete Peter Turnbull Network Manager University of York