5.25 floppies that read but don't write

On Thu, Aug 20, 2015 at 9:01 PM, dwight <dkelvey at hotmail.com> wrote: And beyond that, sometimes trying to format or write to a "360K" (48 TPI) disk in a "1.2M" (96 TPI) drive does appear to work, and may even appear to read reliably on the same drive, but it's *NEVER* going to be reliable to read it on an actual 48 TPI drive. The best case result is if you use a 96 TPI drive with a floppy that has NEVER been written (even at the factory), and format it and write at 48 TPI, that actually may read reliably on 48 TPI drives, because it doesn't have remnants of normal-width 48 TPI tracks. However, it's still not recommended for obvious reasons. Some people have claimed that they've been able to achieve the same effect by degaussing the floppy first, but when I experimented with that I found that even a supposedly high-power degaussing coil was pretty marginal for actually erasing floppy disks. It definitely would corrupt the data and render it unreadable, but it did NOT yield a truly erased disk.