zwsdotcom@gmail.com wrote: (snip, someone wrote)
As far as I'm aware, HD 3.5" mechanisms of all flavors (Mac, PC and other) _ALL_ use the HD hole to sense HD media and change the spindle
HD 3.5in run at 300RPM(*). It is HD 5.25in that run at 360RPM, and most do that even when reading/writing DD disks (at 300kb/s).
Actually once I'd posted this I realized I'd also forgotten that we were talking Apple drives - Apple's DD drives used variable speeds depending on where they were writing on the disk.
This group is next to comp.os.cpm in my news reader, and I wasn't even thinking about Apple DD disks at the time. The hole is needed to change the write current to match the disk, though. -- glen