@tubetime I have loved this thread. While I've got into bit-level understanding of floppies before, hard disks have always been mysterious black boxes to me, and while at a logical level I understood they'd be something like this, this actual reversing has been a great way to remind myself they're not magic! Thanks.
@sgf thanks! yes, it's easier to understand the older drives, but there's a steady, linear progression from then to modern drives.