5.25" PC drives

[oggie]

Basically, most every type of 5.25" disk drive works.  I am not sure if backside imaging works with that drive, but most drives have jumpers for ignoring the index pulse and still allow reading.

On standard double sided disks/drives, the tracks of the second side are at a slight physical offset. This has to do with the way double sided drive head assemblies work - you can't just put both heads precisely right on top of each other.

The problem comes in that many single sided disks, especially in Apple II and C64, were used as "flippy" disks. Instead of having two heads, users used both sides by manually flipping the disk over. These disks do not have that offset. So you can't just read the back side of a "flippy disk" with the second head of a normal drive.

The problem here is that many IBM PC style drives also look for an Index hole. Systems like the Apple II ignored the index holes. If you flip that disk over like the Apple II users did, the IBM PC style drive will not find an index (unless someone punched a second hole) and may refuse to ever enter a "ready" state, preventing reading or writing.

Interesting. so if you use a double sided drive (panasonic ju-475 for example) to read a c64 disk, it can, in theory read both sides at once, correct? but if you do, the back side will be incorrect due to this offset.  So if you `flippy mod` the drive, it will allow you to copy both side of a c64 disk without having to physically rotate the disk in the drive and therefore create 1 image for both sides at once. But if you don't mod the drive, you will have to manually flip the disk over and create two images?