View Full Version : Apple II disk format

January 1st, 2008, 07:11 PM
Does anyone have a good primer on the Disk II data encoding scheme, Group Code Recording (GCR)?

I'm looking to archive my various Apple II floppies. I know PC disk controllers can't read them, but I have a Catweasel "universal" floppy controller. I hope to modify some of the software that comes with the card to read the Apple diskettes and need to understand the technical details around the actual physical disk format.


January 1st, 2008, 11:30 PM
You want to find a real or online copy of Beneath Apple DOS and/or Beneath Apple ProDOS. Here is a citation of some relevant bits for you: