Best reference for low level Atari disk formats and protection?

[ianoid]

I need a reference for nibble level reading of Atari disks and Atari DOS. If anyone can recommend one, whether it’s a book or a magazine article,I’d love to track it down. Or if you have a strong understanding of low level Atari disk drive stuff, drop me a note, I need to pick your brain a little bit.

 

This is for a disk archival project. 

 

Thanks!

[Rybags]

Stock drives don't allow running user code like the C= 1541.  Many aftermarket upgrades such as Happy do though.

 

Dos is irrelevant here - it's just the filing system and copy protection is at a lower level.  Additionally most Atari games don't use a Dos file structure.

There's plenty of stuff that upgrades can't copy.  In the modern day the likes of Kryoflux and Catweasel have been used, which is generally copying disks without regard to format by just keeping a record of the flux transitions at a high resolution to allow later recreation.

[ianoid]

The goal is to both image unprotected disks with Atari DOS (and potentially other popular DOSes) with validation of files, and to flux image all disks with validation of nibbles. Information about protection schemes and any exotic nibble schemes would be really helpful for the software validation. This is for the Applesauce disk imaging project. 

 

As I understand it, Kryoflux and Catweasel can flux any disk, without much regard for the validity of the data. I’m referring to disk damage or other disk errors. The Applesauce software is in ongoing development to do this. I’m just trying to find some resources for the developer. 

[E474]

Hi,

 

   I think the Archiver/Editor manual has some information on disk protection. There is some info on programming a Happy drive in the first 5 issues of Atari Magazin 1987 (in German), I think the example code includes examples showing how to use the Floppy Disk Controller directly, there is also the data sheet for the FDC, which I think is a WD2793 which I think has some info on how data is organised on a track. Also, you might want to look at the ATX specs, as that will give you an idea of what a flux image can be converted to.

 

   Are you planning on writing code that will actually run on an 8-bit Atari?

 

   Hope this helps!