Ian Oliver wrote:
Will fdrawcmd let me ignore CRCs and just got whatever is there?
Hmmm, some sniffing around suggests that these disks have a proprietary format.
What system were they from? That might be helpful to list readers (or yield someone with a working system that can read them "natively")
The first cylinder is normal, but after that, the next 21 cylinders don't even have a sector 0.
I seem to recall CP/M systems where the first cylinder was in a generic format (and contained driver code for a more complex floppy controller) with the remaining cylinders being in a 'better' format that the controller could still read) - I suspect that 'trick' was used by various systems outside of the CP/M world, too. Perhaps you're seeing something like that? Does looking at the physical data fetched from the first cylinder give any clues? Often (but by no means always!) the first cylinder data will contain useful data about the disk's layout and what's on it...
I suspect there are 14 sectors of non-standard sizes, so this is all going to be great fun.
Is there a chance that the disks are encrypted? I've seen that, too, with tweaks applied to sector headers - it can make reading on a 'alien' system rather interesting. (Sadly, I've also seen significantly-damaged disks throw up the kind of results you're seeing, with varying disk geometry, simply because the poor FDC's doing the best it can with mangled data) cheers Jules