[Coco] Challenge: identifying file type by sector of data

[Robert Gault]

Allen Huffman wrote:
>> On Jan 13, 2015, at 10:37 AM, Robert Gault <robert.gault at att.net> wrote:
>> What is wrong with the "bad" directory sector? It won't read? It can be read but is trashed? Can you make an image of one of these bad disks such that the "bad" sector content is the same as the real disk?
>> If you can make an image that is identical to the "bad" disk, send it to me.
>
> ?IO ERROR ... can't read the sectors. I have about two dozen or so disks with errors (some went bad while I looked at them; should have done the backup first but was looking to see what was on them to know what to name the .dsk image). Most disks are things I hope others have (games, etc.) but some are BBS buffer saves and the like.
>
> 		-- Allen
>
>

Allen,

If these are 5.25" disks, what frequently goes wrong is that the sleeve gets 
squashed such that the friction of the sleeve on the disk both slows down the 
disk and can generate enough heat to erase the disk.
If you break the welds on the sleeve and spread all the edges, you can get these 
disks to work normally assuming the data is still there. You would need to 
remove the disk from the sleeve while spreading the edges. MAKE SURE YOU DO NOT 
FLIP THE DISK RELATIVE TO THE SLEEVE when you return it. The sides MUST match!

Now if it is just an rpm problem, you can adjust the drive using the strobe. I 
have a software program that will measure the rpm for you so an adjustment can 
be made more easily.

Robert