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

[Robert Gault]

Allen Huffman wrote:
>> On Jan 13, 2015, at 2:06 PM, Robert Gault <robert.gault at att.net> wrote:
>> 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!
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> Are you meaning I could take the disc out of the sleeve and it might let me read the one bad sector? Ditto on other disks?
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>> 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.
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> Wow. That takes me back. I believe OS-9 Level 1 had a speed test on its boot disk, didn’t it?
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> 		— Allen
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If the disk is bad, you probably are out of luck. If the sleeve is binding, 
removing the disk and spreading the edges of the sleeve and then returning the 
disk to the sleeve, will reduce the friction and the disk MAY be readable.

If one or more sectors are damaged, the disk might be readable with the proper 
software. Keep in mind that some copyright schemes removed the data address mark 
from some sectors so a disk could not be backed up. A program like my Colorzap 
can restore DAMs to sectors.

Robert