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

[Gene Heskett]

On Tuesday, January 13, 2015 01:15:15 PM Allen Huffman did opine
And Gene did reply:
> > 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

If it failed while reading them, 2 things. 1, clean the drives heads. 2, 
store the disks in a sealed container with as many bags of silica jell 
you can muster up and bake dry in the microwave in it, for at least a 
week.  Wet magnetic media is both soft, and abrasive as can be. The key 
is as low a temp storage, as dry as you can keep them. For long term 
storage a closet on an outside wall is ideal so you can stick a tiny 
airconditioner in the wall, one that runs nearly non-stop because its too 
small, is ideal. Target 50F temps, and the ac will keep the humidity 
under 30%.  An old dehumidifier, dismantled and its hot coils moved 
outside, is ideal for a small closet.  Run its cold coil drain outside 
too.

From my broadcast experiences, VCR headwheels, normally rated for 
500-750, maybe 1000 hours, will last 10,000+ hours when they are working 
with cold, dry tape.  Disk media should be the same.  My hard walled 
basement is both heated and air conditioned and has 2 dehumidifiers 
running 24/7 because the 40 year+ old walls seep water badly when it has 
rained and the clay based soil is saturated.  And I have not had any old 
disks I cannot read yet.  That knocking sound? Yup. Me, knocking on wood.

Cheers, Gene Heskett
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