Jake Anderson wrote:
> Sounds like you might be well served to "re-engineer" the reading 
> mechanism for the disk itself if your going to all that effort anyway. I 
> imagine that modern amps and D/A converters and the like would be loads 
> better than something your going to find in an 8.5" fdd drive. Perhaps 
> even to the point of making up a magnetic scanner based on a cd drive or 
> some such. You should be able to get lots more information about what a 
> particular bit is sposed to be then?

I'm not interested in it from a data recovery aspect, I'm interested in it 
from a data archiving aspect. A solution for the whole machine-but-no-disks 
situation, basically. Then you have a binary disc image that can be emailed, 
FTP'd, Rapidshared and what not, and restored to a disc by someone closer to 
the person that needs the disc.

In any case, the important bits of information are:
   1) Is there a flux transition there?
and
   2) How long was it since the last flux transition?

With that, you can then decode the data (with a simple-ish MFM decoder) and 
then work on decoding the low-level structures (inter-sector gap, CRCs...) 
which would leave you with the actual data.

The question is not so much "what was the value of that bit?", but more "how 
long was it since the last bit?". If you know that, and you can eliminate 
spurious transitions, you can decode the data.
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