examing disk platters was Re: Microscopes

On Sat, 20 Oct 2012, Paul Anderson wrote: "Disclosing fluid". It used to be used in magnetic audio and video recording for making "seamless" splices, by making the signal visible to be able to line up the diagonal (helical) scan lines. Monte made some of his own out of finely ground rust! I don't know what he used as a medium, probably a light oil. Floppy disks (48tpi and 96tpi) are 1/2mm or 1/4mm trqck to traqck spacing, and that was very readily visible. Individual bits along a track will require being able to resolve a bit better than 1/20 degree of rotational position. Way too tedious to manually examine the bits and manually decode them, unless you have a source of extremely cheap labor, such as grad students or third world workers. If you can get a clear image, then the software involved to analyze the flux transitions should be reaily do-able. Think polar coordinates, incrementing rotation to get the raw flux transition stream of a track, followed by software quite similar to what cat-weasel, disc-ferret, and/or any other flux-transition board uses. -- Grumpy Ol' Fred cisin at xenosoft.com