Ultimate FDC? (Was: IBM 6360 - Filesystem(ish) info?

Paul Koning paulkoning at comcast.net
Tue Feb 19 19:10:22 CST 2019

> On Feb 19, 2019, at 8:00 PM, Fred Cisin via cctalk <cctalk at classiccmp.org> wrote:
> On Tue, 19 Feb 2019, Fred Cisin via cctalk wrote:
>> As I see it, flux transition hardware COULD be all that is needed for hardware.  Emulation of FDC could be done in software with flux transition hardware.
> That should read flux transition plus appropriate control signals for the drive.  Seeking tracks, turn on the drives R/W circuitry, etc.
> Flux transition ITSELF is just making sense out of the pulses on the track.

Rather than flux transitions, flux levels would seem even better.  If the flux levels are sliced and reduced to square waves, you've lost a bunch of information that could have helped recover marginal data.

I' reminded of the Bordynuik tape reading machine that uses an MR head.  Capturing analog flux levels at, say, 10x the nominal flux change density means all the rest is simply digital signal processing.  That can be done in real time if you must, but much more easily in post processing using whatever tools and languages you like.


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