MFM floppy disk write precompensation

On Fri, Aug 09, 2013 at 04:00:31PM -0700, Glen Slick wrote: I was wondering the same thing (I too am working on floppy write code, but it's currently back-burnered by my day job). I've heard 43 thrown around but I wonder if it's confusing two ideas. I'm not a doctor but I would think that write precomp should be more of a progressive thing, as the track #s go up (so the total track circumference goes down and the bits are squished closer together). But maybe I'm worrying too much -- the data tracks never get that close to (or far from) the center so it's possible that two (or even one?) precomp offset(s) work for the whole disk. Certainly FDCs don't normally bother knowing anything specific about the drive and/or medium so they aren't optimizing. John Wilson D Bit