Disk hardware emulation, was Re: Grandfather system RTE6/VM?

Oh for %deity's sake... I am sure it was regarded as a Good Thing (if not essential) that the emulator works with all controllers _without modification_. In other words, no separate MFM and RLL versions. In any case, do you know the exact encoding details of every ST506 controller ever made? I certainly don't, and I've repaired a heck of a lot of them. If you're going to go far enough to decode the MFM (or whatever) encoding, you might as well also recognise sectors, etc and just store the user data (and any filesystem pointers in the headers, etc). This is very efficient of emulator RAM, but it means you need a different emulator for each controller/system. And you need to know a lot about how the controller actually encodes the data. However, for udoing write precompensation, I am not conviced that you need to know details of the encoding. Precompensation is a kludge to correct for a magnetic effect on the disk. How the pulses in the bitstream are shifted should only depend on that bitstream, and not on the data in encodes or how it encodes it. Therefore it should be possible to undo it without knowing the encoding method. -tony