With all deference to the real collectors, I don't see the objective here. The thing should be NEC 765 compatible? Why? What about non-NEC-based sytems (e.g. the bulk of CP/M and countless other systems that don't use an LSI controller)? Or those systems that permanently already have a controller installed? And you know--not all systems used disks with standard-length (i.e. power of 2) sectors. (e.g. Zilog MCZ) or oddball addressing schemes? How about those old Apple II floppy protection that manipulated the positioner current to land the head *between* tracks?
And other than *reading* the things once, why are we trying to fool with decaying doughnuts of rusty dust? Sample the rusty rings, stash the data away for use by analysis. If amenable to emulation, write a floppy *drive* emulator to match. Otherwise, you've got the data. My take on this subject only--but then, I'm mostly concerned about *reading* dusty rust and preserving the information for future reference, not recreating the original scenario. A NEC 765 is pretty limited in what it can do, in the firmament of floppy formats--I don't even know how to tell it to deal with, say, 132-byte sectors. Thanks for allowing me to spout my nonsense. --Chuck