Reply 20 of 27, by Battler
This is the first time I hear of 86Box supporting .HFE, now .MFM we do support, but the problem with the standard .MFM format is that it's inadequate - the amount of bitcells is rounded to the nearest byte so if the track wraps around in the middle of a sector, that sector is unusable, and all the data (RPM, etc.) is only stored once for the entire disk instead of per-track and per-side. I did create my own version of the .MFM format that addressed these problems and even submitted it to the developer of HxC but it never got accepted. He did begin working on .86F support instead but I'm not sure what state that's currently in.
However, none of the above emulators fully simulates the operation of FDC.
What exactly is not simulated by 86Box? It internally converts every inserted floppy image to a MFM (or FM)-encoded surface if it's not already one, and processes the data bit by bit, decoding the various address marks, etc. Though, of course, it's not perfect, so there may be edge cases where it returns the incorrect error.