So the theory is that MSDOS tried to detect if a bootsector contained executable 68k code, because if it did, the BPB was valid and could be used to locate the FAT(s) and the master directory?<p>That's triply dumb, because of the typo noted in the article, and also because executable Atari ST bootsectors had a checksum that should be computed instead of silly heuristics, but most importantly because most Atari ST disks had no executable bootsector, but the entries concerning disk layout were still valid.<p>It sounds exactly like the fractal of incompetence Microsoft would implement, and it would explain why we Atarians had to use disks formatted on a PC for data transfer, even though the formats were nominally the same. Funny to read about that, because back in the day, I thought the ST somehow formatted disks "wrong".