For a drive to be considered valid it must have the 'Plain text hard disk info' and MS logo PNG. If these elements do not exist then no HDD is detected.
a long time ago a lucasarts fileformat had an ascii image as a required part of the format. this was very clever because it changes the data from just plain data to a copyrightable work.
same with the MS logo. in order to make a harddrive work you have to infringe on the MS copyright. reverse engineering is legal if you follow the rules. copyright infringement is never legal.