I know the real story :
IBM wanted an OS for their new system, the forthcoming original IBM-PC.
They asked both Bill Gates and the chief of Digital Research.
The god man wasn't met, instead his wife, and the IBM people only wanted to speak to the man (sorry, Ive forgot his name), buit had to leave, because he wasn't there.
So the story goes that DR was not involved in that.
Instead, Gates agreed, and BOUGHT an already existing OS called "QDOS" ("Quick-and-dirty-Disc-Operating-System" was it's title, as far as I haver read it), and modelled it into MS-DOS, selling it with the Original IBM PC.
DR-DOS was created after that, and MS did everything to hinter it (it is proved that Microsoft included routines into Windows 3.1 in order to let it not work together with DR-DOS, then).
That's the real story.
