"The way I heard the story of MSDOS was that Bill has BSed IBM that he made a working OS but when they gave him the contract he had to run down to the local UNI to see if they had anything running on 8086."
Not quite. IBM were going to use CP/M but couldn't agree with license condtions with DR.
Gates went to Seattle Computing and bought "Quick & Dirty DOS" for US $50,000; and went to IBM with it. The designer, Tim Paterson, was later hired by Micro-Soft (sic).
Seattle Computing later said in court that Gates hadn't mentioned IBM to them during their talks to keep the price down, and MS paid an extra US $1 million.
As the license wasn't exclusive to IBM, MS were able to sell elsewhere (PC-DOS & MS-DOS).