[Mannaggia l'America]

Gates had one with MS-DOS (Microsoft Disk Operating System). I think he wrote it himself, but I"m not sure. Gates held out for a royalty deal. IBM had no choice but to cave in.

Gates knew IBM was looking for an OS, so he bought the forerunner to MSDOS from a company called Seattle Computer Products. Their product was a CP/M clone for the 8086 CPU. Gates bought it from SCP for I think $75,000. Eventually Microsoft paid them $1 million to settle a lawsuit.

[Still Thinking]

Are you sure? I thought IBM was talking to Gary Kildall at the same time they were talking to Gates. Supposedly, they showed up at his house, Kildall was out, his wife wouldn’t sign an NDA, so Gates ended up getting first crack, and the rest is history.

[Myrddin]

The precursor of MSDOS wasn't much better than CP/M. Gates hired J. Gordon Letwin away from Heathkit where he authored most of HDOS (Heathkit DOS). Letwin incorporated the loadable device driver from HDOS into the new MSDOS to make it more flexible than CP/M. Microsoft also licensed System 7 UNIX from Western Electric. That became the baseline for their Xenix product on the Tandy/Radio Shack TRS-80 Model 16 (68000). Letwin incorporated the tree structured filesystem of UNIX into MSDOS, but bastardized the slash/backslash orientation to pretend it was "different".

I recognize much of the technology snitched from HDOS and UNIX as I've had full source code to both since 1980.