> That relationship had been established in late 1982. Back then, Gates had contacted Canion and asked, with some concern, if Compaq was trying to get into the operating system business. Surprised, Canion denied it. Gates told him that Microsoft was hearing worrying reports from the dealer network. People were buying copies of Compaq DOS, rather than Microsoft DOS, without buying a Compaq PC.

> Both men knew why: Microsoft DOS had never been a true copy of PC DOS, as Gates had admitted to Canion during the development of Compaq’s first machine. The differences had only increased over time, as Microsoft’s deal with IBM prohibited the same developers working on both versions. Compaq had made its own version of DOS since the beginning. With its singular focus on 100 percent compatibility, the result was a product that was more compatible with PC DOS than Microsoft’s own product.

> Word was spreading among computer buyers that Compaq DOS was better. Even people who owned other PC clones were choosing to buy that instead of Microsoft’s own public version. This could have created friction between Compaq and Microsoft. Instead, Canion did something extraordinary. Compaq withdrew Compaq DOS from sale unless it was specifically bundled with a Compaq computer. He then licensed Compaq DOS back to Microsoft.

> From Gates’s perspective, this was an incredible deal. He was able to halt all internal development on Microsoft DOS, saving time and money. From this point onward, every version of Microsoft DOS he sold was, in fact, Compaq DOS, with the digital equivalent of its serial numbers filed off. All Canion asked in return was that Microsoft never release the very latest version of DOS that Compaq provided it until after a few months’ delay. This was to make sure that Compaq always had a slight advantage in compatibility over its rivals.

> Canion even agreed to Gates’s request that they keep the entire arrangement secret, to avoid souring Microsoft’s relationships with the other clone companies. It would remain secret for almost 40 years.

My understanding is that they had pitched the IBM PC compatible machine to TI and had been rebuffed - TI had its own mostly compatible PC offering and the no one in charge was willing to admit it was a mistake.

Trailer is https://www.youtube.com/watch?v=7wjJYqUkHd8

You can watch the documentary on Tubi https://tubitv.com/movies/559438/silicon-cowboys

os2museum.com was just recently able to trace how one particular DOS bug (more than two BIOS harddisk drives would make earlier DOS-versions hang at boot) was handled across different companies, and how and when exactly a fix made it into actual MS-DOS.

Compaq's CEO at the time of the Compaq downsizing and eventual acquisition, Michael Capellas, is now the advisor to the company I work for. And the man who sold the Banyan Vines solution to Compaq in the 90's is now my boss.