My memory isn’t what it used to be but many years ago I was taking a college course on computing and the professor brought in a copy of IBM Windows. He said that Gates at first tried to release it through IBM but it didn’t work out so Microsoft was born. His mother was friends with the CEO of IBM so it was a foot in the door, but when I did a search for IBM Windows I couldn’t find any results. Perhaps I dreamed it.
Microsoft was born to produce BASIC for the ALTAIR computer in 1975-76. The company bought XENIX (UNIX) and sold that as an operating system. Then IBM approached Microsoft to produce a CP/M-like operating system for the new IBM-PC (1981). Microsoft bought QDOS from Seattle Computers, rebranded it as MS-DOS, and licensed it to IBM as PC-DOS. It wasn’t until after the Apple Macintosh came out in 1984 that Microsoft recognized the value of a graphical environment, so they produced Windows in 1985. They eventually sold XENIX to concentrate on Windows, and worked with IBM to produce OS/2, ....
... and the story goes on from there...