Microsoft had a Unix distro for a long time - Xenix. It was built as Microsoft's next generation OS, originally Microsoft thought they were going to migrate to

Microsoft had a Unix distro for a long time - Xenix. It was built as Microsoft's next generation OS, originally Microsoft thought they were going to migrate to it as their dominant platform as computers got faster. It was the most widespread version of Unix around in the late 1980s in terms of machine installs. Microsoft sold it to SCO in 1987.