Answer: OS / 2
In April 1987, IBM and Microsoft held a joint press conference to announce an ambitious new project, a next-generation operating system called OS / 2. The promise was that MS-DOS would be faster and better should be replaced to improve the overall computer experience.
The two companies had collaborated on the project over the last two years, although at the time of the announcement the case was still under development ̵
Although OS / 2 had some clear advantages over MS-DOS and Windows, this was quite the case. Excellent for multitasking – ultimately expressing hardware dependencies, poor acceptance rates, and an increasingly Windows-oriented PC market.
While IBM tried to reinvent OS / 2 several times over the next decade, it was ultimately the case faded in the dark. The last major release was in 2001 and support was discontinued in 2006. OS / 2 is pending in some small niche markets, such as banking networks and metro control systems, but is otherwise widely used as a footnote in the history of computing.
Courtesy of IBM.