Windows 3.0 / 3.1 for Workgroups 3.1
Windows 3.x was the first to gain significant development and commercial traction. It combined the 8086, 286, and 386 modes of Windows 2 in to one package. It replaced the MSDOS Executive with a Program Manager and File Manager similar to those in OS/2 1.x. Much of its success was spurred by the availability and success of Microsoft Office. Although Microsoft would have had you believe otherwise, Windows 3.x was the direct foundation for Chicago/Windows 95.