OS/2 was developed as a joint venture, under the codename "CP/DOS" initially, between Microsoft and IBM in the late 1980s through to 1990 when the agreement fell apart. Microsoft's original intention was to replace Windows with OS/2, but when that didn't work out, they took what they had developed and produced Windows NT while developing the existing Windows product into Windows 3.x. Meanwhile, IBM took what they did and produced OS/2 2.x and later, long before Windows NT.

After quite a bit of experimentation with various emulators and configurations, I finally got OS/2 1.3 to run! Both IBM and Microsoft had their own versions, this is the Microsoft "Server" release.

No real fancy splash screen here. Just Microsoft throwing a bunch of their software patents into your face.

This is the OS/2 1.3 desktop. As you can see, it bears a very big resemblance to Windows 3.x, as opposed to Windows of the time. Obviously, the preferential treatment of OS/2 over Windows was running rampant at this time.

The "Desktop Manager" is set up in a very similar way to Windows 3.x' "Program Manager", except that it uses separate windows as opposed to a single MDI window. A shortcut to a DOS prompt and the Print Manager are open all the time and cannot be closed. The Desktop Manager also uses large-sized icons, like the Macintosh and the later Program Manager.

The File Manager is practically identical to the one in Windows 3.x.

It is possible for files to have all kinds of "extended" attributes not present in DOS/Windows files, as part of OS/2's HPFS file system. This is also available as an add-on to FAT, as shown here.

This is the OS/2 command interpreter, which is roughly DOS equivalent.