Despite the refrain at the time that it wasn't an OS, in hindsight I feel that's a pretty tenuous claim. It just used DOS as a hardware abstraction layer. The

Despite the refrain at the time that it wasn't an OS, in hindsight I feel that's a pretty tenuous claim. It just used DOS as a hardware abstraction layer. The Win16 API provides processes, memory management, IO abstractions, and many other OS-like features. Eventually in the late 3.1 era they'd even move the disk drivers and file system into the Windows kernel. (The so-called 32-bit disk access.) Similar for DV/X in many ways.