Win32s
Win32s is a 32-bit application runtime environment for the Microsoft Windows 3.1 and 3.11 operating systems. It allowed some 32-bit applications to run on the 16-bit operating system using call thunks. A beta version of Win32s was available in October 1992. Version 1.10 was released in July 1993 simultaneously with Windows NT 3.1. The final Win32s version 1.30c was released in February 1996.