Watcom C
The Watcom C language and compiler was really popular in the early 1990's because of it's optimizations for the Pentium CPU, along with its ability to target MS-DOS, Windows 3.1, OS/2 in both 16bit and 32bit flavors. Watcom C also added the ability to target Novell Netware. Watcom C includes both register & stack calling compilers, which depending on the targeted CPU can yield better results.
10.0
This version bundled the popular DOS/4GW dos extender, and was made popular by such games as Doom. Version 10.0 included the Win32 SDK for Win32s & Windows NT 3.1, the Windows 3.1 SDK, and the OS/2 1.3 & 2.0 SDK's for OS/2 development. Additionally it included the MFC libraries.
11.0
This updated the Windows NT support up to 3.5 levels.
OpenWatcom
Watcom sold all the compiler technology to Sybase where it languashed, then it was swept up by Powersoft. It was then opensourced, and is free to all including it's FORTRAN.
The current version is 1.8
