You may be familiar with the GNU C Compiler from the GNU Project, found on pretty much any Linux distribution. Previously, if you wanted to compile programs using GCC on DOS, you used DJGPP (DJ's GNU Programming Platform) from DJ Delorie. But programs compiled using DJGPP require a 32-bit CPU.
TK Chia has been working to port the GNU C Compiler to DOS, using the ia16 instruction set. While compiling with gcc-ia16 requires a 32-bit CPU, the generated programs will run on any 16-bit CPU. TK Chia recently posted the latest packages for gcc-ia16 at Github. Go grab them!