The Forth computer language was invented by Charles Moore: http://colorforth.com/
Forth is extensible, can be its own os, and in general makes tiny powerful programs.
Forth has been a recognized programming language since the 1970's. ColorForth is a redesign of this classic language for the 21st century. It also draws upon a 20-year evolution of minimal instruction-set microprocessors. Now implemented on modern PCs, it runs stand-alone without an operating system. Applications are recompiled from source with a simple optimizing compiler.
gforth is a forth that runs on an os, and is ANSI forth:
pacman -S gforth
starting forth is a good book to learn forth by leo brodie: http://home.iae.nl/users/mhx/sf.html