 Forth evolved from Charles H. Moore 's personal programming system , which had been in continuous development since 1968 . Forth was first exposed to other programmers in the early 1970s , starting with Elizabeth Rather at the US National Radio Astronomy Observatory . After their work at <unk> , Charles Moore and Elizabeth Rather formed FORTH , Inc. in 1973 , refining and porting Forth systems to dozens of other platforms in the next decade . 
