I have programmed in Forth It is RPN https://en.wikipedia.org/wiki/Forth_(programming_language) https://en.wikipedia.org/wiki/Forth_(programming_language) Sti

I have programmed in Forth It is RPN https://en.wikipedia.org/wiki/Forth_(programming_language) https://en.wikipedia.org/wiki/Forth_(programming_language) Still used on Some Equipment