This is much like C. The easiest way to use assembly in C or Forth is to know your 'ABI' and write separate assembly code functions where needed. In Forth at least you can write a CODE word.

Yes, though:

- high-level Forth also amounts to a Turing-complete macro assembler (much better than textual macros)

- C was less practical/available on early personal computers, especially for coding right on the target system. When I was doing this it was on a TI 99/4A in the early 80s.