(Moved to COFF) I rather like FORTH. Its chief virtues are that it is both tiny and extensible. It was developed as a telescope control language, as I recall, and in highly constrained environments gives you a great deal of expressivity for a teeny tiny bit of interpreter code. I adored my HP 28S and still do: that was Peak Calculator, and its UI is basically a FORTH interpreter (which also, of course, functions just fine as an RPN calculator if you don't want to bother with flow control constructs). But I also make the slightly more controversial claim that FORTH is just LISP stood up on end. These days I think the right choice for those sorts of applications would be Micropython. Yes, a full-on Python interpreter is heavyweight, but Micropython gives you a lot of functionality in (comparatively) little space. It runs fine on a $4 Pi Pico, for instance, which has IIRC 256KB RAM. And if you find yourself missing TCL, there's always Powershell, which is like what would happen if bash and TCL had a really ugly baby that just wouldn't shut up. The amazing thing is that access to all the system DLLs makes it *almost* worth putting up with Powershell. Adam