Mill Computing, Inc. Forums The Mill Tools Simulators Simulation Reply To: Simulation

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Good to hear of another person interested in Forth on the Mill.

I started three wiki pages about “Mill Forth.” See:,_better_suited_to_the_Mill

Please take a look and feel free to add your ideas, perspectives and useful links. Same for anybody else reading. If you’re logged into the forums, you should also be logged into the wiki.

The idea of using the belt and scratchpad to serve as Forth’s data stack is attractive for speed reasons. However, I think that’s not the right approach for an initial version, since the belt doesn’t model a FIFO stack. While I’d like to let the Mill’s call/return machinery be Forth’s return stack, I don’t think that’ll work well, because the inner interpreter needs read/write access the stack for more than just call/return matters, including for the common DO … LOOP constructs. Breaking the interpreter’s ability to manipulate the return stack would IMHO make the result too far from Forth.

Overall, I agree that the only people likely to be porting much existing Forth code to the Mill are those of us interested in Mill Forth. Still, my instinct is to design something that’s recognizably Forth, for the first iteration. A belt-oriented interpreted language (or a type-aware Forth) are interesting notions, but I’d like to separate those from getting a Forth interpreter running on the Mill (initially under sim.)

So, my instinct is to go for a fairly vanilla port of Forth for the first iteration, with both stacks in memory. Doing so does not preclude using the Mill’s stack pointer, though the automatic stack cut-back upon true function return might make that problematic. Though if the inner interpreter never returns, we might be able to use it that way.

Happy New Year,


  • This reply was modified 7 years, 4 months ago by  LarryP. Reason: clarity