Reply To: Simulation

Tomberek, Ivan and others interested in Forth or similar:

Ah, Forth; the name brings back good memories!

One could certainly port Forth to the Mill — or one could design/implement another interpreted language that makes better use of the Mill’s architecture (and thus almost certainly faster, simpler and thus likely usable sooner.) Which way to go depends mainly on whether there’s real demand to run existing Forth code. People have done some amazing things in Forth (e.g. Chuck Moore, Forth’s creator, who wrote his own chip-design system in Forth, if I recall correctly), but I’m not sure how many prospective Mill users/programmers/system-designers want to run existing Forth code.

On the other hand, having a working interpreted language for the Mill (either via a simulated Mill or a TBD implementation on an FPGA) would IMHO provide a more programmer-friendly way to try out the Mill than the current assembly/simulation tools — and sooner — even if it’s different than Forth. To me, that seems like a worthwhile option to explore, especially since the LLVM toolchain sounds like it won’t be ready as soon as we might wish.

A small, efficient, interpreted language — one designed to make use of the belt model — might well be easier to implement, especially since (as I understand it) the core interpreter will have to be written in Mill ConAsm (at least until the Mill’s specializer is ready to generate simulate-able/runnable Mill executables GenAsm

Ivan, any projection on when you’ll be able to simulate code written in GenAsm internally? (Or is that working already?)

I find myself leaning somewhat toward a not-textbook-Forth interpreted language for the Mill, because many of the most common Forth “words” (such as dup, swap and over) are for juggling values on the stack, so the word you really want to invoke has all its operands on the stack in the correct order. It seems a shame to enforce strict stack semantics on a machine that has something arguable better (the belt) built right into it. However, it there is real demand (or even strong interest) for Forth itself on the Mill, I’d still be interested in getting that working.

Tomberek,
especially if you’re learning Forth and haven’t done a port, I suggest

Threaded Interpretive Languages: Their Design and Implementation

by R. G. Loeliger. Probably out of print, but used copies are apparently available from a certain large online book (and everything else) seller.

I’d be interested in further discussion and possible collaboration. Feel free to email me at: ursine at (a large, free email service, hosted by g00gle.)