complete FORTH system should be in the range of 32-40
That can be difficult to achieve, currently the full build is 150k
C code +
100k Forth. I don't know how much of the Forth is needed. Taking out
unwanted drivers etc. could help a lot on C side, but down to 30-40k?
Most Forth systems can be stripped to (much) less than 8kB, so
32kB is definitely achievable; it all depends on how much, and
what, functionality you want.
Rolf, since you said you can already run "bare" C code and you
don't need a "BIOS", you're probably better off using a normal
Forth system on your machine, and save yourself the work of
stripping OpenBIOS until it is what you want.