The last is particularly applicable to those who don't own PCs, since most cross-assemblers require PCs or workstations these days. I'm painfully aware of the tradeoffs. So I'm going to take a radical position for a Forth programmer, and tell you to choose for yourself . You have to recompile the C source to add new primitives. Some C Forths use inefficient threading techniques, e.g. a CASE statement.
Most C compilers produce less efficient code than a good assembly-language programmer.
But for Unix systems and RISC workstations, which frown upon assembler, this may be the only way to get a Forth up and running. On a Z80 or 8051, quite the opposite. But even if you plan to write a Forth in C, you need to understand how Forth works in assembler. This is a shareware product available from the GEnie Forth Roundtable. Note that the published code is for a fig-Forth variant and not F83.