For the development phase I would like to have a real Forth system, interpreting ascii source. For flight the number & size of telecommands is limited, therefore it would be nice to have bytecodes with a bytecode compiler/decompiler to be used on ground. That's why I'm thinking about FCode.
FCode isn't full-featured Forth though, it's more like a scripting-language subset. In particular, it doesn't have DOES> . FCode isn't much smaller than (compressed) source text either, btw.
Segher