The 8501 has 256 bytes of ram and runs forth. There are other PICs with less memory, but they usually run a "hosted" forth (e.g. a 3-inst-forth variant), so I wasn't going to count them.
Since Forth's source and code forms are equivalent (like assembly), I don't think it matters whether it's compiled or not. Pretend it's source-code form is the "annotated" and "commented" form.