Hi, I am working on implementing local variable support in OpenBIOS. I have done a lot of research on the issue, but there are a few issues I still need help resolving. 

-Does Openbios context switch when a word is called? This is when all the registers are saved into a stack frame, so the currently executing word can use them.

-Could someone give me a tutorial on how to add c functions to forth and make them accessible to the interpreter. I want to be able to add words to the dictionary and be able to use them from the command line.

- Would anyone know which register on the PowerPC would be good for using as a stack pointer for a new local variable stack? I think r13 is free and a possible candidate. 

If anyone could give me a few pointers, it would really speed up my ability to improve OpenBIOS.