So I just gave this a try tonight. Assembled a very small test program under OS9, transferred it to a DECB partition, rebooted to DECB and ran the program. Tools used: MINTED editor, CSC6809 assembler, S1LOAD to convert hex file to binary, RSDOS to manipulate files in a DECB partition from within OS9. http://www.youtube.com/watch?v=_H1Q9xsc0p8 Dave