the ROM checksum always is bad. 910111 is the one to go with, however other versions should boot aswell. For the charset, get a c64 one from zimmers.net and rename it. Try without a bootdisk at first, you can still mount it later. Please also make sure all switches on the board are set to OFF position. As you noticed, our SD implementation is not super clean yet so if you fiddle around, reformat (fat32) the card from time to time. Put the bitstream on it first, then the ROM, then the charset if you have one, then the bootlogo if you have one. Hope that helps - good luck and let me know!