Nintendo rewrote firmware between 2.1 and 3.0. However, theoretically it wouldn't matter what version it's on if you boot without patches because it'll act more as a bootstrapper. Every other CFW applies patches which would probably break it, but Cakes won't apply any patches unless you tell it to.If you can get it to accept a 1.0 firmware.bin and boot it correctly. I'm not sure if it would since it's not made with that old firmware in mind and the very early firmware versions are very different from newer ones.