If I turn on MMC64 (Options -> Cartridge Settings -> MMC64 set to "on"), the only thing that seems to change is that no disk device works anymore. If I try LOAD "$", 8, I see "SEARCHING FOR N" and then "?FILE NOT FOUND ERROR". Trying to read the error channel returns only nonsense. The same happens with device 9. With device 10, I get "SEARCHING FOR N" and then "DEVICE NOT PRESENT."
I've looked through the manual about 30 times and nothing seems to address this.
What am I missing?