I own the MC6400 for a while by now, but never did anything serious with it. Yesterday I typed in the NIM Game from the manual; given that that takes 20+ minutes I never dared to do that before given the lack of reliable storage. This has changed with PicoRAM now. The program is also on the program audio cassette that came with the machine, but I wasn’t able to load any of the programs from the 40+ year cassette. Really enjoying it now.