>>18This one's right. It's possible to envision a computer with infinite memory where no address would ever get overwritten. The computer would always just write to free memory, eternally increasing its accessible store of data. You would need infinite-length addresses though, but that's probably achievable if the memory is infinite in the first place.
>>20And you would also need an output device with infinite memory. This would also allow to backtrack to any past output from the beginning of time.