The brain is a mess. It's a computer whose bits have been repurposed, patched, extensions tacked on all around the place by a million different engineers none of whom comment the code or document the hardware changes. The cabling is all over the place and unlabelled. It's good at at certain things and appalling at lots of others. It can't even remember a short list without re-inputing it a couple of times, the arithmetic module is rubbish and as for the logic module ...