Unless a positronic brain is created that has all the causal powers of neurons, and matches a human brain in functionality one-to-one. So the "software" isn't explicitly coded - it is built up through sensory experience. Could you even (ethically) sell such a robot? A synthetic being that is conscious of itself, free, and perhaps, moral.
That was my impression: the 140 character limit is defining of Twitter. It was good to have messages condensed to a certain specification when attention of users became so in demand. That led to the use of link shorteners in tweets, though. This change partly addresses that.