[phaedrus]

Earlier today I was idly wondering: if aliens invented computers and went through the whole 8-bit era, 16-bit era etc. - would they perhaps have developed architectures which had additional "shadow" or "tag" bits on every word? What might they use them for?

The idea being maybe an intelligent race with different balance of motivations might not do only the minimum economical thing, instead being willing to trade X% of memory bits or X% of instructions per second or X% more chips for other purposes. For example extra tag bits might be used to encode where the data came from or its datatype, or additional clock cycles between instructions might be used to run a reliability check on the program as it executes, etc.