The ARM2 had about 30000 transistors and was already capable of doing significant things. The questions then are: * How would you build a transistor? * How w

The ARM2 had about 30000 transistors and was already capable of doing significant things. The questions then are: * How would you build a transistor? * How would you build thousands of transistors? * How would you make them reliable? * How would you power them? * How would you implement memory? Depending on what materials you have to hand, and your abilities to machine them, and your power sources, many alternatives present themselves. You could even consider analog computers.