Lets say your region becomes isolated for some reason: How'd you build computers in that situation?
If I understand correctly there's plenty of factories around the world capable of manufacturing 1980s-era microchips. And if your region doesn't have one, projectors can with some effort be repurposed to write microscopic circuits onto photosensitive silicon.
You'd still need to find somewhere to get the materials... And purify them... I don't feel qualified to comment on that!
1/3?