CPUs certainly will be produced on Earth for a while due to the very low mass (which makes transport costs negligible even over interplanetary distances). But M

CPUs certainly will be produced on Earth for a while due to the very low mass (which makes transport costs negligible even over interplanetary distances). But Mars certainly will want to produce the vast majority of their own stuff due to very high transport costs. And as far as Mars being cut off, certainly Mars will want to trade with Earth for as long as possible. Self-sustaining will hopefully remain theoretical. That doesn't mean they won't have the capability to do so if necessary.