Conversation

@jk Gotta go old school for that sort of longevity

1000 years sounds possible

Depending on your definition of computer it's already been done with the Antikythera mechanism

https://en.wikipedia.org/wiki/Antikythera_mechanism

Put that in a vault and not at the bottom of the sea and I bet it'd still work

More useful would probably be a Babbage Analytical Engine built with modern materials