The point really isn't to make sure the valves work (the environment might have broken them after a few decades in space), the point is to make sure the code yo

The point really isn't to make sure the valves work (the environment might have broken them after a few decades in space), the point is to make sure the code you're uploading doesn't brick the computer. It's nice to have an original computer and fully replicated signal path to make sure there aren't any unforseen bugs. Emulators have a tendency to have 99% coverage but the missing 1% is what would cause us to throw an expensive brick out of the solar system.