Do you mean the 1940's or the 2040's?
If you are talking about the 1940's, I would say look no further than the first Back to the Future movie... the first video game eas invented in the late '50's and people were amazed by it... I think they would be dumbfounded by today's technology... By the 2040's what we have now (if the system lasts that much longer) would be antiquated
one of my favorite quotes: "Any sufficiently advanced technology is indistinguishable from magic." - Arthur C. Clarke