In this episode we look back at (aspects of) the North American Air Defense system in the cold war. In particular, we look at the distant early warning line(s), the F-106 interceptor and the SAGE computer system. For DEW, we talk with Mike Milinkovich and Brian Jeffrey who have both worked on the DEW line; Brian also maintains a great website on DEW. For the F-106, we talk with Richard Embry who has flown the interceptor. And for SAGE, we speak with Bernd Ulmann, who has written a very detailed book on SAGE's underlying AN/FSQ-7 computer system. Bernd has also been a previous guest on Episode 159 on analog computers.