It was a defining moment in American history, albeit one run over and over, like an episode of "Star Trek." Into the tidy living room of a young family's subur- ban home, usually just days before Christmas, came the electronic marvel. The old ma- hogany radio set, already seeming a bit an- tique, was shoved into a corner, and two hefty deliverymen struggled to position the bulky new console across from the couch, between the easy chairs. Everyone gathered around as the first test pattern...