THERE ARE FEW BETTER WAYS to detect the decade in which a film or TV show was made than through its characters’ use of technology. Is the hero curiously reliant on pay phones? Does the villain connive via a computer that displays only 72-point green type? The following list of movies and TV episodes offers an incomplete history of how various gadgets have come to dominate our lives, then fade into obsolescence, sometimes for the best: Even if you’re still nostalgic for the iPod, aren’t you glad 13-inch-long cellphones have bit the dust?

‘Desk Set,’ 1957

In the eighth film Katharine Hepburn and Spencer Tracy made together, Ms. Hepburn plays a TV network’s invincibly knowledgeable research librarian. Her job becomes threatened when they install a bus-sized computer named EMERAC (Electromagnetic Memory and Research Arithmetical Calculator), capable of almost instantly solving problems that would have taken her the better part of an hour. Later, EMERAC goofs up royally, printing pink slips laying off everyone in the company. For some reason, this bleak view of early computing was sponsored in part by IBM. 

‘Mad Men,’ Season 1, 2007

Throughout the first season, initially set in 1960, we regularly see female staffers at the Sterling Cooper advertising agency operate its switchboards, manually connecting cords into the appropriate sockets so that the (mostly male) execs could communicate via telephone. Though these women work behind the scenes in a tiny room deprived of Rothko paintings and potted plants, their control of the phone lines gives them influence. 

‘WarGames,’ 1983

A teenage boy (the young Matthew Broderick)—who’s equipped with a beeping, blipping, buzzing phone modem—inadvertently hacks into a military supercomputer. Believing it to be part of a videogame he’s stumbled upon, he activates a simulation that convinces U.S. officials they are under attack. At one point in the film, he places a soda can tab in the mouthpiece of a pay phone, allowing him to make a call without paying for it.