It’s now the Marketplace at East Falls, but 3747 Ridge Ave. is the birthplace of something bigger.

Outside, there’s an inconspicuous, blue historical marker. Think of the cell phone pulsating next to you, the car that whizzed by a second ago, and the platform you are on at this very moment. Philadelphia played a massive role in developing the background of this technology.

The inky blue sign only winks. It was placed there in 2006 to commemorate the site of the first commercial digital computer, the Binary Automatic …