BUCHAREST, Romania—Mihai Moldovanu grabs the cardboard box with the enthusiasm of a man from the future who’s opening a time capsule.

“Maybe it could still work,” he tells me.

He dusts it off with his hands. Inside the box rests the computer he built for himself in high school. He hasn’t switched it on in 10, maybe 20 years. This summer, when moving from one apartment to another, he stumbled upon the box. “I need to find a charger and an old TV set. It’s going to be tricky to revive it.”