How do you sell a PC for $35? In the case of the Raspberry Pi, the British foundation which created it reduced computing to its most stripped-down essence. The Model B is a tiny bare circuit board: You supply a power source, a memory card and an operating system, not to mention a display, a keyboard and a mouse. The notion here isn’t to compete with anything you’d pick up at Best Buy; instead, the Pi is meant to help young people learn about technology, including students in countries where even $35 is an imposing chunk of change. But even if you’re not part of the target market, this exercise in inventive minimalism is inspiring.