From Iris to Nitro to Nintendo DS, the dual-screened "developer system" went through hell and high drop tests before becoming what it's known as today — the predecessor to the 3DS.
Did You Know Gaming's video is full of nifty tidbits about Nintendo's first foray into dual-screen gaming, the butt of jokes from its unveiling to its release, when everyone quickly shut up and started playing. So compelling was this new form of gaming that the DS went on to become one of the most pirated game systems of all time. Being incredibly easy to hack probably helped.
Yet, for all the time I spent with my original DS, all of my memories of that handheld have been supplanted by the 3DS. Thanks to backwards compatibility (and the DSi failing to deliver any substantial exclusive games), I can barely recall when one ended and the next began.