Insiders call it Vallco Parkway. The nondescript building, just a quick hop down 280 from Apple’s Infinite Loop headquarters in Cupertino, houses a nerve center crucial to the fingers of everyone who uses a Macintosh. This is the Input Design Lab, where Apple designs and tests the prototypes for new keyboards, trackpads, and mouses. It’s stuffed with a treasure trove of precision machinery that would make geek hearts patter like a pneumatic drill. Until now, no reporter or press photographer has crossed the threshold. But to mark a new set of iMacs — and perhaps to help implement a spirit of more transparency in the previously locked-down corporation — Apple opened its doors (well, some of them) to Backchannel, and talked about its new iMacs and overall strategy. (See related story: “Why Apple Is Still Sweating the Details on iMac”.) Here’s what we saw.

In a user test lab, Apple puts subjects before keyboards and wires them up to sensors to measure how typing on the unit affects the body. “We do internal user studies, using a wide cross section of people,” says Kate Bergeron, VP for Ecosystem Products and Technologies. (She’s basically Apple’s czar of input devices.) “We monitor muscle fatigue and memory, acoustics, accuracy, and other tests on all the keyboards.”