How big, exactly? Well, 13-inches in the case of the prototype iPad, and "larger than 4 inches" in the case of the prototype iPhone handsets.
For comparison's sake, the display on the current model iPad measures 9.7 inches from top right corner to bottom left. (The iPad Mini screen is smaller, at 7.9 inches.) Meanwhile, the iPhone 5, which was released last fall, is equipped with a 4-inch display – up from the 3.5 inch screen on the previous model iPhone.
The usual rumor mill caveats apply here: Apple isn't commenting on the Journal report, and the newspaper is sourcing the whole thing only to anonymous "officials at the company's suppliers." Still, it makes sense. Here's why: Despite Steve Job's contention that the 3.5-inch display was the "perfect" size, smart phone screens are getting larger, from Apple's own devices to the popular Samsung Galaxy S3 and S4 lines (to say nothing of "phablets").
It makes sense that Apple would want to test out a plus-sized smart phone, even if the prototype never makes it to production.
As for the larger iPad, we doubt that Apple will get rid of the 9.7-inch model. But just like the Cupertino company offered a smaller version of its tablet in the form of the iPad Mini (tagline: "every inch an iPad"), it's possible that it could eventually offer a larger version, too.
Of course, it's worth noting that a 13-inch display would make for a pretty large tablet – one that would be harder to fit into handbags and backpacks. Consider the fact that when Toshiba unveiled a 13-inch tablet last year, Mashable called the device "monstrous."
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