The sources also claim that Fab 14 is designed to crank out chips based on a 20 nanometer process. Most of Apple's current mobile products run 32 nanometer chips; the first was the March 2012 A5, which powers the iPad mini, iPad 2, and fifth-generation iPod touch. The A6 in iPhone 5 and A6X in fourth-generation iPad also use this process.
Shifting to 20 nanometer can reduce a chip's overall size, improve compute power, and reduce battery demand. But in keeping with past practice, Apple may first quietly introduce a new process architecture in a under-the-covers update of a low volume product, such as Apple TV, before introducing it into the iPhone. Wikipedia has a handy list of Apple's A series processors to date.
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