When you ask most iPhone 4 owners why they didn’t get Siri in a software update for their devices when the almost-identical iPhone 4S came out, the common answer is extremely cynical: Siri is the arbitrary, software-only feature that Apple decided to limit to the iPhone 4S simply to differentiate it from the iPhone 4 in marketing,
The truth? Apple may not be as cynical as all that. In fact, according to a new report from a chips analyst, it all comes down to special noise-reduction circuitry unique to the iPhone 4S’s A5 chip.