Up until now, a shroud of mystery has surrounded Apple's custom engineered A4 system-on-chip; we know it's clocked at 1GHz, likely tied to Apple's prior acquisition of P.A. Semi and manufactured by Samsung. Outside of that, the only other knowledge we've gained has come not from the mouth of Cupertino, but from the extracting wizards over at iFixit. The A4 contains at least three layers of circuitry layered on top of each other, though it's packaged just like the iPhone processor: microprocessor in one packa
