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Much of the speed gain stems from the A5 chip which first appeared in iPad 2 this Spring. Apple says the dual-core A5 chip inside iPhone 4S enables two times faster CPU performance and up to seven times faster graphics versus nine times graphics performance on iPad 2. The discrepancy in graphics performance between iPad 2’s and iPhone 4S’s A5 chip likely is attributed to a lower clock frequency on the latter, a concession to preserve battery life. Apple says Siri, an AI-driven personal assistant feature exclusive to iPhone 4S, cannot be realized on earlier iPhone versions due to significant computational requirements (although that doesn’t stop hackers from trying). The A5 chip is thought to pack in a dual-core Cortex-A9 processing core from ARM Holdings, Imagination Technologies’ PowerVR SGX543 MP2 graphics unit (also dual-core) and 1GB of RAM. None of this has been officially confirmed because Apple doesn’t go into chip details and its partners are mum on the matter as well, so we’ll have to wait for an x-ray analysis for some clue. In addition to Siri, the chip’s digital signal processing capabilities are also being utilized to stabilize shaky video in real-time when recording clips using the built-in Camera app (and likely in other places as well).
