The iPhone 5 is powered by Apple’s all new A6 SoC which according to AnandTech, is the first Apple SoC to use its own ARMv7 based processor design whose core(s) are based on something purely created by Apple as opposed to fully licensed ARM cores which the Cupertino company has always used in the past.
Even though Apple has been working on its own ARM based CPU core, it was reportedly having issues making it work. However, it turns out that the reports were not correct after all. In fact, the source has now confirmed that Apple’s A6 SoC is based on Apple’s own ARM based CPU core i.e the ARMv7, and not the Cortex 9 (used in Apple’s A5) or Cortex 15.
Why not just run the Cortex A9 cores from Apple’s A5 at higher frequencies? It’s tempting, after all that’s what many others have done in the space, but sub-optimal from a design perspective. As we learned during the Pentium 4 days, simply relying on frequency scaling to deliver generational performance improvements results in reduced power efficiency over the long run.
At its keynote, Apple promised longer battery life and 2x better CPU performance. It’s clear that the A6 moved to 32nm but it’s impossible to extract 2x better performance from the same CPU architecture while improving battery life over only a single process node shrink.
I should probably give Apple’s CPU team more credit in the future.
The report also says that it cannot be confirmed as to how many cores there are in the A6, as Apple was reluctant to report core count as it has in the past. The number is however assumed to be two, and not four as speculated by numerous rumours in the past.