Is the A6 in the iPhone 5 using a big.SMALL triple-core configuration?

There have already been a number of articles on the A6 but Anandtech’s and the one published by the Linley Group are the two that stand out from the crowd. The one published by Anandtech in particular mentions that Apple will come up with its own custom ARM-based cores, rather than use either a dual core Cortex-A15 or a quad Cortex-A9.

Anand says that there are hints in the new version of Apple’s development tool, Xcode v4.5, which brings in a new architecture armv7s, the major difference being support for VFPv4 extensions which the Cortex A5, A7 and A15 support, but the older A8 and A9 don't.

The writer went on to highlight the fact that the A5 and the A7 were nowhere near fast enough to rival the Cortex-A9 used in the Apple A5 of the iPhone 4S, which meant one of two things. Either the A6 contained the Cortex-A15, or the A6 contained a custom-made ARMv7 processor core.

There are only a few companies that have an ARM architectural license. This license allows companies to be more innovative with their products whilst still maintaining compatibility with the wider ARM ecosystem. Such licensees include Marvell, Qualcomm, Intel (via the StrongARM acquisition), Apple (never confirmed), Nvidia, Microsoft and AppliedMicro.

Now then, could it be that Apple has implemented the triple-core SoC on the market using ARM’s big.LITTLE design by matching two high performance cores with a secondary processor like the Cortex-A7/A5? Nvidia already does something similar with the Tegra 3’s 4-plus-1 and so did TI with the OMAP 4 (which includes two M3 cores).

Could those two cores be refined into fine-tuned versions of the Cortex-A9 with VFPv4 extensions, rather than light versions of the Cortex-A15?

The main advantage of doing this is that you dramatically improve battery life and still manage to provide significant CPU resources when required. A demo by ARM last year showed that switching between processors only took around 20ms and was transparent to the OS.

It’s worth noting that the battery capacity of the iPhone 5 is almost the same as that of the iPhone 4S. This means that something has to give, bearing in mind that the iPhone 5 has a much improved battery life (12.5 per cent longer on Standby, 11 per cent on Wi-Fi and a whopping 33 per cent more browsing time on 3G). That’s despite an LTE modem and a bigger display with a higher resolution (18 per cent more pixels).

What’s more, Geekbench benchmark results show that the dual-core processor is clocked at 1GHz (a third processor won’t appear), only marginally higher than the 800MHz the A5 hits.

Check out our article on how the A6 could be a real danger to the world of x86.