Analyst says Apple A6 processor uses custom CPU core

Analyst says Apple A6 processor uses custom CPU core

LONDON – Linley Gwennap, founder and principal analyst with The Gwennap Group (Mountain View, Calif.), says that the A6 processor at the heart of the Apple iPhone 5 smartphone uses an internally-developed ARM-compatible processor core rather than Cortex-A15 processor core licensed from ARM Holdings plc. This contradicts financial analysts at Nomura Equities Research who declared in a note to clients that the A6 is a dual-core Cortex-A15 processor manufactured for Apple by Samsung in its 32-nm HKMG process technology.

In an online article Gwennap agrees that Samsung is the probable manufacturer but points out that iPhone 5 applications have to be recompiled to a new instruction set architecture variant called ARMv7s. This he reckons adds weight to the idea that it includes custom processing cores and certainly shows that the A6 does not use the same Cortex-A9 cores that are in the Apple A5 processor. The ARMv7s instruction set architecture is reportedly compatible with the Cortex-A5, Cortex-A7 and Cortex-A15 but nonetheless Gwennap supports the idea of a custom processor.

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"We believe the custom A6 CPU is similar in complexity and performance to Cortex-A15 as well as to the Krait CPU that appears in Qualcomm's newest processors. To reach Apple’s claim of a 2x performance gain over the iPhone 4S (which uses the Apple A5 processor), we expect the A6 contains two CPU cores clocking at roughly 1.2GHz," states Gwennap in the article. Qualcomm is an architectural licensee of ARM Holdings plc (Cambridge, England) so while Krait is similar in performance to the Cortex-A15 it is substantially self-designed while remaining compatible to the ARMv7 instruction set.

Gwennap takes the view that the A6 processor is the first result of an ARM architectural license taken to complement the acquisition of P.A.Semi by Apple for $278 million in cash back in April 2008. Soon after the acquisition ARM announced the signing of an architectural licensing deal with an unnamed "strategic OEM." There was speculation at the time that this might be Apple.

It is Gwennap's contention that back in 2008 Apple set its newly-acquired IC design team off on two projects; a near-term team to quickly develop processors around licensable ARM cores to create the A4 processor and a longer-term team to use the architectural license, which has resulted in the A6 processor.


Related links and articles:

Linley Gwennap article

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