Macworld UK’s Lou Hattersley takes a look inside Apple’s A7 System On Chip (SoC) , noting that its processor module is much more powerful than other smartphone chipsets. He notes that the A7 was a breakthrough in processing power for mobile devices — the first ever smartphone CPU to offer 64-bit performance, which Apple claims offers desktop-class computing, and concurrently still efficient enough to offer all-day battery life. The operative question, he says, is how did Apple produce a SoC so much more powerful than its rivals.
A System on Chip (SoC) combines multiple component
modules into a single chipset, and at the A7′s “heart” is an ARM processor codenamed “Cyclone” — officially a dual-core ARMv8-A processor running at 1.3-1.4GHz. The other half of the Apple A7 processor is a GPU (graphics processing unit) believed to be a PowerVR G6430. Apple was first to introduce the ARMv8-A to a smartphone, and because it runs at a more efficient clock speed it has better battery life and lower heat, allowing the iPhone to be thinner than other phones, while cached memory is another feature that speeds up operation of Apple devices. The A7 has a 64GK L1 cache for data and 64 KB for instructions, while a L2 cache of 1 MB is shared across the two CPU cores. The A7 also has a 4 MB L3 cache that works across the entire SoC, with the additional memory used to speed up the processor.
There’s lots more that Hattersley reviews in this article, and he notes that AnandTech has determined that the A7 chipset has the same number of execution ports as Intel’s Ivy Bridge (used in Apple’s 2012 iMac, Mac mini and Macbook range) and reorder buffer equal to that of the Haswell architecture (used in the latest generation of Macs), so when Apple refers to the A7 as being ‘desktop class’ – it turns out that wasn’t an exaggeration.
So why has Apple placed such a powerful system inside the current iPhone and iPad range where it’s not nearly being used to anywhere near its full potential at the moment? That remains a mystery for now. Hattersley speculates that Apple may be future-proofing internal components to help maintain a technical edge on its competitors down the line, when the kind of performance offered by the Apple A7 becomes commonplace across mobile devices.
However, current insider scuttlebutt is that an even more powerful A8 SoC is forthcoming later this year. Perhaps a trial balloon for replacing the Intel processors in the current range of OS X computers with ARM chipsets?
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