The Apple A7 system-on-a-chip (SoC) is at the heart of every iPhone 5s, iPad Air, and Retina iPad mini. Systems-on-a-chip integrate many if not most of a device's processors into one integrated circuit. In the Apple A7's case that includes the the industry-leading, 64-bit ARMv8-based "Cyclone" central processing unit (CPU) and a PowerVR G6430 graphics processing unit (GPU).
The Apple A7 replaced the Apple A6 and Apple A6X found in the iPhone 5 and iPad 4. Apple says the A7 is twice as fast at both general purpose and graphics processing as its predecessor yet it remains roughly the same size. More interestingly, the A7 is 64-bit - the first 64-bit processor crafted for a consumer smartphone - and it supports OpenGL ES 3.0.
Apple A7: History
Apple began designing their own chipsets in 2010, licensing the ARM Cortex A8 for the Apple A4. In 2013, Apple switched from licensing a chip to licensing an instructions set architecture (ISA), ARMv7, so they could create their own custom chip, the Apple A6. The CPU was codenamed Swift. It was a 32nm CMOS dual-core Apple processor clocked up to 1.3GHz and they paired it with a triple-core PowerVR SGX543MP3 GPU and 1GB of DDR2 RAM.
Apple A7: Cyclone 64-bit CPU
Now, with the Apple A7, Apple has created their second generation custom CPU, this time codenamed Cyclone. Anandtech sleuthed out the name and deduced many of its likely details. Cyclone is 28nm now, still dual-core and 1.3GHz, but based on the new 64-bit ARMv8 ISA.
Like capacitive touch screens in a world that's resistive, and Retina displays when all eyes are on standard, 64-bit looks great on a slide, on a website, on a smart sign, and on a box. It sounds advanced. It sounds better than. It sounds leading if not bleeding edge. In a time when superficial public opinion is leaning away from Apple-as-innovator, innovative-sounding messaging could not be any more important.
It can also be confusing, however. Mass media has mostly been told - and passed along - the most obvious consumer-facing benefits of the bit-space, like the ability to address more than 4GB of RAM, and to work on much larger image and video files. It's easy to imagine a future where more powerful iPads and Apple TVs - both of which share the same processor architecture and operating system as the iPhone - can benefit from those capabilities, not to mention the Mac on ARM project at Apple that we might see the fruits of one day. It's harder to see an iPhone with 6 or 8GB of RAM any time soon.
Luckily the Apple A7 comes with several other advantages as well. First, the 64-bit ARMv8 instruction set is just flat out more efficient than the old 32-bit ARMv7 one was, and that efficiency helps. Second, the A7 is providing twice the general-purpose and twice the floating point registers as the A6 processor. Which was plenty fast already. The ability to chew through registers in particular is also a net positive. Registers are the memory units inside CPUs. They're what hold the bits being operated on at the moment. The more bits that can be held at once, the more operations that can be performed at once. And just like keeping bits in RAM is faster than moving them back and forth from physical storage, keeping them in registers is faster than going out to RAM or storage to get them.
Apple has already transitioned iOS 7. That includes native, 64-bit kernel, libraries, and drivers, built-in apps. They also made it as easy as possible for developers to compile for both 32- and 64-bit in Xcode, and will load both 32- and 64-bit frameworks on-device so the transition will be transparent and painless for customers as well.
Apple A7: Power VR Series 6 with OpenGL 3.0 ES
The Apple A7 Cyclone CPU is paired with an OpenGL 3.0 ES capable PowerVR Series 6 (Rogue) graphics processor, potentially the G6430, and 1GB of DDR 3 RAM. Apple claims the A7 GPU is also twice as fast as the A6. It's arguable whether or not Apple "gets games", and what they do with next-generation iPads, Apple TVs, and future devices remains to be seen. However, while "Console quality" is a term that gets thrown around a lot, 64-bit and OpenGL ES 3.0, shows Apple putting their tech where their mouth is.
Apple A7: The bottom line
It's hard to really appreciate speed until you go back to something that isn't as fast. Be it broadband vs. dialup, LTE vs. 3G, SSD vs. HDD, or a processor that's twice as fast vs. one that now feels twice as slow. But the difference, one you might never have noticed before, becomes instantly apparent. iOS 7 will be pushing the limits of modern smartphone hardware. Increasing those limits will not only make iOS 7 perceptibly better, but it will make the kind of apps iOS 7 can run perceptibly better as well.
So does that make the iPhone 5s over powered, or the iPad Air underpowered? Neither — they're both over powered.
If Apple sticks to pattern, the Apple A7 will be replaced by the Apple A8 by the end of 2014.