Why Apple Went with a 64-bit A7 processor in the iPhone 5s


A7 64-bit

When Phil Schiller presented the iPhone 5s just a couple days ago, he highlighted one of the key features of the handset, and that is the custom-made, 64-bit desktop-class A7 chip. Of course, there is a lot of hyperbole in Apple’s claims about the wonders of 64-bit computing, so we need to look beyond that to fully understand the company’s move to make the first smartphone with a 64-bit processor.

Here is what the company’s head of worldwide marketing said (I used his title on purpose):

This is the first-ever 64-bit processor in a phone of any kind. I don’t think the other guys are even talking about it yet. Why go through all this? The benefits are huge. The A7 is up to twice as fast as the previous-generation system at CPU tasks, and up to twice as fast at graphics tasks, too.

So why does Apple’s 64-bit A7 chip makes sense? The question is timely, because some experts say that in order to benefit from 64-bit, you need to have more than 4 GB of RAM in smartphones. Well, this era is yet to arrive.

So, why 64-bit? First, because of its speed: the early benchmarks seem to reinforce Schiller’s claims of up to double the speed of the previous-generation iPhone. Speaking with AllThingD, Carl Howe, VP of research and data sciences at the Yankee Group, said that 64-bit also means that for some code the A7 will be twice as fast or faster to run code, because the processor doesn’t have to use main memory as much.

Another benefit comes from the ARMv8 architecture on which the A7 is based. Kevin Krewell, senior analyst at the Linley Group and senior editor of Microprocessor Report, sheds light on this benefit:

The ARMv8 instruction set is clean-slate approach with many improvements. Even without 4GB of RAM, the A7 should make it easier to build larger applications like PC-class games and programs. Apps can now become real desktop-class programs and games.

On top of that, the move to 64-bit enables developers to seamlessly port their 64-bit OS X apps to iOS 7.

John Gruber of Daring Fireball points to a blog post that compares Apple to Mercedes, to highlight the innovative work the company has done. He says: “Right now there’s only one iPhone that runs 64-bit code, has the M7 motion co-processor, shoots 120 FPS slow motion video, and has a Touch ID sensor. Two years from now, these will be standard features across the line.” And as Gruber summarizes Sisir Koppaka’s analysis of what we’ve seen this week during the iPhone event: Apple has been quiet recently, but what they’re doing is laying groundwork.

While Apple was the first to announce a 64-bit chip in a smartphone, its rival Samsung was quick to reply and say that it will make 64-bit smartphones as well. But the transition will likely take much more time, because there are more “moving pieces”, whereas on Apple’s side this seems to have been a seamless transition.