/// Apple’s iPhone 5s, the A7 Chip, and That 64-Bit Question

September 13, 2013  |  All Things Digital


When Apple unveiled the iPhone 5s on Tuesday, the company touted as one of its tentpole features the 64-bit desktop-class processing power of its new custom-made A7 chip. “The A7 is up to twice as fast as the previous-generation system at CPU tasks,” Apple marketing chief Phil Schiller said. “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.” According to Schiller, the A7 is “up to twice as fast” in raw processing power and graphics performance than its predecessor, the A6. And when paired with Apple’s forthcoming iOS 7 operating system — which has been designed with native 64-bit kernel, libraries and drivers — it provides unparalleled performance. “The benefits are huge,” Schiller said. “This is a huge leap forward.” And there’s no question that the benefits of 64-bit are huge. What’s less clear is how evident they’ll be in the iPhone 5s. Because, as innumerable observers have pointed out this week, in order to tap into the biggest performance gains offered by a 64-bit chip, you need a smartphone with more than four gigabytes of RAM . And, while Apple hasn’t said how much RAM it has built into the 5s, it’s highly unlikely that it’s enough to meet that requirement. That has led some to wonder whether this move to 64-bit is a long-term play whose only real short-term benefit is marketing — the ability to tout the 5s as the first 64-bit smartphone ever, even though it doesn’t have the internals to fully take advantage of that 64-bit A7 chip. But chip experts say that there are plenty of gains to had even from a 64-bit chip without 4GB of addressable memory. For one thing, 64 bit integer math will allow the A7 to execute operations much faster than the 32-bit A6. “The fact that the A7 has twice as many processor registers means that more operations can occur without the processor using main memory, which is slower to access,” Carl Howe, VP of research and data sciences at the Yankee Group told AllThingsD . “This means for that, for some codes, the A7 will be twice as fast (or faster, depending on how many memory accesses the original code had) to run code, because the processor doesn’t have to use main memory as much.” This should also improve battery life, as well. Another benefit: ARMv8, the architecture on which the A7 is likely based, has a very efficient instruction set that’s great for resource-intensive applications. As Kevin Krewell, senior analyst at the Linley Group and a senior editor of Microprocessor Report, told AllThingsD , “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.” The caveat here is that Apple must maintain backwards compatibility with legacy 32-bit apps until the 64-bit ecosystem really kicks in

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Apple’s iPhone 5s, the A7 Chip, and That 64-Bit Question


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