The iPhone 5 has the A6 CPU, which industry experts say is the first in a line of many upcoming Apple custom processors that will better balance performance with battery life in iPhones and iPads.
The custom-designed A6 core is a big step for Apple, whose previous A4 and A5 processors for iPhones and iPads were based on designs adopted from ARM. The A6 is also based on ARM architecture, but after analysing code, chip size and the architecture, experts have concluded that Apple has designed its own CPU from the ground up rather than licensing an existing processor design.
It took a few years for Apple to customise its own CPU, but the company wants to control its own destiny, experts said. The new chip gives Apple top-to-bottom control over its smartphones and tablets, and ensures that the CPU and applications perform in tandem while preserving battery life in devices.
Apple will likely continue to custom-design its own CPUs for iPhones, iPads and other devices, the experts said. But Apple will face challenges in a few years as chips get smaller and integrate radios and other components, which may require further investments.
Apple has been quiet on details about the new chip, but has said A6 delivers twice the performance compared to the A5 processor. The iPhone 5 delivers 150% more performance than the predecessor 4S, which had an A5 processor based on a Cortex-A9 design, according to iFixit, a computer repair firm that did a teardown of the iPhone 5 shortly after it was released last week.
Anand Shimpi, who runs the tech site Anandtech, was the first to suggest that iPhone 5 has a custom core. He said the new phone is faster than the 4S, but he didn't have many details. He plans to publish benchmarking numbers and other details in the coming days.
Shimpi expects Apple to continue to tailor chips to balance application performance and battery life on smartphones and tablets. A6 is based on the existing ARMv7 architecture and has a new floating point core, he said.
"Apple knows exactly what they want to do. They can deliver performance when they know they have applications that need it," Shimpi said.
Apple is committed to increasing performance but is very particular about battery life, even if it has to lower the clock speed of a CPU, said Linley Gwennap, founder and principal analyst at The Linley Group, which analyzes and benchmarks chip performance. Based on certain chip parameters, The Linley Group earlier this week also said it thought the A6 has a custom CPU.
"I wouldn't be surprised if they put A6 in the iPad," Gwennap said. Apple could just crank up the clock speed and put it in the iPad to take advantage of the larger battery in the tablet.
It's possible that Apple will ultimately design a custom ARM-based CPU for Mac laptops, but will perhaps wait two years for ARM's 64-bit architecture, Gwennap said. ARM processors are currently 32-bit and cannot address more than 4GB of memory, while Mac laptops need 64-bit architecture and the capability to address more memory. ARM has already announced the ARMv8 64-bit architecture and expects devices like smartphones and tablets based on the architecture to start shipping in 2014.
But the chip industry moves at a fast pace, and Apple is taking on more responsibility with custom processor design. Right now, the iPhone 5 has a separate CPU and baseband chip, but will have to keep up with Qualcomm, which already offers a Snapdragon S4 dual-core chip with an integrated radio, and Nvidia, which is on its way to integrating software-defined radios in future Tegra chips.
The company has to tweak chip designs or microarchitectures to keep pace with advancements in manufacturing process technology, much like Intel's tick-tock strategy, which advances chip technology in line with the manufacturing process, Anandtech's Shimpi said. It appears that the A6 chip may be made by Samsung based on the 32-nanometre process, he guessed.
Contract chip manufacturer TSMC (Taiwan Semiconductor Manufacturing Co.) is already making chips with the 28nm process, and GlobalFoundries this week said it will start making chips using the 20nm process in 2013 and the 14nm process in 2014.
Gwennap said that Apple has able chip leadership in Peter Bannon, an Apple director who came to the company with the 2008 acquisition of PA Semi, and Gerard Wallace, an ARM fellow who was one of the leaders in the team that developed the Cortex-A8 and Cortex-A15 CPU. Apple's former platform architect Jim Keller was recently hired away by Advanced Micro Devices to run the processor division.
"They've been hiring like crazy," Gwennap said of Apple. "They have the ability to bring in the people they need."