Apple’s Ax Chronicle

In April 2008, Apple baffled the semiconductor industry by acquiring the system-on-chip (SoC) pioneer PA Semi for US$278 million. The acquisition, took place at the height of the iPhone fever, left the technology and trade media with an endless suite of guessing games. In the end, it was just about Apple’s quest for having better chips for the mobile devices.

PA Semi co-founder, Dan Dobberpuhl, was a pioneer in microprocessor design and had contributed to the landmark T-11, Alpha and StrongARM processor developments at DEC. After leaving DEC in 1998, He had founded SiByte, which developed the first multicore SoC device and was later sold to Broadcom for US$2 billion.

When Apple unveiled the iPad in January 2010, Steve Jobs specifically called A4 the best and most complicated chip that Apple had ever designed. Initially, industry observers perceived the A4 as just another SoC that hooked up various IPs available from different companies. But then in April 2010, The New York Times reported that Apple has acquired the Austin, Texas-based chipmaker Intrinsity for an undisclosed amount.

That was about the time when people in the semiconductor industry connected the dots and began to understand Jobs’s claim of Apple’s long-term processor strategy for the iPhone and iPad. The story about the making of Apple’s first in-house SoC goes back to September 2008 when Samsung inked a deal with chip design house Intrinsity to develop a FastCore version of the Cortex-A8 which they called as Hummingbird. Meanwhile, Apple was looking for a way to speed up the Cortex-A8 CPU for its upcoming iPad.

According to some industry reports, Samsung asked Intrinsity to develop a FastCore version of the Cortex-A8 for Apple’s for A4 while utilizing it for its S5PC110 and S5PV210 chips after splitting the cost. Hummingbird was a ground-up, cycle-accurate, high-performance remake of ARM’s Cortex A8 architecture to get the CPU core’s clock speed comfortably up to 1GHz. The ARM-based small chip shop from Texas had brought to Apple that PA Semi couldn’t: a CPU core.

Apple A4 SoC: In January 2010, Apple introduced the A4 chip manufactured at 45nm process; it incorporated clock speed and RAM data bus enhancements that enabled it to drive the increased resolution of iPad. The A4 chip combined a single Cortex A8 CPU core to a single-core PowerVR SGX 535 GPU and either 256MB or 512MB of RAM. Apple also put the A4 chip in iPhone 4 and Apple TV.

Apple A5 SoC: In March 2011, when Apple introduced the more powerful iPad 2 device, it was powered by the dual-core A5 chip that featured twice the CPU power and eight times the GPU performance of the A4 chip. The A5 chip married a dual-core Cortex A9 CPU with a dual-core PowerVR SGX 543MP2 GPU and 512MB of RAM. It was subsequently used in the iPhone 4S handset and the iPad with Retina Display.

Apple A6 SoC: in September 2012, Apple shipped iPhone 5 with A6, a new chip featuring an entirely custom “Swift” core design and manufactured at 32nm process. The A6 SoC married two of Apple’s custom-designed Swift CPU cores to a triple-core PowerVR SGX 543MP3 GPU and 1GB of RAM, roughly doubling the performance of the A5 in every respect. The most striking feature of A6 SoC was the in-house designed CPU: Swift.

Apple A7 SoC: In September 2013, nearly three years of releasing its first custom A4 chip, Apple launched the first 64-bit ARMv8 A7 chip using an entirely new Cyclone core design and a 28nm process. Apple, now a competitive chip designer, made a shift from Swift CPU core to Cyclone CPU core, which made the A7 chip look more like a desktop processor. The Cyclone CPU architecture had made a leap forward from small core CPUs commonly used in mobile devices to large core CPU found in desktop computers.

Apple A8 SoC: The semiconductor industry was still coming to terms with the wonders of 64-bit computing that Apple had showcased in the form of A7 chip when Apple took another leap of faith in the SoC religion. The Cupertino-based computing giant announced the second 64-bit chip called A8 at the launch of iPhone 6 and iPhone 6 Plus on September 9, 2014.

A prominent highlight in the launch of A8 chip was Apple’s move away from Samsung’s fab to TSMC, something widely anticipated in the industry amid Apple’s increasingly complicated relationship with Samsung. The A8 SoC was about 25 percent faster than its predecessor in CPU tasks and 50 percent faster on the GPU side of things. It was also 50 percent more power efficient than the A7, and despite almost doubling the transistor count, the die size was nearly 13 percent smaller.

Majeed Ahmad is author of books Smartphone: Mobile Revolution at the Crossroads of Communications, Computing and Consumer Electronicsand The Next Web of 50 Billion Devices: Mobile Internet’s Past, Present and Future.

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