ARM processors were still trapped in desktop business computers when researchers at Apple first discovered them. Mobius, a research project on ARM2 emulating both the Apple II and Macintosh on a single platform, was shelved due to marketing nightmares. However, LISP on ARM2 was found to be extremely fast. Later, at a critical point in Newton development when it appeared its AT&T Hobbit processor would never work, Apple took the bold step of helping create a joint venture in late 1990: Advanced RISC Machines Holdings Limited, what we know today as ARM Holdings plc.

ARM’s first major new project was the ARM610, with samples delivered to Apple after only 11 months of development by October 1991. Many improvements from the Apple wish list had been incorporated into a power-efficient static design, including full 32-bit addressing (increased from 26-bit addressing in prior ARM implementations) and a new memory management unit. The ARM610 was a standard microprocessor product sold to multiple customers, but its success marked the beginning of a long, productive mobile SoC partnership between Apple and ARM.

When Steve Jobs returned to Apple in 1997, he quickly squashed the Newton and set his sights on more elegant devices designed more for consumer tastes. The first of these was the iPod, released in 2001 with an ARM-based MP3 decoder chip from PortalPlayer. Combined with an updated iTunes release supporting synchronization with a Mac, the iPod was a smash hit. The iPod nano debuted at a lower price point with Samsung flash inside in early 2005.

Samsung was also developing MP3 decoder chips, and its new S5L8701 SoC won over Apple for future iPods in April 2006. The Samsung-Apple partnership deepened with the introduction of the iPhone in January 2007. Inside was the S5L8900, labeled APL0098 for Apple. The Samsung S5L8920, labeled as the Apple APL0298, appeared in the iPhone 3GS in June 2009.

From there, Apple took over chip design with an ASIC team bolstered by the acquisition of P. A. Semi. It signed an architecture license with ARM in late 2008, embarking on its first internal SoC design. Instead of developing its own ARMv7-compliant core, Apple elected to use the Intrinsity “Hummingbird” core, already on a Samsung 45nm process, and created the A4 chip. Launched first in the iPad in January 2010, the A4 also powered the iPhone 4 in June 2010. Furthering its SoC efforts, Apple acquired Intrinsity in March 2010.

What followed was a set of alternating volleys of tables and phones, each subsequent generation with a new Apple SoC. The line bifurcated with the A5 in the iPhone 4s and the A5X, enhanced for tablets with a 128-bit memory interface, in the iPad 3rd gen. After using a stock ARM Cortex-A9 core in the A5, Apple moved to its own custom core design “Swift” for the A6 and A6X, on a faster Samsung 32nm process. In 2013, the A7 went to a 64-bit implementation of ARMv8-A, dubbed “Cyclone”, and moved to TSMC for fabrication. The A8 and A8X appeared in 2014 with “Typhoon” cores shrunk to TSMC 20nm.

In 2015, Apple went to dual sourcing for the A9 chip with its “Twister” cores, some from TSMC on 16nm, and some from Samsung on 14nm FinFET. The A9X debuted for the holiday season on the iPad Pro. With enormous volumes, Apple now dominates the foundry business and is in effect a fabless semiconductor firm. The news to watch will be how the foundry business keeps up as Apple and others run into the 10nm process cauldron in 2016 and beyond.

For more history on Apple mobile SoCs and devices, read the full-length book “Mobile Unleashed: The Origin and Evolution of ARM Processors In Our Devices”.

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