Apple A4 Processor in iPad, ARM’s or Apple’s?

by Mike Levin SEO & Datamaster, 02/17/2010

Yep, Apple’s Ax processors are RISC, rekindling the age-old issue, you thought was dead since x86 architecture won—and it’s back with a vengeance, revealing a super-rich history with Commodore roots.

[caption id=”” align=”alignright” width=”300” caption=”Image via Wikipedia”]DEC StrongARM SA-110 Microprocessor[/caption]

So the iPad has been announced and I have one more word to train my spell checker to know. I squinted at the cellphone video-feed trickling down UStream yesterday (re-published from, and hung on Job’s every word like a good fanboy. And I’ll be getting one.

But perhaps the most interesting aspect to me is the A4 processor, which is “Apple’s own silicon”. The historical backstory on this is fabulous. Apple is taking a page from Commodore’s history and owning their own suppliers, as with MOS Technologies and the 6502 chip, which powered the C64, Apple II, and many other computers of it’s day. Now, is it really an “Apple chip?” How much claim can they stake?

Apple bought a microprocessor company called P.A. Semi last year, consisting of people from Digital Equipment Corporation (DEC) who worked on the StrongArm processor. Most people’s explanation of how Apple could pull this off stops right here, but the story goes back much farther, and is much more interesting.

DEC was one of the biggest licensees of a technology called the ARM architecture, a low-power RISC CPU-type present in 90% of all smartphones. The “A” in ARM stands (stood) for Acorn, the “Apple of the United Kingdom” in the late 80’s. Acorn used the Commodore 6502 chip for their cheap computers, like everyone else in those days. The 6502, though rarely acknowledged as such, was actually one of the world’s first RISC processors, meaning it was cheaper due to fewer parts, and used less power. Still, it wasn’t perfect, and often needed supporting chips, particularly for sound and graphics. Two engineers from Acorn, dissatisfied with the graphics power of the 6502 researched alternatives, found none, and began designing their own.

They were successful, and in 1990 formed a company backed by Acorn, VLSI and… drumroll please… Apple to license this technology out to other companies, of which DEC was amongst the largest, with StrongArm. For legal reasons, DEC sold StrongArm to Intel in 1997, ironically making Intel one of the biggest ARM licensees. Ha ha ha. Intel subsequently renamed StrongArm as XScale until they sold it in 2006 to a company called Marvell Technology Group, of which I am a huge fan, and am carrying their SheevaPlug in my pocket right now.

Now remember, during all this, ARM the holding company did not produce any chips themselves—only licensees did, of which DEC was the largest, and most active in chip redesign and improvement. Now remember these DEC sharpies weren’t only licensing ARM, but they also are the same folks who brought us the DEC Alpha chip, a brief contender to Motorola and Intel for powerful personal workstation chips in those days. Enter P.A. Semi, the company Apple acquired. Guess who the are? Right! A bunch of folks from DEC and Intel, including the lead designer of the StrongArm.

It all comes around again, doesn’t it?

Against this same backdrop, Apple was not only a collaborator on ARM, but also was a big proponent of another RISC processor and a whole anti-Wintel movement called the AIM alliance, between Apple, IBM and Motorola. They ended up producing the PowerPC chip, and heir apparent to the popular 68000-series of chips that powered the original Macintosh’s. The PowerPC was used in subsequent generations of the Mac, sandwiched between the 680x0 days and the recent Intel days. Apple switched from RISC (reduced instruction set computers) to CISC (complex instruction set computers).

And so, the irony of yesterday’s announcement. Now that Apple is producing their own silicon, and it’s clearly something in the direct lineage of StrongArm, Apple is sitting on both sides of an age-old processor architecture war again, with Intel CISC-architecture in the Macintosh line, and ARM-architecture RISC in the iPhone, iPod and now iPad lines. But unlike in the previous days where RISC was bringing questionable value to a full-size desktop computer invoking nothing but unfair clock-speed comparisons with Mr. PC, this time around it should get the true benefit of the R in RISC, which stands for “reduced” which means efficiency—the kind of efficiency that’s absolutely critical in a powerful, yet low-power consumption device.

And yes, even though the ARM project which kicked off this whole alternative CPU story came from Acorn, the company that made it a reality was a collaboration between Acorn, Apple and VLSI. And exactly 20 years later, Apple goes back to that well, even though they’re a licensee like everyone else, it is in fact theirs in an even truer sense than MOS was Commodore’s.

Whereas Commodore forced the buy-out of an established CPU company, Apple enabled the creation of a brand-new processor, albeit inspired by the very 6502 processor in your old Commodore 64. So the iPhone, iPod and iPad are the step-grandchildren of the C64, and the resurgence of RISC with a vengeance.

I love these technology back-stories!

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