Thursday, December 3, 2015

The Success of ARM


What is fascinating is that Intel got into that position by being open, there were no fewer than 12 licensees for its 8086 design, and people had supplanted “expensive, proprietary lock-in” type architectures with more open and cheaper chips. It was the emergence of the PC market, and the great Chip Recession of 1984, where Intel decided if it was going to stay a chip maker, it had to be the best source of its dominant computer chips. I was at Intel at the time and it shifted from partnering, to competing, with the same people who had licensed its chips, with the intent of “reclaiming” the market for CPU chips for itself.


The relentless pace of putting more transistors into less space drove an interesting problem for ARM. When you get a process shrink you can do one of two things, you can cut your costs (more die per wafer), or you can keep your costs about the same and increase features (more transistors per die). And the truth is you always did a bit of both. But the challenge with chips is their macro scale parts (the pin pads for example) really couldn’t shrink. So you became “pad limited”. The ratio of the area dedicated to the pads (which you connected external wires too) and the transistors could not drop below the point where most of your wafer was “pad”. If it did so then you’re costs flipped and your expensive manufacturing process was producing wafers of mostly pads so not utilizing its capabilities.


So we had an explosion of “system on chip” products with all sorts of peripherals that continues to this day. And the process feature size keeps getting smaller, and the stuff added keeps growing. The ARM core was so small it could accommodate more peripherals on the same die, that made it cost effective and that made it a good choice for phones which needed long battery life but low cost.

Update (2015-12-03): mrpippy (via Twitter):

The advantages that Apple derives from the A-series SoCs is not due to any inherent advantage of ARM vs. x86, but because Apple has full control over the design and manufacturing.

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