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0 pointsAnIrishDuck10y ago0 comments

> Apple isn't dependent on anyone for ship dates in the ARM space -- they license the ISA, but they design their own chips based on the license. [...] I don't see how replacing ARM with a custom ISA helps Apple any.

Well, what if the time comes when ARM cannot deliver processor designs with necessary improvements to power consumption or processing speed? If they hit that wall, a new processor architecture might be the only way forward.

Given Apple's resources and position, that kind of contingency planning makes sense to me. You can't exactly spin up a architecture design team overnight.

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Narishma10y ago

Apple doesn't use ARM's processor designs. They just license the ISA and design their own CPUs.

AnIrishDuckOP10y ago

True, but the basic point still stands. ISA heavily constrains the final design on-die. ARM might not be able to deliver an ISA that fits Apple's needs.

Apple already has a tweaked version of ARM (ARMv7s) [1]. There may come a day where tweaks no longer cut it. At the end of another excellent post, from the same author [2]:

> If compiler–architecture co-design is on the table, much more radical opportunities are available.

Apple has both compiler and architecture teams. And if it sees ties to a specific architecture hurting its product development goals again? It seems like exactly the kind of company that would drop the ARM ISA completely.

Or at least like the kind of company that wants to keep that option on the table.

[1] http://www.linleygroup.com/newsletters/newsletter_detail.php... [2] http://adriansampson.net/blog/macroscalar.html

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