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Its okay, they'll switch ISA again in a few years then ARM will get parity with Intel in updates

Looking at the timeline (using announcement dates):

  1977      : 6502
  1984 (+ 7): 68000
  1994 (+10): PowerPC
  2005 (+11): x86
  2020 (+15): ARM

intervals between transitions creep up (I know those dates may not be the ones others would pick. I skipped the Apple 1 (1976), transition periods were sometimes long (they sold Apple 2’s up to 1993, etc))

Because of that I don’t see a next transition happen before around 2040.

If it happens my $0.02 is on riscv. That’s a big if, though. The main CPU is getting less and less relevant relative to custom accelerators, and they’re in control of their own instruction set, so they may be able to fix a few bottlenecks while (more or less) staying on ARM.

What could Apple possibly gain by switching to RISC-V? They already design their own ARM cores anyway so licensing isn’t an issue

In that timespan RISC-V could leapfrog ARM in overall performance (including power usage and price) -- who knows? Performance improvements have been a big driver of those previous migrations.

Apple could just buy up the world's capacity of the smallest node size process and build a faster chip with lower power draw, irrespective of whether ARM or RISC-V.

Apple didn’t migrate from PowerPC to Intel because Intel CPUs were way faster, there was just not a way for keeping with the demand and get new processors into the new cash drivers of the time, i.e. laptops.

It was essentially the same with Intel and Arm, plus the fact that they could save money and further integrate vertically.

Yes they did. You had fast PowerPC chips at the time, but they couldn't compete at power efficiency, which was important for consumer hardware, especially portable devices.

I'm confused. Of course Intel chips were better for laptops, that's exactly what I said.

That’s why I said “including power usage and price” above. IBM just weren’t able and/or willing to match Intel’s chips for Apple’s purposes.

(As I recall, but maybe I misremember, Apple claimed a big performance advantage for their high-end G5 Macs but in the real world it was a bit dubious.)

That could happen for ordinary people and companies who have to rely on commodity processors or who license ARM cores and add their own peripherals around them on a custom chip, but Apple designs their own ARM processors.

They have an ARM architecture license. They design their own ARM implementations from the ground up.

If something can be done to RISC-V designs that would leapfrog ARM and ARM does not want to incorporate whatever breakthrough that is into their own cores for some reason that will mean that the people who rely on commodity ARM chips or on licensed ARM cores will be out of luck.

Apple on the other hand would be free to incorporate that into their ARM implementation.

> RISC-V could leapfrog ARM in overall performance

RISC-v is an instruction set. If any company made a better RISC-v core than Apple can make themselves they could either buy it from them or make their own faster ARM core.

That’s what happened with Intel and PowerPC…

What improvements in the instruction set itself could make RISC-v fundamentally faster than equivalent ARM chips?

Calling 15 years “a few” is a tad dramatic.

I don't think it'll take 15 years for RISC-V processors to be competitive with ARM.

What’s the point if they’re merely competitive? There has to be some compelling advantage - why would Apple throw out their ARM ISA for RISC-V. Unlike other companies the licensing isn’t really an issue.

Well, Apple already designs their own processors; the math also works out for them to cut out the middleman with ARM if you disregard their Softbank relationship. They don't rely on Cortex designs like Qualcomm and they already have extended the ISA for their own purposes. It appears that Apple could stand to benefit from an ISA they can truly control. Whether it's worth another transition is unclear, but Apple's desire for control over their digital supply chain is obvious. It's not like you can argue that they can't pull off a RISC transition, either.

Hoe much are they even paying ARM?

> It's not like you can argue that they can't pull off a RISC transition

Apple could also possibly send a spaceship to the moon if they really wanted to. Not sure there are any practical reasons to do that.

They’ve been working on ARM chips for almost a decade to get to where they are now. Throwing that away for some ill defined advantages seems not that rational.

> Hoe much are they even paying ARM?

I think Apple has a perpetual license to ARM tech because they put up a bunch of investment money after ARM spun off from Acorn.

The perpetual license to ARM ISA has nothing to do with Apple's investment into ARM or Acorn. Anyone with money could buy a perpetual license to its ISA under the condition ARM and buyer agree with.

A RISC transition and a moon landing are markedly different things, though. They've already migrated MacOS to a RISC architecture, whereas nothing Apple makes is really intended to go into space. Unlike building a rocket ship, we already know Apple can do this.

None of us really know the specifics of Apple's deal, though. It's a perpetual license and they are in-bed with the firm that majority-owns ARM. It seems like a good deal, but obviously it's not good enough; Apple doesn't use any ARM-provided core designs and even adds their own ISA extensions when-needed. They themselves are using ARM like it is RISC-V, and they're a big enough stakeholder that they can get away with it.

> They’ve been working on ARM chips for almost a decade

https://appleinsider.com/articles/21/09/03/apple-investigati...

They've been exploring RISC-V internally for a couple years now, too.

I think it is either extremely foolish or ignorant to think that RISC-V won't undermine most ARM-licensed devices. The vast majority of places where ARM is used (even in Apple devices) is small and cheap microcontrollers that mostly cost whatever their license demands. If Apple could switch their internal ICs to RISC-V, they would already be saving a lot of money without transitioning to RISC-V fully.

> They've already migrated MacOS to a RISC architecture,

Have they?

I certainly think you have a point about microcontrollers.

I find it very doubtful RISC-v would supplant ARM on the high end anytime soon. The licensing fees are pretty peanuts compared to the cost of designing your own cores and even the big players have been struggling to come up with anything that could compete against ARMs designs (besides Apple of course).

Also it’s not at all clearer what incentives would Apple have to switch to RISC-V? Sure they could do it.. what would they gain though?

That’s true, but at the same time, throwing out their ARM ISA wouldn’t necessarily be a huge cost for them; they’ve migrated smoothly a bunch of times in the past, so they’re really good at it.

If there were a compelling advantage at some point, they could go for it.

Knowing Apple, their next move is probably going to be inventing an ISA out of whole cloth; either that or acquire RISC-V International, so that they can be sure that future ISA changes and developments support their needs first.

They already invented an ISA, it's called ARMv8. The ISA was designed for Apple Silicon, not the other way round.

You're right, it'll sadly be a lot longer.

It felt like less time because most of Apple's devices (nearly everything that wasn't a mac) already ran ARM in the interim.

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