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Apple Silicon

What Does It Mean For You? By Mark Wherry
Published December 2020

A slide from the WWDC keynote shows a high‑level architectural overview of Apple Silicon. That a high‑efficiency audio processor is included should raise eyebrows for readers of this magazine...A slide from the WWDC keynote shows a high‑level architectural overview of Apple Silicon. That a high‑efficiency audio processor is included should raise eyebrows for readers of this magazine...

Apple recently announced a transition in the Mac’s hardware architecture that promises to be the most significant in the product’s history. But how will this affect musicians and audio engineers?

“Let’s talk about transitions,” remarked Steve Jobs at the company’s annual Worldwide Developer’s Conference (WWDC) back in 2005. He was about to announce that, after much speculation, Apple would begin a two‑year process of replacing the PowerPC chips at the heart of the company’s Mac computers to those developed by rival chipmaker Intel. “Now, why are we going to do this?” quipped Jobs. “Isn’t the business great right now? Why do we want another transition?”

In recent years, there will undoubtedly have been those wary of contemplating such a question again. For some time, it’s been widely rumoured Apple would switch away from Intel processors to ARM‑based alternatives, similar to those used in the company’s other devices like the iPad. So when Tim Cook announced Apple would embark on another two‑year transition during this year’s WWDC keynote in June, re‑engineering Macs to be based on what the company is referring to as Apple Silicon, it was perhaps the least surprising surprise.

While it may seem like yesterday for long‑time Mac aficionados that Apple began the move from PowerPC to Intel processors, it’s worth remembering this was now 15 years ago. And the period since then has been the Mac’s longest relationship with a hardware architecture in the product’s 36‑year history. Apple’s original Macs were based around Motorola’s 68k family of chips (starting with the 68000 processor in 1984), and the final 68k Mac in production was 1995’s PowerBook 190 that used a 68LO040, which was a cheaper derivative of the 68040 due to the lack of a floating‑point unit!

The first PowerPC‑based Macs — the PowerMac 6100, 7100, and 8100s — were endowed with a PowerPC 601 processor and appeared in March 1994. And the final PowerPC was introduced 11 years later in November 2005, a PowerMac G5 that used the PowerPC 970MP chip, the first dual‑core PowerPC that was essentially two 970FX processors on a single piece of silicon.

Cook remarked that Apple still have some Intel‑based products in the pipeline, as we’ve seen with the recent 27‑inch iMac update. So we might not have seen the final Intel Mac just yet, since Apple have always released Macs that overlapped architectural transitions. Indeed, PowerPC‑based Macs were still shipping when Apple announced the first Intel‑based Macs in January 2006: the iMac and MacBook Pro, with Jobs noting “we’re kind of done with Power!”

This timeline shows the four hardware architectures used by the Mac since it was first introduced 36 years ago in 1984.This timeline shows the four hardware architectures used by the Mac since it was first introduced 36 years ago in 1984.

Why?

Apple transitioned to Intel not because PowerPC processors weren’t performant at the time — indeed, the Xbox 360 and the PS3 consoles both used one or more PowerPC cores to drive performance in the living room. Rather, Apple’s motivation was that Intel chips achieved better performance per Watt, allowing them to run cooler using less energy without sacrificing performance. And for the last 15 years, Intel’s processors have largely enabled Apple to introduce some pretty great products, such as the category‑defining MacBook Air, the aluminium iMacs and iMac Pro, and the latest Mac Pro.

The move to Apple Silicon is once again predicated largely by thermals, although this time for slightly different reasons due to the effective end of two laws in computer architecture and the implication of another: Moore’s law, Dennard scaling, and Amdahl’s law. And, at the risk of appearing sciolistic, it’s worth briefly noting the significance of these laws, and why their diminishment has led to Apple deciding the Mac’s need for such a radical brain transplant at this moment in its history.

Moore’s law is perhaps the best known of the three, named after Intel co‑founder Gordon Moore, stating that the number of transistors on a chip would double...

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Published December 2020