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RISC vs. CISC Is the Wrong Lens for Comparing Modern x86, ARM CPUs


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Comparing x86 and ARM CPUs.

ARM may prominently identify itself as a RISC CPU company, but today these terms conceal as much as they clarify regarding the modern state of x86 and ARM CPUs.

Credit: ESA Automation

With Apple's WWDC coming up soon, we're expecting to hear more about the company's updated, ARM-based MacBook Pro laptops. Rumors point to Apple launching a slate of upgraded systems, this time based around its "M2" CPU, a scaled-up version of the M1 core that debuted last year. The M2 could reportedly field eight high-performance cores and two high-efficiency cores, up from a 4+4 configuration in the existing M1.

With the launch of the ARM-based M1 came a raft of x86-versus-ARM comparisons and online discussions comparing and contrasting the new architectures. In these threads, you'll often see authors bring up two additional acronyms: CISC and RISC. The linkage between "ARM versus x86" and "CISC versus RISC" is so strong, every single story on the first page of Google results defines the first with reference to the second.

This association mistakenly suggests that "x86 versus ARM" can be classified neatly into "CISC versus RISC," with x86 being CISC and ARM being RISC. Thirty years ago, this was true. It's not true today. The battle over how to compare x86 CPUs to processors built by other companies isn't a new one. It only feels new today because x86 hasn't had a meaningful architectural rival for nearly two decades. ARM may prominently identify itself as a RISC CPU company, but today these terms conceal as much as they clarify regarding the modern state of x86 and ARM CPUs.

From ExtremeTech
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