There have been rumors suggesting Apple has an interest in Arm-based Macsfor years now, but speculation about an Arm-based Mac has picked up over the course of the last year following rumors about Apple's work on its own chips designed for the Mac.

Apple is currently reliant on Intel for the processors used across its Mac lineup, but that is perhaps set to change in the future as Apple works to transition over to Arm-based chips similar to the A-series chips used in its iPhones and iPads. Apple could unveil its Arm-based Mac plans at WWDC 2020  with the new Macs set to debut starting in 2021.

Arm vs. Intel

Right now, Apple uses x86 chips from Intel in all of its Mac products, while its iPhones and iPads use Arm-based chips. x86 chips and Arm chips are built using different architectures.

Intel's chips are CISC (Complex Instruction Set Architecture) while Arm chips are RISC (Reduced Instruction Set Computer).
Were Apple to switch from CISC Intel chips to RISC it would likely have a positive impact on power efficiency and compute efficiency for everyday users because most people don't use applications that take advantage of the more complex instructions of a CISC chip. 

A chip instruction set can be likened to different words in the English language that mean the same thing. As an example, someone might use the word "hit" multiple times in a day, but would rarely find a reason to use the word "pummel." An RISC chip in this scenario only knows the word "hit," while a CISC chip knows the word "pummel." When there's a call for the "hit" instruction to be made multiple times, the RISC chip would need to use multiple "hit" instructions, while the CISC chip can more efficiently call up the "pummel" instruction instead. 

Because most people don't need to use "pummel" often, the RISC chip is, overall, more efficient for day to day use. For pro users, though, the CISC chip may be more the more efficient choice.

Ditching Intel

Apple has been using Intel's chips in its Mac lineup since 2006 after transitioning away from PowerPC processors. Because Apple is using Intel technology, Apple is subject to Intel's release timelines and chip delays.

Over the course of the last several years, there have been multiple instances where Intel has seen significant chip delays that have undoubtedly impacted Apple's product plans. Swapping over to its own house-made chips would allow Apple to release updates on its own schedule and with perhaps more frequent technology improvements.

Apple would also be able to differentiate its devices from competing products with chips designed by its own internal teams, introducing even tighter integration between hardware and software.

Apple's Arm-Based Chips for iOS Devices

Apple uses an Arm-based architecture for its A-series chips in the iPhone and iPad and each year, those chips get faster and more efficient. In fact, when introducing the latest A12 and A13 chips, Apple has made it a point to emphasize that these chips are faster than many Intel-based chips in competing devices.

The 2018 and 2020 iPad Pro  models with A12X and A12Z chips, for example, are close in speed to the 2018 15-inch MacBook Pro  models.

With Apple closing the speed gap between Arm and x86, there's no reason why many of the company's notebook machines (and even desktop machines) couldn't be powered by Arm-based chips instead of standard Intel chips.

Apple's A-series chip packages also include custom-built GPUs, Secure Enclave, memory and storage controllers, machine learning processors, Image Signal Processing, custom encryption, and more, all of which could also be applied to Mac processors.

Arm Chips in Current Macs

The ‌MacBook Pro‌, MacBook Air , iMac Pro, Mac Mini and Mac Pro are already equipped with Arm processors, in the form of the T1 and T2 chips that power the Touch Bar and other features in these machines.

The T2 chip in particular integrates several components, including the system management controller, image signal processor, SSD controller, and a Secure Enclave with a hardware-based encryption engine in addition to powering the Touch Bar and Touch ID.

Arm Benefits

Bringing Arm chips to a Mac could bring efficiency and battery life improvements without sacrificing speed, with Apple also perhaps able to cut down on the size of some of the internal components, thus perhaps allowing for slimmer devices.

Arm-based chips will feature multiple advantages over Intel-based Macs, such as faster performance and reduced power consumption. Macs with Apple-designed chips will show gains in graphics performance and apps using artificial intelligence.

Apple's Rumored Work on Arm-Based Chips

Rumors suggest that Apple employees are working on an initiative  codenamed "Kalamata" to make iPhones, iPads, and Macs work more seamlessly together. One aspect of this involves new custom-built Mac chips that are designed by Apple much like its current ‌iPhone‌ and ‌iPad‌ chips.

Apple eventually wants developers to be able to create apps that can run across all Apple devices, and along with custom-built chips, Apple has also been working on this on the software side with Mac Catalyst. Mac Catalyst lets developers port their ‌iPad‌ apps over to the Mac App store with minimal effort.

Apple will provide the first details on its secretive work on Arm-based chips at the virtual ‌WWDC 2020‌ event.

Multiple Arm-Based Chips in the Works

According to Bloomberg, Apple is developing at least three  Mac processors that are based on the A14 chip in the upcoming iPhone 12 models. 

At least one of the three processors will be much faster than the A-series chips in iPhones and iPads, and the first Mac processors will feature 12 cores, including eight high-performance cores and at least four energy-efficient cores. 

Apple is also already working on a second generation of Mac processors based on the A15 chip, which could have more than 12 cores.

The First Arm-Based Mac?

For the first Arm-based Mac, leaker Fudge (@choco_bit on Twitter) believes that Apple could revive  the discontinued 12-inch MacBook, which could look the same as the retired version. We haven't heard from any other sources which Mac might be the first to get a custom Apple chip.

When Will Apple Release an Arm-Based Mac?

Apple is expected to announce  its planned shift to Arm-based Macs at WWDC, providing some insight into its efforts to transition away from Intel chips to chips made in-house. Apple plans to announce Arm-based chips early to give developers time to prepare for the change, but the first Arm-based Macs won't be coming right away.

Apple could, however, give us some insight into which Macs will be getting Arm chips first, with rumors suggesting Apple plans to bring its custom designed chips to its entire Mac lineup in the future.

There have been some mixed rumors on when Apple could launch the first Arm-based Macs. Apple analyst Ming Chi Kuo believes Apple will release  MacBook models with its own custom processors in the fourth quarter of 2020 or the first quarter of 2021.

Kuo expects Apple to release  several Mac notebooks and desktop computers with custom designed Arm-based processors in 2021, so the custom processors won't be limited to just one machine. 

Bloomberg has said that Apple is aiming to release at least one Mac with a custom-designed Arm-based processor by 2021.