As you may have seen, I sent the following Tweet: “The Apple ARM MacBook future is coming, maybe sooner than people expect” https://twitter.com/choco_bit/status/1266200305009676289?s=20
Today, I would like to further elaborate on that. tl;dr Apple will be moving to Arm based macs in what I believe are 4 stages, starting around 2015 and ending around 2023-2025: Release of T1 chip Macbooks, release of T2 chip Macbooks, Release of at least one lower end model Arm Macbook, and transitioning full lineup to Arm. Reasons for each are below.
Apple is very likely going to switch to switch their CPU platform to their in-house silicon designs with an ARM architecture. This understanding is a fairly common amongst various Apple insiders. Here is my personal take on how this switch will happen and be presented to the consumer.
The first question would likely be “Why would Apple do this again?”. Throughout their history, Apple has already made two other storied CPU architecture switches - first from the Motorola 68k to PowerPC in the early 90s, then from PowerPC to Intel in the mid 2000s. Why make yet another? Here are the leading reasons:
- Intel has, in recent years, been making significant losses both in reputation and in actual product value, as well as velocity of product development, breaking their bi-yearly “Tick Tock” cycle for the first time in decades. Most recently, they have fallen well behind AMD’s processor lines in cost to performance ratio, CPU core count, core design (monolithic design vs “chiplet”), power consumption to performance, silicon supply (Intel with significant manufacturing process and yield issues), and on-silicon security features. While Intel still wins out in certain enterprise and datacenter applications, as well as having a much better reputation for reliability and QA (AMD having shipped numerous chips with a broken random- number generator that prevented even booting some mainstream operating system), the number of such applications slowly dwindles with each new release from AMD, and as confidence among decisionmakers in enterprise increases. In the public consciousness, Intel is quickly becoming a point of ridicule against Apple’s Mac lineup, rather than a badge of honor.
- By moving to their own designs, Apple will be free from Intel’s release schedule, which have recently been unpredictable and faced with routine delays due to poor manufacturing yields. Apple will be able to update their Mac lineup on their own timeline, rather than being forced to delay products based on Intel’s ability to meet the release window. This also allows them to leverage relationships with other silicon fabricators to source chips, rather than relying on Intel ’s continued “iteration” that’s leading to a “14nm++++++++++” process, or the continued lack of product diversity with the 10nm process. Apple will also be free to innovate in the design of the silicon platform, rather than being limited by Intel’s design choices. By having full control of the manufacturing and development cycle, Apple can bring even more in-house optimization to the macOS, as they have been for iOS and iPadOS over the years.
- Using an ARM architecture on the Macs allows for a more unified Apple ecosystem, rather than having separate Mac and iOS-based products. The only distinction will be the device form factor and performance characteristics.
- The x86_64 architecture is very old and inefficient, using older methodologies for processor design (CISC vs ARM’s RISC), and the instruction set continues to require support in silicon for emulating 1980s-vintage 16-bit modes, as well as ineffectual and archaic memory addressing modes (segmentation, etc.) The x86_64 architecture is like a city, built atop a much older city, built atop a yet older city, but every layer is built with NYC infrastructure levels of complexity that suited its time and no further.
- Over the last 10 years, Apple has shown that they can consistently produce impressive silicon designs, often leading the market in performance and capability, and Apple has been aggressively acquiring silicon design talent.
A common refrain heard on the Internet is the suggestion that Apple should switch to using CPUs made by AMD, and while this has been considered internally, it will most likely not be chosen as the path forward, even for their megalithic giants like the Mac Pro. Even though AMD would mitigate Intel’s current set of problems, it does nothing to help the issue of the x86_64 architecture’s problems and inefficiencies, on top of jumping to a platform that doesn’t have a decade of proven support behind it. Why spend a lot of effort re-designing and re- optimizing for AMD’s platform when you can just put that effort into your own, and continue the vertical integration Apple is well-known for?
I believe that the internal development for the ARM transition started around 2015/2016 and is considered to be happening in 4 distinct stages. These are not all information from Apple insiders; some of these these are my own interpretation based off of information gathered from supply-chain sources, examination of MacBook schematics, and other indicators from Apple.
Stage1 (from 2014/2015 to 2017):
The rollout of computers with Apple’s T1 chip as a coprocessor. This chip is very similar to Apple’s T8002 chip design, which was used for the Apple Watch Series 1 and Series 2. The T1 is primarily present on the first TouchID enabled Macs, 2016 and 2017 model year MacBook Pros.
Considering the amount of time required to design and validate a processor, this stage most likely started around 2014 or 2015, with early experimentation to see whether an entirely new chip design would be required, or if would be sufficient to repurpose something in the existing lineup. As we can see, the general purpose ARM processors aren’t a one- trick pony.
To get a sense of the decision making at the time, let’s look back a bit. The year is 2016, and we're witnessing the beginning of stagnation of Intel processor lineup. There is not a lot to look forward to other than another “+” being added to the 14nm fabrication process. The MacBook Pro has used the same design for many years now, and its age is starting to show. Moving to AMD is still very questionable, as they’ve historically not been able to match Intel’s performance or functionality, especially at the high end, and since the “Ryzen” lineup is still unreleased, there is absolutely no benchmarks or other data to show they are worth consideration, and AMD’s most recent line of “Bulldozer” processors were very poorly received. Now is probably as good a time as any to begin experimenting with the in-house ARM designs, but it’s not time to dive into the deep end yet, our chips are not nearly mature enough to compete, and it’s not yet certain how long Intel will be stuck in the mud. As well, it is widely understood that Apple and Intel have an exclusivity contract in exchange for advantageous pricing. Any transition would take considerable time and effort, and since there are no current viable alternative to Intel, the in-house chips will need to advance further, and breaching a contract with Intel is too great a risk. So it makes sense to start with small deployments, to extend the timeline, stretch out to the end of the contract, and eventually release a real banger of a Mac.
Thus, the 2016 Touch Bar MacBooks were born, alongside the T1 chip mentioned earlier. There are good reasons for abandoning the piece of hardware previously used for a similar purpose, the SMC or System Management Controller. I suspect that the biggest reason was to allow early analysis of the challenges that would be faced migrating Mac built- in peripherals and IO to an ARM-based controller, as well as exploring the manufacturing, power, and performance results of using the chips across a broad deployment, and analyzing any early failure data, then using this to patch any issues, enhance processes, and inform future designs looking towards the 2nd stage.
The former SMC duties now moved to T1 includes things like
- Fan speed, voltage, amperage and thermal sensor feedback data
- FaceTime camera and microphone IO
- PMIC (Power Management Controller)
- Direct communication to NAND (solid state storage)
- Direct communication with the Touch Bar
- Secure Enclave for TouchID
The T1 chip also communicates with a number of other controllers to manage a MacBook’s behavior. Even though it’s not a very powerful CPU by modern standards, it’s already responsible for a large chunk of the machine’s operation. Moving control of these peripherals to the T1 chip also brought about the creation of the fabled BridgeOS software, a shrunken-down watchOS-based system that operates fully independently of macOS and the primary Intel processor.
BridgeOS is the first step for Apple’s engineering teams to begin migrating underlying systems and services to integrate with the ARM processor via BridgeOS, and it allowed internal teams to more easily and safely develop and issue firmware updates. Since BridgeOS is based on a standard and now well-known system, it means that they can leverage existing engineering expertise to flesh out the T1’s development, rather than relying on the more arcane and specialized SMC system, which operates completely differently and requires highly specific knowledge to work with. It also allows reuse of the same fabrication pipeline used for Apple Watch processors, and eliminated the need to have yet another IC design for the SMC, coming from a separate source, to save a bit on cost.
Also during this time, on the software side, “Project Marzipan”, today Catalyst, came into existence. We'll get to this shortly.
For the most part, this Stage 1 went without any major issues. There were a few firmware problems at first during the product launch, but they were quickly solved with software updates. Now that engineering teams have had experience building for, manufacturing, and shipping the T1 systems, Stage 2 would begin.
Stage 2 encompasses the rollout of Macs with the T2 coprocessor, replacing the T1. This includes a much wider lineup, including MacBook Pro with Touch Bar, starting with 2018 models, MacBook Air starting with 2018 models, the iMac Pro, the 2019 Mac Pro, as well as Mac Mini starting in 2018.
With this iteration, the more powerful T8012 processor design was used, which is a further revision of the T8010 design that powers the A10 series processors used in the iPhone 7. This change provided a significant increase in computational ability and brought about the integration of even more devices into T2. In addition to the T1’s existing responsibilities, T2 now controls:
- Full audio subsystem
- Secure Enclave for internal NAND storage and encryption/decryption offload
- Management of the whole system’s power and startup sequence, allowing for trusted boot (ensure boot chain-of-trust with no malicious code/rootkit/bootkit)
Those last 2 points are crucial for Stage 2. Under this new paradigm, the vast majority of the Mac is now under the control of an in-house ARM processor. Stage 2 also brings iPhone-grade hardware security to the Mac. These T2 models also incorporated a supported DFU (Device Firmware Update, more commonly “recovery mode”), which acts similarly to the iPhone DFU mode and allows restoration of the BridgeOS firmware in the event of corruption (most commonly due to user-triggered power interruption during flashing).
Putting more responsibility onto the T2 again allows for Apple’s engineering teams to do more early failure analysis on hardware and software, monitor stability of these machines, experiment further with large-scale production and deployment of this ARM platform, as well as continue to enhance the silicon for Stage 3.
A few new user-visible features were added as well in this stage, such as support for the passive “Hey Siri” trigger, and offloading image and video transcoding to the T2 chip, which frees up the main Intel processor for other applications. BridgeOS was bumped to 2.0 to support all of these changes and the new chip.
On the macOS software side, what was internally known as Project Marzipan was first demonstrated to the public. Though it was originally discovered around 2017, and most likely began development and testing within later parts of Stage 1, its effects could be seen in 2018 with the release of iPhone apps, now running on the Mac using the iOS SDKs: Voice Recorder, Apple News, Home, Stocks, and more, with an official announcement and public release at WWDC in 2019. Catalyst would come to be the name of Marzipan used publicly. This SDK release allows app developers to easily port iOS apps to run on macOS, with minimal or no code changes, and without needing to develop separate versions for each. The end goal is to allow developers to submit a single version of an app, and allow it to work seamlessly on all Apple platforms, from Watch to Mac. At present, iOS and iPadOS apps are compiled for the full gamut of ARM instruction sets used on those devices, while macOS apps are compiled for x86_64. The logical next step is to cross this bridge, and unify the instruction sets.
With this T2 release, the new products using it have not been quite as well received as with the T1. Many users have noticed how this change contributes further towards machines with limited to no repair options outside of Apple’s repair organization, as well as some general issues with bugs in the T2.
Products with the T2 also no longer have the “Lifeboat” connector, which was previously present on 2016 and 2017 model Touch Bar MacBook Pro. This connector allowed a certified technician to plug in a device called a CDM Tool (Customer Data Migration Tool) to recover data off of a machine that was not functional. The removal of this connector limits the options for data recovery in the event of a problem, and Apple has never offered any data recovery service, meaning that a irreparable failure of the T2 chip or the primary board would result in complete data loss, in part due to the strong encryption provided by the T2 chip (even if the data got off, the encryption keys were lost with the T2 chip). The T2 also brought about the linkage of component serial numbers of certain internal components, such as the solid state storage, display, and trackpad, among other components. In fact, many other controllers on the logic board are now also paired to the T2, such as the WiFi and Bluetooth controller, the PMIC (Power Management Controller), and several other components. This is the exact same system used on newer iPhone models and is quite familiar to technicians who repair iPhone logic boards. While these changes are fantastic for device security and corporate and enterprise users, allowing for a very high degree of assurance that devices will refuse to boot if tampered with in any way - even from storied supply chain attacks, or other malfeasance that can be done with physical access to a machine - it has created difficulty with consumers who more often lack the expertise or awareness to keep critical data backed up, as well as the funds to perform the necessary repairs from authorized repair providers. Other issues reported that are suspected to be related to T2 are audio “cracking” or distortion on the internal speakers, and the BridgeOS becoming corrupt following a firmware update resulting in a machine that can’t boot.
I believe these hiccups will be properly addressed once macOS is fully integrated with the ARM platform. This stage of the Mac is more like a chimera of an iPhone and an Intel based computer. Technically, it does have all of the parts of an iPhone present within it, cellular radio aside, and I suspect this fusion is why these issues exist.
Recently, security researchers discovered an underlying security problem present within the Boot ROM code of the T1 and T2 chip. Due to being the same fundamental platform as e