When Apple launched its new 2016 MacBook Pro models last week, all attention was clearly on the Touch Bar, a new multi-touch controller surface which changes dynamically to offer context-relevant tools, and can be interacted with in a variety of ways. As more details of how it works emerge, TechCrunch has confirmed that it takes advantage of hardware and software derived from the Apple Watch, including a custom ARM-based processor and watchOS itself.
TechCrunch cites tweets by developer Steve Troughton-Smith as well as additional research that back up his findings. Apple announced that Touch ID on its new MacBook Pros is implemented using the same Secure Enclave architecture that it uses on iPhones, but now integrated into a new custom T1 processor, derived from the S2 which powers current Apple Watch models.
The primary OS and CPU are never involved when accessing secure data, such as when authenticating an Apple Pay transaction with a fingerprint - in the case of the iPhone, that means one of Apple's own A-series SoCs and iOS, whereas now Intel x86 CPUs and macOS can also be bridged. Fingerprint patterns are stored only within the Secure Enclave, and it is paired to the parent device with a unique identifier at the time of manufacture, which means separating the two will cause Touch ID to stop working - and also means that replacing parts might result in a loss of functionality.
The Touch Bar essentially runs its own embedded OS, which is derived from watchOS. The main computer generates graphics for it and reacts to its touch inputs, which are sent and received over USB just as any input/output peripheral would. Troughton-Smith theorises that the Touch Bar could therefore work as an independent device even when the MacBook Pro is turned off.
Apple has long been rumoured to be working on more powerful versions of its iOS devices' A-series chips to replace the Intel processors in some if not all of the Mac lineup. Apple has also famously resisted using touchscreens on its desktops and laptops, clearly delineating its Mac and iOS philosophies. This approach shows that Apple has brought the two together in ways that serve specific purposes.
Touch Bar debuted with the new MacBook Pro 2016. It is not currently available on any other models, but if Apple wants to establish common conventions across its product lines and keep developers motivated to support it, a standalone keyboard for at least the Mac Pro should launch soon. However, the feature has pushed the price of the MacBook Pro 2016 up considerably, compared to the non-Touch Bar model as well as the previous generation, which was introduced in 2012.