Mark Gurman and Ian King in a February 2017 report for Bloomberg:
Apple Inc. is designing a new chip for future Mac laptops that would take on more of the functionality currently handled by Intel Corp. processors, according to people familiar with the matter.
The chip, which went into development last year, is similar to one already used in the latest MacBook Pro to power the keyboard’s Touch Bar feature, the people said. The updated part, internally codenamed T310, would handle some of the computer’s low-power mode functionality, they said. The people asked not to be identified talking about private product development. It’s built using ARM Holdings Plc. technology and will work alongside an Intel processor.
The current ARM-based chip for Macs is independent from the computer’s other components, focusing on the Touch Bar’s functionality itself. The new version in development would go further by connecting to other parts of a Mac’s system, including storage and wireless components, in order to take on the additional responsibilities. Given that a low-power mode already exists, Apple may choose to not highlight the advancement, much like it has not marketed the significance of its current Mac chip, one of the people said.
It sounds like this is the chip that is included in the iMac Pro, even though Gurman and King cite lower power tasks as being the focus of its development. Steven Troughton-Smith in November:
This looks like the iMac Pro’s coprocessor (Bridge2,1) will be an A10 Fusion chip with 512MB RAM […] So first Mac with an A-series chip
Rene Ritchie tweeted today that the A10 has been rebranded “T2” — as in, a successor to the T1 chip in Touch Bar MacBook Pro models.
Cabel Sasser of Panic received an iMac Pro review unit from Apple, and tweeted about the T2’s functionality:
It integrates previously discrete components, like the SMC, ISP for the camera, audio control, SSD control… plus a secure enclave, and a hardware encryption engine.
This new chip means storage encryption keys pass from the secure enclave to the hardware encryption engine in-chip — your key never leaves the chip. And, they it allows for hardware verification of OS, kernel, boot loader, firmware, etc. (This can be disabled…)
In addition to the enhanced security measures Sasser notes, a couple more things are very exciting about Apple’s gradual rollout of a proprietary coprocessor in their Mac lineup. The T2 sounds like it expands upon some of the input mechanism security measures of the T1, so the keyboard and built-in camera are more secure than previous implementations. And, as Guilherme Rambo noticed, it can enable “Hey, Siri” functionality on the Mac. But Apple hasn’t enabled that functionality; so, now, it is a question of “when?”.