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apple’s T1: a chip with room to grow


...ARM-based IC in MacBook Pro running TouchBar & TouchID ... at least CPU, GPU, Image Signal Processor & Secure Enclave (dedicated block & memory) ... wider use likely planned ... what are other applications of T1's functionality?

It is now two weeks since Apple’s MacBook Pro event.  In this time pundits have been almost universally critical of Apple’s choice not to make the MacBook Pro’s display a touch screen.  Microsoft held its own event two days before Apple.  At their event the Surface Studio Pro, an all-in-one touch screen desktop, was introduced.  The press was quick to pass the innovation crown from Apple to Microsoft.  I am not going to wade into this debate here other than to say that Asymco published a reasoned take on Apple’s decision.  Touch screen or no touch screen the Apple Event brought us another, new Apple IC; the T1.  The media seems to have largely overlooked the T1, but this IC might just be part of the groundwork for things to come. It is time to think about it.

what we were told?

In a nutshell; we were not told much.  The discussion around the Touch Bar gets under way at around 36:30 of the October 2016 Apple Event.  Then at 38:00 we hear more detail about Touch ID, including that one can log-in with their fingerprint.  This is where we are introduced to the T1 and the “Secure Enclave” with the slide reproduced below.  That is all we were told.

apple-t1_screen

Source: Apple

what we have learned since?

Articles appeared in arstechnia and AppleInsider within a day of the Apple Event.  A number of interesting details came out of the arstechnia piece.  They indicated the touch bar is 2170×60 (130200) pixels.  There is an ARMv7 CPU, an Image Signal Processor that is similar to that in the A-series SoC’s.  Graphics data is said to move from the primary GPU to the T1, which provides images  to the Touch Bar.  Then there is the “Secure Enclave” as Apple coined it.  It is said to encrypt and store fingerprint data.  At this point one is taken back to the A7 and the introduction of Touch ID in the iPhone.  At least initially, it was hypothesized that fingerprint data was stored in two blocks of SRAM on the A7.  Finally, it was said that the T1 runs a version of the watchOS.

AppleInsider pegged the Touch Bar at 2180×80 (174400) pixels.  It was indicated that the T1 runs a version of iOS. There was additional discussion around the use of TouchID and the T1 in the start-up/ log-in process and how the Touch Bar might be repaired.

where can we go with these details?

I guess the first place to go is the die.  As noted by Apple the T1 is an SoC.  In terms of cores, there will be a CPU, an Image Signal Processor and maybe a GPU.  The nature of the graphics-based cores will be a function of how the T1 handles the graphic information provided from the main GPU, and what image manipulation occurs.  What about memory? Will we see a block or blocks of SRAM for fingerprint storage, or will a separate memory die be in the package?  The encryption portion of the Secure Enclave’s functionality may well be a separate core.  In general one anticipates some of the cores will be similar to those of the A-series dies.  Those associated with Touch ID are a good example.  It is the same functionality, the same processing and the same amount of data as is required in the A-series die, so it should be the same core.

The T1 SOC provides two functionalities.  First, it receives graphic’s information from the main GPU and manipulates it for display.  Scrolling through photos on the Touch Bar is a good example.  Raw images might come to the T1 from the main GPU as a stream.  The T1 then creates the scrolling images, where the one of interest is shown as a whole, albeit smaller, image while the others are rendered as slender rectangles.  Second, it provides the compute functionality for Touch ID.  The T1 acts as a sort of “bridge” between the Intel macOS environment and the Touch ID ARM-based systems that were developed for the A-series processors.

Now it is time for the fun part.  It is time to put on our thinking caps.  It seems natural that one would bring the same Touch Bar and Touch ID functionality to other Macs.  For the desktops this could be via the keyboard.  I am not the first to say this, but the integration of a Touch Bar/ ID might be brought to external keyboards with any refresh of the desktops.

There is one other use that jumps out.  The smallest estimate for the Touch Bar display i.e. 130200 pixels is larger than the largest AppleWatch display at 121690 pixels.  Could one put a  display, Touch ID and the T1 into the Apple TV remote?  In this scenario one could have secondary program information in the form of thumbnail images or scrolling within a replica of the TV image in the remote.  The touch ID would allow for secure purchases.  It might also allow a preset selection of channels become available depending on who is holding the remote.  The family could have customized TV feeds or movie suggestions through Touch ID.

In the end, the T1 should be an interesting die that draws from the A-series processor work.  There are some intriguing use scenarios falling out of its capabilities.  Apple TV is one.  IoT devices that might be in the pipe are another.  From a broader perspective Apple is continually pushing its semiconductor design efforts, yielding an expanding portfolio of ICs, which are expanding the capabilities of Apple products.  Don’t pass the crown just yet.