Apple Watch runs 'most' of iOS 8.2, may use A5-equivalent processor
The Apple Watch is using "most" of iOS 8.2, with a new subsystem called "Carousel" in place of the Springboard homescreen found on iPhones and iPads, developer Steve Troughton-Smith said on Thursday, also suggesting that the Watch's S1 processor appears to be equivalent to the Apple A5.

Posting on Twitter, Troughton-Smith noted that the Watch firmware contains a PowerVR SGX543 driver. The SGX543 is the same graphics component found in the A5, which Apple first shipped with the iPad 2 and iPhone 4S back in 2011.
The S1 though is a much more compressed chip design, building everything the device needs into a system-in-package surrounded by resin for extra protection. Apple has said relatively little about the technology beyond that, making it difficult to gauge performance.
The Watch firmware is not officially considered a version of iOS. Since it has to interact with a paired iPhone, however, it makes sense for it to be founded in the same general codebase.
Troughton-Smith further observed that all of the Watch Faces are stored in a single framework, called NanoTimeKit. Those Faces use SpriteKit graphics, but animated faces like Mickey Mouse apply OpenGL for rendering.

Posting on Twitter, Troughton-Smith noted that the Watch firmware contains a PowerVR SGX543 driver. The SGX543 is the same graphics component found in the A5, which Apple first shipped with the iPad 2 and iPhone 4S back in 2011.
The S1 though is a much more compressed chip design, building everything the device needs into a system-in-package surrounded by resin for extra protection. Apple has said relatively little about the technology beyond that, making it difficult to gauge performance.
The Watch firmware is not officially considered a version of iOS. Since it has to interact with a paired iPhone, however, it makes sense for it to be founded in the same general codebase.
Troughton-Smith further observed that all of the Watch Faces are stored in a single framework, called NanoTimeKit. Those Faces use SpriteKit graphics, but animated faces like Mickey Mouse apply OpenGL for rendering.
Comments
imagine the performance of iPhone 5S inside this little puppy...very impressive.
Ugh, the A5 has lived way too long.
4S is still used by many out there. What's wrong? It's a damn watch and doesn't need all the power of the latest chip. You like to put 4.0L V-8 engine in a Fiat500?
On the watch backwards compatible 32-bit instructions wouldn't be required, so all that could be left off the chip.
It's a stretch to assume a specific CPU core just because of the presence of a certain GPU.
Might have been meaningful to put a 64-bit ARM in there without 32-bit backwards compatible instruction set, since as I remember from the A7 introduction, it was said the 64-bit instruction set was designed to use less power, and that 64-bit apps use less power.
On the watch backwards compatible 32-bit instructions wouldn't be required, so all that could be left off the chip.
It's a stretch to assume a specific CPU core just because of the presence of a certain GPU.
It's very possible that they're using PowerVR SGX543 but a 64-bit single core cpu from the 5S, just like they used a single core of the A5 chip on the Apple TV. Plus Apple is requiring developers to submit 64-bit only applications. Older devices will get the 32-bit variant of the same app since they're archived.
We'll probably learn more as more people get their hands on the Apple Watch.
The A5 is a technological dinosaur that needs to be killed off ASAP (same with the A6). A7 and newer are being held back by those deadweights. iOS will benefit greatly from being able to dump almost all the 32-bit portions, and we'll get apps that are 64-bit only.
Yeah ...
Someone will Jailbreak the Apple Watch and then install Apache ...
An Apple Watch as a Web Server ... Told you the iPhone is an accessory to the Apple Watch
I agree with some on here... The GPU used is not a good way to determine what CPU is being used. Apple is obviously going to use a less capable GPU because the screen is fairly small and animations aren't running amok - all the extra benefits of having a powerful GPU just don't make sense on a device of this type. Efficiency is most important, so I also tend to believe that they are using a new 64 bit CPU core, possibly even stripped of 32 bit-ness which is no longer needed, especially on a brand new device/platform.
We'll know more after WWDC when Apple is supposed to reveal WatchKit 2.0 which is supposed to enable full blown apps on the watch.
But the Apple Watch isn't doing any heavy processing -- it's just an intermediary with the phone doing all the heavy lifting. Doesn't make sense to use a modern 64-bit processor for a glorified "second" screen for your iPhone.
Why do you say that in the context of the Watch?
It is possible that Apple would over-spec and under clock the CPU to allow the S1 package to last for more than 1 generation of watch.
I think we'll learn a lot when we get some teardown info.
Can we talk about Macs yet? What's this, 10,000 consecutive articles about the AWatch?
It is possible that Apple would over-spec and under clock the CPU to allow the S1 package to last for more than 1 generation of watch.
I think we'll learn a lot when we get some teardown info.
Possible also that Apple might under clock the processor to reduce current consumption.
Bring on the teardowns! Bring on the chip-decapsulations! Bring on the third party analysis!
Without the interface fanciness, an A5 should be able to drive the Apple Watch display with no issue.
In a year and a half, this watch will have twice the processing power at the same price. Incredible.
The 64 bit Arm instruction set is designed to be very power efficient. By stripping out all 32 bit support they would reduce power usage even further. By the way I'm not saying it is 64 bit as I'm not sure Apple has the balls to look that far into the future, just that bitness is not a serous issue either way.
Not that I really care as I don't see a watch in my future. The point is there is an argument for a 64 bit chip that can't be dismissed.
More important to me is what size process does it use? 28nm? 20nm? If they can get the S2 onto the new 14nm or 16nm processes from Samsung or TSMC, then they can likely squeeze more battery life out of the next version.