Just a few hours after the iPhone 5S was released, Chipworks has reverse-engineered the A7 SoC, and located the elusive M7 sensor-oriented coprocessor. While the reverse-engineering is ongoing, Chipworks has already ascertained that the A7 is made by Samsung, not TSMC, despite the ongoing legal battles between the two companies. It also turns out that, despite the significant time spent discussing and extolling the virtues of the M7 coprocessor, it’s really just a tiny, standard Cortex-M3 core.

By taking apart an iPhone 5S, and then removing the top of the A7 SoC, Chipworks was able to ascertain that the chip was made using Samsung’s 28nm high-k metal gate technology. It had been rumored that the SoC would be produced by TSMC instead of Samsung, but it would seem that isn’t the case. It would take a lot of work to move from Samsung to TSMC, and perhaps Apple just isn’t ready to make hte jump. The move to 28nm bought Apple ~12.5% die space savings compared to 32nm, with modest power saving. (See: How to crack open some computer chips and take your own die shots.)

According to a new teardown posted by Chipworks, the M7 sensor-oriented coprocessor that Apple’s talked up as an always-on enhancement for the iPhone 5S is, in fact, a Cortex-M3 core built by NXP, the NXP LPC18A1. This part doesn’t have an exact public SKU, but looking at NXP’s product line, we can get a feel for what the chip’s specs are likely to be. The chip has a three-stage pipeline, likely runs at 180MHz (though lower clock speeds are possible), and can contain up to 1MB of NAND memory. The chip also has 136KB of on-board SRAM for program storage.

This is an ultra-lightweight processor designed for embedded microcontroller systems, so Apple’s use of the Cortex-M3 (as the M7) makes sense. That should also make it easier for developers to target the chip — it uses a standard well-known set of instructions and capabilities and it’s dedicated to processing input from the gyroscope, accelerometer, and electromagnetic compass aboard the platform.

Taken as a whole, the 5S’s design is evolutionary. While the A7 processor is much faster than its predecessor, other components, like the WiFi modem (Broadcomm BCM4334) or Qualcomm LTE modem and transceivers are all substantially identical to the products that shipped with the iPhone 5. Given the long rollout time for standards like 802.11ac or next-generation LTE devices, neither of these are must-haves.

As an aside, it’s amazing to see just how small the logic board hat drives these products truly is. The PCB you’re looking at accounts for only part of the total volume within the device, but contains most of the essential circuitry (apart from the screen digitizer, battery, and buttons) that make the phone work. Chipworks’ website is currently down under heavy load, but the full article and conclusions from their teardown will hopefully be available later.

Now Read: iPhone 5S teardown: Touch ID sensor, A7 SoC, but M7 coprocessor mysteriously missing