Teardown of Apple's S1 Watch chip reveals custom CPU, 512MB RAM, 8GB flash storage, components from ADI and IDT
Early Looks Inside Apple Watch's S1 Chip Confirm 512 MB RAM, Unexpected Suppliers — Since the Apple Watch's initial unveiling last September, Apple has touted the S1 chip …
Context & Ripple Effects
iFixit already cracked open the case a week ago (revealing the 205mAh battery and Taptic Engine) — this teardown goes a layer deeper, confirming at die level that the S1 is not an off-the-shelf part but a package built around a custom CPU. It also settles the storage question raised by March's report that the watch carries 8 GB of flash with only 2 GB free for music and 75 MB for photos.
The surprise names are the suppliers: Analog Devices and IDT win visible slots inside Apple's most closely watched new hardware. Eight years on, the same silicon line runs from this first custom wearable CPU through the S8's reuse of the S6/S7 core to the Series 9's four-core neural engine — which is why the S1's architecture matters beyond 2015.
First-order effects
- ADI and IDT gain confirmed design wins inside the Apple Watch, giving both vendors a marquee reference in wearables just as the category takes off.
- App developers now know their real envelope: 512MB of RAM and roughly a quarter of the 8GB flash usable for media constrains what third-party watch apps can ship.
Second-order effects
- Rival smartwatch makers face pressure to match Apple's vertically integrated single-package approach rather than assembling commodity application processors, since the S1's density enables the watch's slim industrial design.
- Small analog and timing-component suppliers like ADI and IDT become acquisition targets or consolidation candidates as module integrators seek their sockets.
Third-order effects
- The S1 establishes the template for Apple's silicon strategy across categories: custom cores first, then specialized accelerators — a path the coverage traces directly to the S9's neural engine and on-device Siri, and one that widens the gap between Apple and rivals reliant on merchant chip vendors.
- If the S-series cadence holds — long stretches of reused CPUs punctuated by architectural jumps — wearable performance becomes a differentiator driven by Apple's internal roadmap rather than the broader mobile-chip market's.
The trend: Apple's wearable silicon is evolving from the S1's first custom-package proof toward a self-paced chip cadence where neural-engine capability, not raw clock speed, marks each generation.