We’ve already seen the Apple Watch get torn apart by iFixit, giving us an inside look at the Taptic Engine, Digital Crown, and (mostly) battery, and now ABI Research has gone a level further and opened up the custom designed S1 chip that is the brains of the Apple Watch…

As part of its Teardowns Market Research effort, ABI illustrates each component packed into the tiny, weather resistant module including WiFi, Bluetooth, and NFC radios.

The photo also reveals 512 MB of RAM sourced from Elpida, 8GB of flash storage sourced from SanDisk/Toshiba, and the integrated accelerometer/gyroscope sensor. The real brains of the S1 chip can be found in a customer Apple processor labeled APL 0778. As you can see, the S1’s main processor makes up a fraction of the already ultra compact system.

Apple describes the Watch’s S1 chip as “an entire computer system on a single chip” that it encapsulates in resin to add to its durability and withstand the elements. This contributes to the Apple Watch’s IPX7 water-resistance rating, which we saw tested on launch day with 15 minutes of water submersion not impacting the performance. For scale, the S1’s main processor makes up a fraction of the already ultra compact system.

Tiny ARM processor:

Yes, that’s a golf ball and 20 pin ARM Cortex M0, 1.6×2.0mm, $0.75

No chance of hand soldering. pic.twitter.com/bAQdaI4LYX

— Joe Walnes (@joewalnes) April 30, 2015