Technology glossary

Apple S9 SiP

The system in package introduced with Apple Watch Series 9 and Ultra 2, combining the processor, Neural Engine and Ultra Wideband chip in one package.

A SiP (system in package) combines the processor, memory and supporting chips in a single module. According to Apple’s tech specs, S9 has a 64-bit dual-core processor and a 4-core Neural Engine.

Apple says the Neural Engine runs machine learning tasks up to twice as fast as Series 8. This enables on-device processing of Siri requests that need no internet data, and the double tap gesture.

S9 includes a second-generation Ultra Wideband chip that provides distance and direction in Precision Finding with the iPhone 15 family. Ultra Wideband availability varies by region.

Devices using this technology

Smartwatches · 2023

Apple Watch Series 9 (45 mm, GPS, aluminium)

Apple Watch Series 9 is the generation that brought the double tap gesture, on-device Siri requests and a 2000-nit display with the S9 SiP. It offers electrical and optical heart sensors, temperature sensing, 50 m water resistance and 18-hour battery life. On some watches sold in the US the Blood Oxygen feature was unavailable for a period; it returned in August 2025 with a redesigned version that calculates the reading on iPhone. In independent testing heart rate came close to a chest strap and the display measured 1619 nits. Owners praise the brightness and double tap; battery life is described as one to two days depending on use.

Sources

  1. Apple Newsroom: Apple introduces Apple Watch Series 9 (12 September 2023)
  2. Apple Support: Apple Watch Series 9 tech specs