The codename of the Xbox 360’s three-core IBM PowerPC processor was Xenon.
Xenon was designed specifically for the Xbox 360 and contained three symmetric processing cores running at 3.2 GHz. Its architecture differed substantially from the single-core Intel Pentium III-based processor used by the original Xbox. The processor gave developers more parallel CPU capacity for game logic, physics, audio, and other tasks.
Xenon is often confused with Xenos, the codename for the Xbox 360’s ATI-designed graphics processor. They were separate chips with different jobs. The console also used a unified memory architecture, allowing developers to share its 512 MB of GDDR3 memory between CPU and graphics workloads.
IBM manufactured the processor, while Microsoft integrated it into the Xbox 360’s custom system design. The Xenon name is therefore a hardware codename, not the consumer-facing name of the console or its operating system.