The Xbox One was the first Microsoft console to use a custom AMD Jaguar CPU. Its system-on-chip combined eight low-power Jaguar CPU cores with AMD graphics technology and was developed for Microsoft's eighth-generation console.
AMD Jaguar was an x86-64 processor architecture designed for relatively efficient systems, and the Xbox One used a customized version rather than a standard desktop chip. This architecture helped the console run a broad operating-system environment alongside games, media functions, and background services.
The Xbox 360 used a custom IBM PowerPC-based Xenon processor, so it did not use Jaguar. The Xbox One X used a faster customized AMD design built on the same broad console generation, while Xbox Series systems moved to custom AMD Zen 2 CPUs. The question therefore refers specifically to the first Xbox hardware generation using Jaguar.