Microsoft XCPU, codenamed Xenon, is a CPU used in the Xbox 360 game console, to be used with ATI's Xenos graphics chip.
The processor was developed by Microsoft and IBM under the IBM chip program codenamed "Waternoose", which was named after Henry J. Waternoose III in Monsters, Inc.. The development program was originally announced on 2003-11-03.
The processor is based on IBM PowerPCinstruction set architecture. It consists of three independent processor cores on a single die. These cores are slightly modified versions of the PPE in the Cell processor used on the PlayStation 3. Each core has two symmetric hardware threads (SMT), for a total of six hardware threads available to games. Each individual core also includes 32 KiB of L1 instruction cache and 32 KiB of L1 data cache.