Xenon (processor)

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Not to be confused with the ATI Xenos (also used in the Xbox 360 as the GPU), or the unrelated Intel Xeon.
Microsoft XCPU (codenamed Xenon)
KL Microsoft XBOX 380 CPU ES.jpg
Picture of the microprocessor (XCPU-ES shown).
Designed by IBM
Common manufacturer(s)
Instruction set Power Architecture
Cores 3 (physical), 6 (logical)
L1 cache 32/32 kB
L2 cache 1024 kB

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..[1] The development program was originally announced on 2003-11-03.[2]

The processor is based on IBM PowerPC instruction 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.[3][4] 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.

The XCPU processors are manufactured at IBM's East Fishkill, New York fabrication plant and Chartered Semiconductor Manufacturing (now part of GlobalFoundries) in Singapore.[5] Chartered reduced the fabrication process in 2007 to 65 nm from 90 nm, thus reducing manufacturing costs for Microsoft.



The Xbox 360 S introduced the XCGPU, which integrated the Xenon CPU and the Xenos GPU onto the same die, and the eDRAM into the same package. The XCGPU follows the trend started with the integrated EE+GS in PlayStation 2 Slimline, combining CPU, GPU, memory controllers and IO in a single cost-reduced chip. It also contains a "front side bus replacement block" that connects the CPU and GPU internally in exactly the same manner as the front side bus would have done when the CPU and GPU were separate chips, so that the XCGPU doesn't change the hardware characteristics of the Xbox 360.

XCGPU contains 372 million transistors and is manufactured by GlobalFoundries on a 45 nm process. Compared to the original chipset in the Xbox 360 the combined power requirements are reduced by 60% and the physical chip area by 50%.[10][11]


Illustrations of the different generations of processors in Xbox 360 and Xbox 360 S.


  • Xenon hardware overview by Pete Isensee, Development Lead, Xbox Advanced Technology Group, written some time before 23 June 2007

External links[edit]