Xenon (processor)

Xenon is a CPU that is used in the Xbox 360 game console. The processor, internally codenamed "Waternoose" by IBM [" [http://www.reed-electronics.com/CA6328378.html Learning from failure] - The inside story on how IBM out-foxed Intel with the Xbox 360", Dean Takahashi, "Electronic Business", May 1 2006] and "XCPU" by Microsoft, is based on IBM's PowerPC instruction set architecture, consisting of three independent cores on a single die. Each of the cores 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 processors are labelled "XCPU" on the packaging and are manufactured by Chartered. Chartered reduced the fabrication process in 2007 to 65 nm, thus reducing manufacturing costs for Microsoft.

The name "Xenon" was repurposed from the code name for the Xbox 360 in early development.

pecifications

*90 nm processcite web|url=http://www.ibm.com/developerworks/power/library/pa-fpfxbox/|title=Application-customized CPU design: The Microsoft Xbox 360 CPU story|accessdate=2007-09-08|author=Jeffrey Brown|date=2005-12-06] , 65 nm process upgrade in 2007cite web|url=http://news.teamxbox.com/xbox/10754/Chartered-to-Manufacture-65nm-Xbox-360-CPUs/|title=Chartered to Manufacture 65-nm Xbox 360 CPUs|accessdate=2008-01-09|author=César A. Berardini|date=2006-08-21] (codenamed "Falcon"), possible 45 nm process dated around 2008.cite web|url=http://www.pcadvisor.co.uk/news/index.cfm?newsid=10265|title=Improved Xbox 360 processor planned|accessdate=2008-01-09|author=Sumner Lemon|date=2007-08-01]
*165 million transistors
*Three symmetrical cores, each two way SMT-capable and clocked at 3.2 GHz
*SIMD: VMX128 with 2× (128×128 bit) register files for each core.
*1 MiB L2 cache (lockable by the GPU) running at half-speed (1.6 GHz) with a 256-bit bus
*51.2 gigabytes per second of L2 memory bandwidth (256 bit × 1600 MHz)
*21.6 GB/s Front-Side Bus
*Dot product performance: 9.6 billion per second
*115.2 GFLOPS theoretical peak performance
*Restricted to In-order code execution
*ROM storing Microsoft's Secure Bootloader
*Big endian architecture.

References

* [http://forums.xbox-scene.com/index.php?showtopic=231928 Xenon hardware overview] by Pete Isensee, Development Lead, Xbox Advanced Technology Group, written some time before 23 June 2004

External links

* [http://arstechnica.com/articles/paedia/cpu/xbox360-2.ars Ars Technica explains the Xenon CPU]