Xenon (processor)

Waternoose processor (with remaining thermal paste)

Xenon is a CPU that is used in the Xbox 360 game console. The processor, internally codenamed "Waternoose" by IBM^[1] and "XCPU" by Microsoft is based on IBM's PowerPC technology, consisting of 3 independent cores on a single chip. 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.

Specifications

• 90 nm process, 65 nm process upgrade in 2007 (codenamed "Falcon"), 165 million transistors (possible 45 nm process dated around 2008)^[2]
• Three symmetrical cores, each two way SMT-capable and clocked at 3.2 GHz^[2]
• SIMD: VMX128 with 2× (128×128 bit) register files for each core.^[2]
• 1 MiB L2 cache^[2] (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^[2]
• Dot product performance: 9.6 billion per second
• 116 GFLOPS theoretical peak performance
• Restricted to In-order code execution^[2]
• ROM storing Microsoft's Secure Bootloader
• Big endian architecture.

References

1. ^ "Learning from failure - The inside story on how IBM out-foxed Intel with the Xbox 360", Dean Takahashi, Electronic Business, May 1 2006
2. ^ ^{a b c d e f} Jeffrey Brown (2005-12-06). Application-customized CPU design: The Microsoft Xbox 360 CPU story. Retrieved on 2007-09-08.

• Xenon hardware overview by Pete Isensee, Development Lead, Xbox Advanced Technology Group, written some time before 23 June 2004

External links

• Ars Technica explains the Xenon CPU