|Used In||Original Xbox 360|
|Instruction Set||PowerPC RISC|
The Microsoft XCPU, codename Xenon, is the central processor used in the Xbox 360. It is designed to be used with the ATi Xenos graphics chip, which also functions as the northbridge and memory controller.
Waternoose is the first "real" CPU for the Xbox 360, replacing the earlier Shiva CPU, which was only used for early development.
- 3 two-way SMD-capable RISC cores clocked at 3.2GHz
- SIMD: Two VMX128 units
- 32KB L1 data cache
- 32KB L1 instruction cache
- 1MB L2 cache at 1.6 GHz with a 256-bit bus
- 21.6GB/s FSB
- 768 bits of IBM eFUSE one-time-program memory
- ROM and 64KB SRAM for storing the 1BL
- Big-endian architecture
All version of the XCPU contain a One-Time-Programmable (OTP) Secure ROM using eFUSEs. This ensures that it can never be modified after being written. The Secure ROM contains the 1BL, config ring, and configuration fuses.
In 2007, the XCPU was shrunk and slightly redesigned for the 65nm process. Known as Loki, it is used on the Falcon and Jasper motherboards. It is notable for having significantly lower power and thermal requirements.