Xenon (processor)

Xenon was the codename for the central processing unit (CPU) used in the Microsoft Xbox 360 video game console. It was jointly developed by IBM and Microsoft, and is based on the PowerPC architecture.

Overview

The Xenon processor is a tri-core processor, meaning it contains three independent processing cores within a single physical chip. Each core is capable of simultaneously executing two threads, enabling the processor to handle six threads in total. This design was chosen to provide increased processing power and improve the overall gaming experience on the Xbox 360.

Architecture

Xenon uses a customized version of the PowerPC 970 architecture. Key architectural features include:

• Tri-Core Design: As mentioned above, it utilizes three independent cores.
• Simultaneous Multithreading (SMT): Each core supports two hardware threads.
• Vector Math Unit (VMX-128): This SIMD (Single Instruction, Multiple Data) unit, similar to AltiVec, accelerates vector-based calculations common in graphics and physics processing.
• Front-Side Bus (FSB): Xenon connects to the system's Northbridge chip via a dedicated FSB.
• Embedded DRAM (eDRAM): The processor package includes a substantial amount of eDRAM, which serves as a high-bandwidth, low-latency memory cache, improving memory performance for graphics rendering.

Technical Specifications (Typical)

• Clock Speed: 3.2 GHz per core
• Number of Cores: 3
• Threads: 6
• L1 Cache: 32 KB Instruction Cache, 32 KB Data Cache per core
• L2 Cache: 1 MB unified cache shared by all three cores
• Manufacturing Process: 90 nm initially, later transitioned to 65 nm and 45 nm to improve power efficiency and reduce heat.
• Power Consumption: Varied depending on manufacturing process and usage.

Significance

The Xenon processor was a significant component of the Xbox 360's hardware. Its tri-core design and support for simultaneous multithreading were innovative at the time and contributed to the console's processing capabilities, enabling more complex and visually rich games. The collaboration between IBM and Microsoft in designing Xenon was also noteworthy, representing a significant investment in custom hardware for the gaming market. The processor's architectural choices and performance characteristics had a direct impact on the types of games that could be developed and played on the Xbox 360 platform.