Les rumeurs concernant les spécifications de la prochaine console de
Microsoft (qui a pour nom de code
Xenon) vont bon train, après des rumeurs disant que cette console ne serait pas compatible avec la
Xbox et la réponse de
Microsoft. Voici que
SPOnG dit avoir mis la main sur un
mémo interne de la société de Redmond décrivant les capacités de la console.
Xenon is powered by a 3.5+ GHz IBM PowerPC processor and a 500+ MHz ATI graphics processor. Xenon has 256+ MB of unified memory. Xenon runs a custom operating system based on MS Windows NT, similar to the Xbox operating system. The graphics interface is a superset of MS Direct3D version 9.0.
La
Xenon est équipée d'un processeur PowerPC à 3,5 GHz et d'un VPU ATI cadencé à 500 MHz, elle a 256 Mo de mémoire unifiée. L'API sera un dérivé de Direct3D 9.0.
The Xenon CPU is a custom processor based on PowerPC technology. The CPU includes three independent processors (cores) on a single die. Each core runs at 3.5+ GHz. The Xenon CPU can issue two instructions per clock cycle per core. At peak performance, Xenon can issue 21 billion instructions per second.
The Xenon CPU was designed by IBM in close consultation with the Xbox team, leading to a number of revolutionary additions, including a dot product instruction for extremely fast vector math and custom security features built directly into the silicon to prevent piracy and hacking.
Each core has two symmetric hardware threads (SMT), for a total of six hardware threads available to games. Not only does the Xenon CPU include the standard set of PowerPC integer and floating-point registers (one set per hardware thread), the Xenon CPU also includes 128 vector (VMX) registers per hardware thread. This astounding number of registers can drastically improve the speed of common mathematical operations.
Each of the three cores includes a 32-KB L1 instruction cache and a 32-KB L1 data cache. The three cores share a 1-MB L2 cache. The L2 cache can be locked down in segments to improve performance. The L2 cache also has the very unusual feature of being directly readable from the GPU, which allows the GPU to consume geometry and texture data from L2 and main memory simultaneously.
Xenon CPU instructions are exposed to games through compiler intrinsics, allowing developers to access the power of the chip using C language notation.
The Xenon GPU is a custom 500+ MHz graphics processor from ATI. The shader core has 48 Arithmetic Logic Units (ALUs) that can execute 64 simultaneous threads on groups of 64 vertices or pixels. ALUs are automatically and dynamically assigned to either pixel or vertex processing depending on load. The ALUs can each perform one vector and one scalar operation per clock cycle, for a total of 96 shader operations per clock cycle. Texture loads can be done in parallel to ALU operations. At peak performance, the GPU can issue 48 billion shader operations per second.
The GPU has a peak pixel fill rate of 4+ gigapixels/sec (16 gigasamples/sec with 4× antialiasing). The peak vertex rate is 500+ million vertices/sec. The peak triangle rate is 500+ million triangles/sec. The interesting point about all of these values is that they’re not just theoretical—they are attainable with nontrivial shaders.
Xenon is designed for high-definition output. Included directly on the GPU die is 10+ MB of fast embedded dynamic RAM (EDRAM). A 720p frame buffer fits very nicely here. Larger frame buffers are also possible because of hardware-accelerated partitioning and predicated rendering that has little cost other than additional vertex processing. Along with the extremely fast EDRAM, the GPU also includes hardware instructions for alpha blending, z-test, and antialiasing.
The Xenon graphics architecture is a unique design that implements a superset of Direct3D version 9.0. It includes a number of important extensions, including additional compressed texture formats and a flexible tessellation engine. Xenon not only supports high-level shading language (HLSL) model 3.0 for vertex and pixel shaders but also includes advanced shader features well beyond model 3.0. For instance, shaders use 32-bit IEEE floating-point math throughout. Vertex shaders can fetch from textures, and pixel shaders can fetch from vertex streams. Xenon shaders also have the unique ability to directly access main memory, allowing techniques that have never before been possible.
As with Xbox, Xenon will support precompiled push buffers (“command buffers” in Xenon terminology), but to a much greater extent than the Xbox console does. The Xbox team is exposing and documenting the command buffer format so that games are able to harness the GPU much more effectively.
In addition to an extremely powerful GPU, Xenon also includes a very high-quality resize filter. This filter allows consumers to choose whatever output mode they desire. Xenon automatically scales the game’s output buffer to the consumer-chosen resolution.
Et pour finir :
People often ask if Xenon can be backward compatible with Xbox. Although the architecture of the two consoles is quite different, Xenon has the processing power to emulate Xbox. Whether Xenon will be backward compatible involves a variety of factors, not the least of which is the massive development and testing effort required to allow Xbox games run on Xenon.
Ceci raconte que même si l'architecture des deux consoles est très différente, la
Xenon a assez de puissance pour émuler la
Xbox, mais cela demanderait beaucoup de développement et de tests.
