I have received some details from Terren about the architecture of the Xbox 360, and more specifically, its graphics subsystem.

Firstly, while the GPU and its 10 MB of embedded DRAM are manufactured seperately, they are present on the same physical package. The embedded DRAM clocks in at 2 GHz, and provides 256 GB/s of bandwidth. It is being dubbed "intelligent memory", for it contains 192 parallel pixel processors, allowing the memory to do independant processing of its own, and not compromising the performance of the GPU. Some of this processing includes 4x anti-aliasing at 720p, dynamic shadows, stencil buffer shadows, and occlusion culling.

Since the majority of heat produced is by the GPU/memory I/O, embedded DRAM allows the GPU to be cooled by a passive heatsink, along with the system fans already present in the Xbox 360. The "regular" 512 MB of GDDR3 system/graphics memory operates at 700 MHz.

Microsoft says that through the use of the XNA tools, it takes approximately one week to port PC applications to the Xbox 360, which ought to be a boon to developers.

Here are some pictures of the ATI/Microsoft press conference slides:<
http://img.neoseeker.com/v_image.php?ty ... 45&image=1
http://img.neoseeker.com/v_image.php?ty ... 45&image=2
http://img.neoseeker.com/v_image.php?ty ... 45&image=3
http://img.neoseeker.com/v_image.php?ty ... 45&image=4

Bien pour la Révolution sa devrait ressembler aux GPU de la Xbox 360 vu que c'est la même compagnie qui va le contruire (ATI). j'ai bien hâte de voir ces consoles en action

Vous pensez que le GPU de la Revolution pourrait être plus puissant que celui de le 360 ?

Pour la PS3 et son GPU, RSX reality synthesizer, c'est 2 fois la puissance d'une GeForce 6800 Ultra .C'est 100 billion shader operations comporé a 51 billion dot products per second pour un GPU GeForce6800. Wink

Bandwidth
The PS3 has 22.4 GB/s of GDDR3 bandwidth and 25.6 GB/s of RDRAM bandwidth for a total system bandwidth of 48 GB/s.

The Xbox 360 has 22.4 GB/s of GDDR3 bandwidth and a 256 GB/s of EDRAM bandwidth for a total of 278.4 GB/s total system bandwidth.


Why does the Xbox 360 have such an extreme amount of bandwidth? Even the simplest calculations show that a large amount of bandwidth is consumed by the frame buffer. For example, with simple color rendering and Z testing at 550 MHz the frame buffer alone requires 52.8 GB/s at 8 pixels per clock. The PS3's memory bandwidth is insufficient to maintain its GPU's peak rendering speed, even without texture and vertex fetches.

The PS3 uses Z and color compression to try to compensate for the lack of memory bandwidth. The problem with Z and color compression is that the compression breaks down quickly when rendering complex next-generation 3D scenes.

HDR, alpha-blending, and anti-aliasing require even more memory bandwidth. This is why Xbox 360 has 256 GB/s bandwidth reserved just for the frame buffer. This allows the Xbox 360 GPU to do Z testing, HDR, and alpha blended color rendering with 4X MSAA at full rate and still have the entire main bus bandwidth of 22.4 GB/s left over for textures and vertices.

Peut etre que c'est des gros chiffre, mais la bande passante n'est pas assez large pour en profiter. Cette analyse le confirme et probablement plusieurs autres.



http://xbox360.ign.com/articles/617/617951p3.html