As our "ATI Xenos: XBOX 360 Graphics Demystified" article investigates, the graphics processor for the XBOX 360 console is split into two elements, the main parent "shader core" (manufactured by TSMC at 90nm) which handles most of the graphics operations and the ALU arrays for processing shader programs and a secondary, daughter die (manufactured by NEC at 90nm) which handles the all the sample operations (colour read/blend/write, Multi-Sample AA, Z operations, etc.) and a fast dedicated 10MB of eDRAM that acts as the processors primary frame buffer, that has 256GB/s of bandwidth available to it. We've been supplied with an image of the chip package for the Xenos graphics processor:
The parent/daughter die is quite clearly evident on the same package from this image. While the 232M transistor figure for the parent was given to us by ATI we are still trying to establish a more official figure for the daughter (even though these things are very much estimates). We've speculated that the 150M figure that appeared when XBOX 360 was first announced may just relate to daughter die, however another figure that has arisen is 100M - judging from the die sizes the daughter die doesnt have more than half the area of the parent, which would give indications towards the 100M side although 80M of those transistors are DRAM which may be more dense than the logic circuitry that will dominate the parent die. We are trying to get further clarification.
