RAM
The RAM used in the Xbox 360 is a single pool of 512MB GDDR3. The chips are clocked at 700MHz and sourced from various vendors.
Vendors
Architecture
The 512MB of RAM is shared between the CPU and GPU, with the GPU being the memory controller. Almost all of the RAM is accessible to games as the Xbox System Software is designed to have a very small memory footprint.
GPU Support
Xenos supports multiple RAM configurations from 128MB to 1GB.
| Name | Size | Qty | Chip Size |
|---|---|---|---|
| Xenos_128_4 | 128MB | 4 | 32MB |
| Xenos_256_4 | 256MB | 4 | 64MB |
| Xenos_256_8 | 256MB | 8 | 32MB |
| Xenos_512_4 | 512MB | 4 | 128MB |
| Xenos_512_8 | 512MB | 8 | 64MB |
| Xenos_1024_8 | 1GB | 8 | 128MB |
PCB Support
XDK-GB
Standard systems configured as a development kit had the normal amount of 512MB. In 2010, the XDK-GB was released with 1GB of RAM. Previous motherboards did not support 1GB due to the 13th addressing line to each chip being not connected. This was added along with other minor changes for the XDK-GB. This change was never made on motherboards that were not destined to have 1GB of RAM installed.
The RAM operates as 2 separate pools. The first 512MB is used the same way as a normal system, and the upper 512MB was used for debugging.This ensured that debugging tools did not take up memory that could otherwise be used by a game. The XDK-S based on the Xbox 360 S continued using 1GB RAM.