The memory specs of Microsoft's Xbox 720 (Next)

Posted by Trent Nouveau

Microsoft's Xbox 720 (Next) console is slated to make its long-awaited debut at E3 2013 in Los Angeles this June.

Although Redmond has yet to offer an official list of specs, a number of sites claim to have obtained detailed hardware information about the next-gen system.

One such site is the well-known VGLeaks, which recently posted a comprehensive schematic of the 720's memory system, and how it interacts with both the CPU and GPU.

Essentially, the central elements of the Durango memory system are the north bridge and the GPU memory system. According to VGLeaks, the memory system supports multiple clients (for example, the CPU and the GPU), coherent and non-coherent memory access, and two types of memory (8GB DRAM and 32MB ESRAM).

The maximum combined read and write bandwidth to DRAM is reportedly 68 GB/s (gigabytes per second), with DRAM bandwidth shared with a number of components, including CPU, GPU, display scan out, move engines and audio system.

Meanwhile, the maximum combined ESRAM read and write bandwidth is 102 GB/s, with bandwidth share between the GPU and move engines.

In addition, says VGLEaks, the two CPU modules are fully coherent, meaning they don't need to explicitly flush in order for the latest copy of modified data to be available (except when using Write Combined access).

"The rest of the Durango infrastructure (the GPU and I/O devices such as, Audio and the Kinect Sensor) is I/O coherent. The term I/O coherent means that those clients can access data in the CPU caches, but that their own caches cannot be probed," explained the VGLeaks team.

"When the CPU produces data, other system clients can choose to consume that data without any extra synchronization work from the CPU."

Meanwhile, the GPU is apparently capable of performing both coherent and non-coherent memory access. However, coherent read-bandwidth of the GPU is apparently limited to 30 GB/s when there is a cache miss, and to 10 – 15 GB/s when there is a hit.

And last, but certainly not least, the Durango console boasts 25.6 GB/s of read and 25.6 GB/s of write bandwidth shared between four move engines, display scan out and write-back, and video encoding/decoding.

Additional information about the 720's alleged memory system can be found here, on the VGLeaks website.