According to a leaked document, credited to Pete Isensee at the Xbox Advanced Technology Group, XBox 2 will be powered by three 3.5+ GHz IBM PowerPC cores, built onto one silicon die and a 500+ MHz ATI graphics processor. XBox 2 will have 256+ MB of unified memory and run a custom operating system based on Microsoft Windows NT, similar to the Xbox operating system. The graphics interface will be a superset of Microsoft Direct3D version 9.0.
The document itself, emailed to xbox-scene.com, is careful to mention that the speeds of the CPU and GPU cores and the amount of memory are subject to change since it claims Microsoft has not yet settled on those matters. The reason many believe this document may be an official accident, is that it doesn't answer the burning RAM and storage questions. Especially when discussing the existence of a hard drive the document even tries to promote alternatives such as networked PCs, XBox Live and removable devices. It does however state that even if a hard drive is not included with XBox 2, one will be available as an extra.
Whatever the origins of this document experts have confirmed that even if it's not authentic it still, pretty much, describes XBox 2.
CPU
According to the leaked information the 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. One interesting feature will involve the 1-MB L2 cache which will be shared by the three cores. The L2 cache will be directly readable from the GPU, allowing the GPU to consume geometry and texture data from L2 and main memory simultaneously.
Graphics
The ATI manufactured GPU will share the 256 MB memory with the XBox 2 system but will also have access to 10+ MB of fast embedded dynamic RAM (EDRAM), directly on the GPU die. Along with the extremely fast EDRAM, the GPU will also include hardware instructions for alpha blending, z-test, and antialiasing.
XBox 2 will not only support high-level shading language (HLSL) model 3.0 for vertex and pixel shaders but will also include advanced shader features well beyond model 3.0. XBox 2 shaders will also have the unique ability to directly access main memory, allowing techniques that have never before been possible.
Memmory and Bandwidth
XBox 2 will have 256+ MB of unified memory, equally accessible to both the GPU and CPU. The main memory controller will reside on the GPU (the same as in the Xbox architecture). It will have 22.4+ GB/sec aggregate bandwidth to RAM, distributed between reads and writes. Aggregate means that the bandwidth may be used for all reading or all writing or any combination of the two. Translated into game performance, the GPU can consume a 512×512×32-bpp texture in only 47 microseconds.
The front side bus (FSB) bandwidth peak wil be 10.8 GB/sec for reads and 10.8 GB/sec for writes, over 20 times faster than for Xbox. Note that the 22.4+ GB/sec main memory bandwidth is shared between the CPU and GPU. If, for example, the CPU is using 2 GB/sec for reading and 1 GB/sec for writing on the FSB, the GPU has 19.4+ GB/sec available for accessing RAM.
Storage
Storage
Xenon console (XBox 2) games will have access to a variety of storage devices, including connected devices (memory units, USB storage) and remote devices (networked PCs, Xbox Live). At the time of the document, the decision to include a built-in hard disk in every Xenon console had not been made. If a hard disk is not included in every console, it will certainly be available as an integrated add-on component.
Xenon will support up to two attached memory units (MUs). MUs are connected directly to the console, not to controllers as on Xbox. The initial size of the MUs is 64 MB, although larger MUs may be available in the future. MU throughput is expected to be around 8 MB/sec for reads and 1 MB/sec for writes.
The Xenon game disc drive will be a 12× DVD, with an expected outer edge throughput of 16+ MB/sec. Latency is expected to be in the neighborhood of 100 ms. The media format will be similar to Xbox, with approximately 6 GB of usable space on the disk. As on Xbox, media will be stored on a single side in two 3 GB layers.
Controllers
Xenon will support up to four controllers. The standard Xenon controller will have a look and feel similar to the Xbox controller. The primary changes are the removal of the Black and White buttons and the addition of shoulder buttons. The triggers, thumbsticks, D-pad, and primary buttons are essentially unchanged. The controller will support vibration.
Audio - Input/Output
The document goes on to discuss the amazing audio capabilities of the system and the USB 2.0 ports and the Ethernet 10/100-BaseT port.
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