GPU
 The original Xenos, Y1 | |
| Introduced | Late 2005 |
|---|---|
| Designed By | ATi Microsoft NEC (eDRAM) |
| Codename | ATi C1 |
| Type | GPU |
| Used In | Original Xbox 360 |
| Clock Speed | 500MHz |
| Memory | 10MB eDRAM |
| Successor | XCGPU |
Xenos, codenamed C1, is the graphics processor, northbridge, and memory controller used in the Xbox 360. It also has an NEC designed eDRAM which contains additional logic.
The processor was developed by Microsoft and ATi, and the first version was codenamed Y1, which stands for Year 1.
Specifications
GPU
- 500Mhz clock speed
- 48 floating-point vector processors divided into 3 dynamically scheduled SIMD groups (16 each)
- Unified shader architecture
- 16 texture addressing units
- 16 texture filtering units
- 8 pixel rendering pipelines
- Direct access to CPU L2 cache
eDRAM
- 10MB 256GB/s eDRAM
- Contains logic for:
- 4-sample anti-aliasing
- Alpha compositing
- Color
- Z/stencil buffering
Versions
Y1 (90nm)
The initial version of the GPU, known as Y1, entered production in 2005 and is used on the Xenon and Zephyr_A motherboards. Initial versions were defective while later versions became reliable.
Y2 (80nm)
In 2007, the GPU was shrunk to 80nm, while the eDRAM remained at 90nm. Known as Y2, it is used on the Zephyr_B motherboard.
Rhea (80nm)
Later in 2007, the GPU was revised with an 80nm eDRAM. Known as Rhea, it is used on the Zephyr_C and Falcon motherboards. Later versions of the chip were the first chips installed on newly produced consoles to be reliable. Multiple versions of Rhea were created as Microsoft experimentated during the attempts to make the chip reliable.
Elpis (80nm)
In 2009, fixed 90nm GPUs stopped being produced, however Microsoft still had Xenon to repair and refurbish. Since the fixed 80nm Rhea GPU was still being produced, Microsoft chose to slightly modify it in order to allow an 80nm chip to be retrofitted in place of a defective 90nm GPU. This modification to Xenon boards was known as Elpis, which served as the name of the GPU and the motherboard with this GPU installed.
Zeus (65nm)
Kronos (65nm)
XCGPU
In 2010, the GPU was shrunk to the 45nm process and combined with the XCPU processor to create a system-on-a-chip, called the XCGPU.