Gunga (65nm only)
|Original Xbox 360
The GPU, codename Xenos (later Gunga) is the graphics processor, northbridge, and memory controller used in the Xbox 360. It also contained an eDRAM daughter die that contains additional logic.
The processor was developed by Microsoft and ATi, and the first version was codenamed Y1, which stands for Year 1. The eDRAM was designed by NEC.
- 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
Later in 2007, The Y2 version 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.
In 2009, fixed 90nm chips stopped being produced, however Microsoft still had Xenons to repair and refurbish. Since the fixed 80nm Rhea chip 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 chip. This modification to Xenon boards was known as Elpis, which served as the name of the GPU and the motherboard with this GPU installed.
In 2008, the chip was redesigned for the 65nm process under the codename Gunga. The eDRAM remained at 80nm. Known as Zeus, it is used on the Jasper motherboard. It is the first chip where all variants are reliable.
- 10MB 256GB/s DRAM
- Contains logic for:
- 4-sample anti-aliasing
- Alpha compositing
- Z/stencil buffering
Styx is the redesigned eDRAM die and replaces Edifis. It was manufactured on the 80nm and 65nm processes. It is used on all versions of Rhea, Elpis, Zeus, and Kronos. It is also used on the Valhalla XCGPU.
The Winchester CGPU integrated the eDRAM into the main die. As a result, there is no daughter die anymore.