Editing SGI Octane (section)

===Graphics===
Graphics on the Octane are provided by a series of cards: SI, SI+T, SSI, MXI. These are updated XIO versions of Solid Impact (SI), High Impact (SI+T) and Maximum Impact (MXI) from the [[SGI Indigo2]] that were internally designated as 'MARDIGRAS'. The boards were accelerated and reengineered with faster [[geometry pipeline|geometry engine]] and [[Texture mapping|texture]] modules to create their new versions: SE, SE+T, SSE, MXE. The SI/SE provides 13.5 MB of [[framebuffer]] memory and the SSE and MXE have a 27 MB framebuffer.

The '+T' indicates an additional high speed [[RDRAM|Rambus RDRAM-based]] texture board which gives 4 MB of texture memory, which is practically indispensable, though quite expensive and fragile. The SI/SE+T has one texture board, while the MXI/MXE has two texture boards; however, the two boards in the MXI/MXE do not double the available texture memory. It instead doubles the texture performance.

Later Octanes and Octane2's support the [[SGI VPro]] graphics board series, designated 'ODYSSEY'. The first VPro series cards were the V6 and V8. The main differentiator being that the V6 has 32 MB of RAM (unlike the MARDIGRAS option, framebuffer memory and texture memory come from the same pool) and V8 having 128 MB. Later, the V10 (32 MB) and V12 (128 MB) were introduced. The main difference with the new VPro V10/V12 series is that they had double the geometry performance of the older V6/V8. V6 and V10 can have up to 8 MB RAM allocated to textures (2X more than the textured-enabled MARDIGRAS options), while V8 and V12 can have up to 108 MB RAM used for textures.

The VPro graphics subsystem consists of an SGI proprietary chip set and associated software. The chip set consists of the buzz ASIC, pixel blaster and jammer (PB&J) ASIC, and associated SDRAM.

The buzz ASIC is a single-chip [[graphics pipeline]]. It operates at 251&nbsp;MHz and contains on-chip SRAM. The buzz ASIC has three interfaces:

* Host (16-bit, 400-MHz peer-to-peer XIO link)
* SDRAM (The SDRAM is 32 MB (V6 or V10) or 128 MB (V8 or V12); the memory bus operates at half the speed of the buzz ASIC.)
* PB&J ASIC

As with the MARDIGRAS boards, all VPro boards support the [[OpenGL]] (MARDIGRAS is OpenGL 1.1 + SGI Extensions, and VPro upgraded support to OpenGL 1.2) and [[OpenGL Architecture Review Board|OpenGL ARB]] imaging extensions, allowing for [[hardware acceleration]] of numerous imaging operations at real-time rates.