The original Impact graphics options (code name "Mardi Gras") have been introduced for the R4x00, R8000 and R10000 Indigo 2 graphics workstations. This level of the Impact graphics technology were also used on the SI, SSI, MXI Octane graphics options. They have been obsoleted by the second generation impact graphics options (SE, SSE, MXE).



While the Impact graphics option for Indigo 2 and Octane share the same technology, physically they are two different things. In Indigo 2 systems the graphics options are attached to the systems GIO64 bus, in Octanes the XIO expansion bus is used to attach graphics. The form factor is completely different. Indigo 2 boards are somewhat similar to PC cards (ISA/EISA) and the graphics option can be a set of various boards. Octane graphics options are always single boards in either single or double width.

Indigo 2

  • HQ3 Command Processor
    • Distribute graphics primitive to Geometry Engine
    • 267MB/sec GIO64 bus interface
    • Pixel DMA Engine
    • 300,000 gates
  • GE11 Geometry Engine
    • Transforms 3D geometry
    • Performs convolutions and other 2D imaging operations
    • 960 MFLOPS total processing power
    • 600,000 gates each
  • RE4 Raster Engine
    • Enable high-performance pixel-fill
    • 240M pixels/sec fill rate
    • 300,000 gates each
  • PP1 Pixel Processor
    • Provide blending, depth, and dithering
    • 295,000 gates each
  • RDRAM Framebuffer
    • High-bandwidth configurable frame buffer
    • 32-bit double buffer with 24-bit Z-buffer and 8-bit stencil at 1280x1024 resolution
    • High-color resolution; Up to 12-bit per component at 1280x1024 resolution
    • Up to 1600x1200 screen resolution
  • TE Texture Engine
    • Fill, warp, and zoom images/texture data
    • 119M pixels/sec texture fill rate
    • Fast texture load capability
    • 295,000 gates each
  • Texture Memory
    • Interpolates image/texture data and performs MIP-mapping interpolation
    • 1MB of texture memory expandable to 4MB through optional daughter card
    • 60,000 gates and 8Mb DRAM for each MB


Initially Octane systems were shipped with first generation Impact graphics (SI/SSI/MXI) which are based on exactly the same graphics technology as the old Impact options for Indigo 2. On later systems an enhanced level of Impact graphics (SE/SSE/MXE) was used, which features different (newer) ASICS and thus reaches a higher level of performance. The second level Impact options for Octane sometimes are referred to as ESI/ESSI. Technology wise SE equals ESI and SSE equals ESSI.


Indigo 2 Impact

All Impact graphics options for the Indigo 2 have a single GIO64 interface. While the lowend Solid Impact is just one board, the higher end variants span more than one board. The table below gives a short overview of the main indigo 2 Impact variants.

The boards column should be self explanatory, the following ones give the number of the relevant ASICs present in the graphics option. The TRAM column gives the amount of TRAM that may be installed.

  Boards HQ3 GE11 RE4 PP1 TE TRAM
Solid Impact MG10 1 1 1 2 0 -
High Impact RA2, GD 1 1 1 2 1 1 or 4 MB
Maximum Impact RA2, RB, GD 1 2 2 2 1 1 or 4 MB


The following table gives an overview of the various first and second generation Impact graphics options offered for the Silicon Graphics Octane.

The texture RAM line refers to the presence or absence of TRAM modules, single/double refers to the board size as well as the number of raster processing units.
Double boards require two TRAM modules as an texture RAM upgrade which results in higher texture performance.

1st Generation 2nd Generation
Texture RAM No Yes No Yes
Single SI SI+Tex SE SE+TEx


Indigo 2

The Impact graphics option for the Indigo 2 consists of one to three GIO64 boards. In general they can be installed in any empty slot but it is important to keep in mind that on each logical GIO64 bus only one device may be installed. In systems with additional GIO64 options the choice of slots to install the graphics options in may be limited.


The Impact class options for the Octane are XIO boards. The single width boards can be installed in any of the four available XIO slots. The double width boards physically can only attach to one XIO slot blocking the access to the one above/below it.


Indigo 2 - High Impact

High Impact graphics, RA2 board.

High Impact graphics, GD board.

High Impact graphics, GD board.

Indigo 2 - Maximum Impact

Indigo 2 Maximum Impact, RA2 board.

Indigo 2 Maximum Impact, RB board.

Indigo 2 Maximum Impact, GD board.

Octane - SE and SSE

SSE graphics board for Octane.

SE graphics board for Octane.