IMPACT (computer graphics)
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IMPACT (sometimes spelled Impact) is a computer graphics architecture for Silicon Graphics computer workstations. IMPACT Graphics was developed in 1995 and was available as a high-end graphics option on workstations released during the mid-1990s. IMPACT graphics gives the workstation real-time 2D and 3D graphics rendering capability similar to that of even high-end PCs made well after IMPACT's introduction. IMPACT graphics systems consist of either one or two geometry engines and one or two raster managers in various configurations [1].
IMPACT graphics consists of five graphics subsystems: the command engine, geometry subsystem, raster manager, framebuffer and display subsystem. IMPACT graphics can produce resolutions up to 1600 x 1200 pixels with up to 36-bit color [2] and can also process unencoded NTSC and PAL analog television signals.
IMPACT graphics subsystems come in three configurations for SGI Indigo2 IMPACT workstations: Solid IMPACT, High IMPACT, and Maximum IMPACT. The equivalent configurations also exist for the SGI Octane workstation but are referred to as SI, SSI, and MXI (I-series), though the Octane options either had zero or 4 MB TRAM (Texture RAM), compared to High/Maximum IMPACT in Indigo2 which could have 1 MB TRAM. There was also no equivalent of SSI for Indigo2. The Octane options are the same architectural designs, but built with completely different board layouts. All the designs for Indigo2 and Octane are referred to as the MGRAS series graphics options. Later Octane workstations used a similar configuration but with updated ASICs and are referred to as the SE, SSE, and MXE (E-series). MGRAS uses Rambus RDRAM for texture memory. [3]
IMPACT uses the GE11 and GE12 geometry engines. The GE11 was used in all the Indigo2 options and the SI, SSI and MXI. The GE12 was used in the SE, SSE and MXE options. The GE11 can achieve 480 MFLOPs (960 MFLOPs in the SSI and MXI as they both use two GE11s) and the GE12 is rated for 672 MFLOPs (1.344 GFLOPs in the SSE and MXE as they both use two GE12s).
The IMPACT graphics architecture was superseded by the SGI VPro graphics architecture in 1997.
