IMPACT (computer graphics)
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 Engines in various configurations [1].
IMPACT graphics consists of five graphics subsystems: the Command Engine, Geometry Subsystem, Raster Engine, 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 4MB TRAM, compared to High/MaxIMPACT in Indigo2 which could have 1MB 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 [[application-specific integrated circuit|ASIC]] chips and are referred to as SE, SSE, and MXE (E-series). MGRAS uses Rambus RDRAM for texture memory. [3] The Geometry Engines used were called GE11 and GE12. GE11 for Indigo2 boards and Octane SI,SSI and MXI, GE12 was used with SE,SSE and MXE GE11 is rated for 480Mflops (960Mflop in the SSI and MXI, they both use 2 x GE11) GE12 is rated for 672Mflops (1.344Gflop in the SSE and MXE, they both use 2 x GE12) GE12 in InfiniteReality (IR) for Onyx1 is rated for 640 MFLOPs (4 GEs = 2.56GLFOPs total) Renamed GE14 for use with IR in Onyx2, it is rated at 540MFLOPs (4 GEs = 2.16GLFOPs total) Precise data is not available for IR2, IR2E, IR3 and IR4, though IR2E was stated to be 13% faster than IR2.
The IMPACT graphics architecture was superseded by the SGI VPro graphics architecture in 1997.