Elan Graphics
Encyclopedia
Elan Graphics is a computer graphics
Computer graphics
Computer graphics are graphics created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware....

 architecture for Silicon Graphics
Silicon Graphics
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...

 computer workstations. Elan Graphics was developed in 1991 and was available as a high-end graphics option on workstations released during the mid-1990s as part of the Express Graphics architectures family. Elan Graphics gives the workstation real-time 2D and 3D graphics rendering capability similar to that of even high-end PC
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

s made over ten years after Elan's introduction, with the exception of texture mapping
Texture mapping
Texture mapping is a method for adding detail, surface texture , or color to a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Dr Edwin Catmull in his Ph.D. thesis of 1974.-Texture mapping:...

, which had to be performed in software. http://www.obsolyte.com/sgi_indigo/

Elan Graphics systems consist of four Geometry Engines capable of a combined 128 MFLOPS and one Raster Engine. Together, they are capable of rendering 180K Z-buffered, lit, Gourad-shaded
Gouraud shading
Gouraud shading, named after Henri Gouraud, is an interpolation method used in computer graphics to produce continuous shading of surfaces represented by polygon meshes...

 triangles per second. The framebuffer has 56 bits per pixel, causing 12-bits per pixel (dithered RGB 4/4/4) to be used for a double-buffered, depth buffered, RGB layout. When double-buffering isn't required, it is possible to run in full 24-bit color. Similarly, when Z-buffering is not required, a double-buffered 24-bit RGB framebuffer configuration is possible. The Elan Graphics system also implemented hardware stencil buffering by allocating 4 bits from the Z-buffer to produce a combined 20-bit Z, 4-bit stencil buffer.http://www.sgistuff.net/hardware/graphics/documents/ElanTR.html

Elan Graphics consists of five graphics subsystems: the Command Engine, Geometry Subsystem, Raster Engine, framebuffer
Framebuffer
A framebuffer is a video output device that drives a video display from a memory buffer containing a complete frame of data.The information in the memory buffer typically consists of color values for every pixel on the screen...

 and Display Subsystem. Elan Graphics can produce resolutions up to 1280 x 1024 pixels with 24-bit color and can also process unencoded NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

 and PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...

 analog television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...

 signals. The Elan Graphics system is made up of five daughterboard
Daughterboard
A daughterboard, daughtercard or piggyback board is a circuit board meant to be an extension or "daughter" of a motherboard , or occasionally of another card...

s that plug into the main workstation motherboard
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

.

The Elan Graphics architecture was superseded by SGI's Extreme Graphics
Extreme Graphics
Extreme Graphics is a computer graphics architecture for Silicon Graphics computer workstations. Extreme Graphics was developed in 1993 and was available as a high-end graphics option on workstations such as the Indigo2, released during the mid-1990s...

 architecture on Indigo2 models and eventually by the IMPACT
IMPACT (computer graphics)
IMPACT refers to a 3D computer graphics architecture and a family of implementations of the aforementioned architecture developed and manufactured by Silicon Graphics from 1995 to 1997. Introduced on 10 July 1995, it was a high-end desktop graphics option used in Silicon Graphic's workstations...

graphics architecture in 1995. http://retrotechnology.com/herbs_stuff/indy.html

External links

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