TAAC-1 is an interesting and little-known piece of history. Its creators call it the first board-level GPGPU (a programmable graphics card). This thing was designed to accelerate scientific and medical visualization. It could render 30,000 3D Gouraud-shaded and Z-buffered polygons per second. In addition to that, it could also be programmed to accelerate volumetric rendering and ray tracing. The board could even be programmed in C and allowed to do more than just graphics.
The large double-plane VME board filled three slots and a half of it was covered with memory chips. There were 8MB of frame-buffer memory and the 200bit GPU logic ran at 8MHz, producing up to 1024×1024 pixels in true color. TAAC-1 was used with Sun 3 systems based on Motorola 68020 (16.67MHz).
Trancept Systems Inc. was founded in 1986 by three people. One of them was Tim Van Hook. The same person that later worked for SGI as a Principal Engineer (the architect of Nintendo 64) and started a company called ArtX (Nintendo GameCube graphics hardware), which was acquired by ATI in 2000.
Demo video: part1, part2
More info: virhistory.com, obsolyte.com