Sega’s answer to Namco’s System 22 board, and their first capable of 3D texture mapping rendering.
Model 2 uses six (or five, according to different sources) Fujitsu MB86234 ‘TGP’ digital signal processors to generate the polygons needed for the 3D graphics. They are then sent to the 3D acceleration hardware that performs the 3d effects such as texture mapping. The TGP processors act very similar to the GTE in the original Playstation, or the vector units in the Playstation 2,where they generate the raw polygons for the 3D accelerator. Like the Sega Saturn console, the system uses quad based rendering, as opposed to triangle based rendering. Early PC 3D accelerators had a similar design concept, however instead of using DSP like chips, the FPU of the CPU was used instead, this would be the case until the release of the Nvidia GeForce in 1999, which came with its own dedicated T&L engine for geometry.
The 3D hardware was developed by Lockheed Martin, who would also provide the chipset for Sega’s Model 3 board. Martin Marietta had previously used this technology for military simulators, and were seen as a competitor to Silicon Graphics in the workstation graphics market. Compared to the TR3 chip used in System 22, the Model 2 was capable of more polygons and texture filtering, but lacked support for gouraud shading, and games typically ran at a lower resolution, although the latter could have been a design decision by Sega, or to retain compatibility with certain cabinets.
Sound hardware remains unchanged compared to the Sega Model 1, with dual Yamaha processors providing the audio, one of sound and speech effect with the other being used for background music.
A System 24 based tilemap layer is used for the 2D graphics portion, this is used for the HUD (Heads Up Display) all 3D games, as the 3D hardware was dedicated for 3D functions.
The central processing unit used was the Intel i960 running at 25Mhz, which was a departure from the NEC and Motorola based processors Sega had used previously in their arcade boards, and was different from the Hitachi SH2 processor used in the Saturn. As the processor was releavily new on the market. Sega had to debug the processor for use with their own development tools.
Funding a Revolution – Google Books
A revision of the original Model 2 design but with some improvements. The sound hardware was upgraded to use the Sega Saturn sound processor (SCSP). The 3D hardware remained unchanged however, with the System 24 tile map being used (Unknown how similar to the Sega Saturn graphics hardware, considering the Saturn VDP was based off Sega’s 2D hardware)