Model 2
Arcade 3D revolution
Model 2 was Sega's Model 1 polygon engine with texture-mapping hardware from General Electric's flight-simulator division, co-developed from August 1992. It debuted with Daytona USA in 1994 at 300,000 textured polygons a second and was succeeded by the unrelated Model 3.
Model 2 was the Sega arcade board behind Daytona USA and Virtua Fighter 2: Sega’s Model 1 polygon engine with texture-mapping hardware from General Electric’s flight-simulator division bolted on. It is the reason mid-1990s arcade 3D had painted surfaces while home consoles were still learning to draw them.
Fast facts
- Partnership: Sega AM2 and General Electric Aerospace, from August 1992; the GE division became part of Martin Marietta, then Lockheed Martin.
- First game: Daytona USA (April/May 1994).
- Throughput: 300,000 texture-mapped polygons a second, against about 180,000 flat ones on Model 1.
- Display: 496×384, 65,536 colours.
- Successor: Model 3 (1996), a different design built on Lockheed Martin’s R3D/PRO-1000.
How it was built
Yu Suzuki told Edge in 1994 that the approach came from the other side: “General Electric Co. approached us because they had realtime texture-mapping ASICs and we entered a commercial partnership with them in August 1992. We co-developed the Model 2 board with them over a period of a year, and Daytona GP took a further year to develop.” Edge later filled in the rest of the story: Sega’s own engineers had “failed to make significant progress towards an advanced texture-mapping version” of Model 1, so the Americans were called in. The GE group sat in Daytona Beach, Florida, “across the street from the Daytona International Speedway”; Martin Marietta bought it after Model 1 was finished, and Martin Marietta merged with Lockheed in 1995.
The result was “a combination of Sega’s Model 1 polygon engine technology and a Martin Marietta-designed texture-mapping board”. The spec box Edge printed alongside the Suzuki interview lists a 32-bit RISC CPU at 25 MHz, 8 Mbits of RAM, up to 248 Mbits of ROM (Daytona used 178), and a 3D engine rated at 900,000 vectors and 300,000 polygons a second with flat shading, texture mapping, micro-texture and two reflection modes.
What it added
Suzuki’s own summary: “there’s obviously the texture mapping, and there are almost twice as many polygons — 300,000. But there are also special effects like the reflection of the sky in the windows of the cars — that’s all handled in hardware by separate algorithms.” He was frank about what the board did not bother with: Daytona “only uses Gouraud shading in the attract sequence — the actual game uses flat shading, which is much faster”, and he expected Ridge Racer was built the same way.
Daytona USA
Edge saw a 5%-complete demo in early 1994 and was told by one of the game’s creators that it “throws 300,000 texture-mapped and shaded polygons around every second. Enough to knock anyone’s socks off.” Model 1, running Virtua Racing and Virtua Fighter, managed “about 180,000 plain polygons a second.”
A year later, previewing the Saturn conversion, the magazine measured the gap: in the arcade the board drew “an amazing 5000 polygons per frame, every 1/60th of a second”, while AM2 was aiming for 30 frames a second at home with cars of “around 160 polygons”. The coin-op’s 496×384 display, micro-texture and reflections would all be missing.
Virtua Fighter 2
The board was revised for Virtua Fighter 2, which ran “at 60fps (twice the speed of the original)”. Edge reported the Model 2 used for it had “been speeded up and now includes extra memory, enabling the screen to draw further into the distance. This was one of the most noticeable problems that Daytona USA suffered from.”
Model 3
Suzuki was already naming the successor in June 1994: “the only one I can mention is Model 3. Compared to Model 2, this is a very high-performance board.” It was late. In October 1995 Edge reported that Indy 500 had been “originally targeted for Model 3, but delays in the board’s progress meant it was coded up for Model 2 instead”, and that the new board “has little in common with its forerunner” — it was built on Lockheed Martin’s R3D/PRO-1000 rather than Model 1’s engine. Virtua Fighter 3 was its debut in 1996. Sega’s AM3 team drew the line between the boards for Sega Saturn Magazine in 1998: “Model 2 is okay for Virtual stuff like robots and zombies”, but living creatures needed Model 3’s colour texture maps. Nor could code simply be moved across: “The Model 3 has a different Operating System (OS) to the one we used for the Model 2. We use a Windows ’95 package for the Model 3.”