Sega Model 2

From Sega Retro

Model2 cpu.jpg
Sega Model 2
Manufacturer: Sega
Variants: Model 2A-CRX, Model 2B-CRX, Model 2C-CRX
Add-ons: DSB1/DSB2 (Model 2C-CRX)
Release Date RRP Code

The Sega Model 2 is an arcade system board originally debuted by Sega in 1993 as a successor to the Sega Model 1 board. It is an extension of the Model 1 hardware, most notably introducing the concept of texture-mapped polygons, allowing for more realistic 3D graphics for its time.

The Model 2 board was an important milestone for the arcade industry, and helped launch several key arcade franchises of the 1990s, including Daytona USA, Virtua Cop, Sega Rally Championship, Dead or Alive, Virtua Striker, Cyber Troopers Virtual-On and The House of the Dead.

Hardware

The Model 2 was designed as the direct successor to the Model 1, and like its predecessor was released as a set of printed circuit boards to arcade operators, or packaged in bespoke cabinets created by Sega.

The most noticeable improvement of the Model 2 over the Model 1 is texture mapping, which enables polygons to be painted with bitmap images, as opposed to the limited monotone flat shading that the previous board supported. The Model 2 also introduced the use of texture filtering and texture anti-aliasing,[1] as well as trilinear filtering.[2] It was the most powerful game system in its time, equivalent to the power of a PC graphics card in 1998, five years after the Model 2's release.[2]

There are in fact four versions of the system: the original Model 2, and the Model 2A-CRX, Model 2B-CRX and Model 2C-CRX variants. The Model 2 and 2A-CRX use a custom DSP with internal code for the geometrizer, while 2B-CRX and 2C-CRX use well documented DSPs and upload the geometrizer code at startup to the DSP.

According to Yu Suzuki, the Sega Model 2B-CRX arcade system board developed for Fighting Vipers "has a slightly faster processing speed" and "a higher response to displaying more polygons".[3]

Technical specifications

Model 2

  • Board composition: CPU Board, Video Board, Communication Board, ROM Board, Sound Board, Feedback Driver Board[4]
    • Revisions: CPU Board 837-10071 (50 MHz), Video Board 837-10072 (50 MHz), Communication Board 837-10537, ROM Board 834-10798, Sound Board 837-8679 (20 MHz), Drive Board 838-10646[5]
  • Main CPU: Intel i960-KB @ 25 MHz
  • Additional CPU: 2x Zilog Z80 (8/16‑bit instructions @ 1.74 MIPS)
    • Communication Board: 8 MHz[5][8] (1.16 MIPS)
    • Feedback Driver: 4 MHz[4] (0.58 MIPS)

Sound

Graphics

Graphical specifications of the Sega Model 2:[10][4][11]

Memory

  • Memory: Up to 62 MB (10,881 KB main, 35,460 KB video, 16,960 KB audio, 18 KB other)
  • System RAM: 9776 KB (9.546875 MB)[10]
  • Internal processor cache: 36.75 KB
    • CPU cache: 768 bytes[6]
    • TGP internal RAM cache: 36 KB (6 KB per TGP)[13]
  • Game ROM: Up to 54.25 MB

Bandwidth

  • System RAM bandwidth: 974 MB/s
    • Main RAM bandwidth: 112 MB/s
      • i960: 100 MB/s (32‑bit, 25 MHz)
      • Z80: 12 MB/s (2x 8‑bit, 8/4 MHz)
    • VRAM bandwidth: 883.34066 MB/s[5][16]
      • TGP: 384 MB/s (6x 32‑bit, 16 MHz)[25]
      • Video Board: 499.34066 MB/s
        • 315‑5292 & 315‑5644: 30.769232 MB/s (2x 16‑bit, 7.692308 MHz)[26]
        • 315‑5645: 28.571428 MB/s (16‑bit, 14.285714 MHz)[27]
        • 315‑5646 & 315‑5647: 400 MB/s (2x 32‑bit, 50 MHz)
        • 315‑5712: 40 MB/s (8‑bit, 40 MHz)[28]
    • Audio RAM bandwidth: 20 MB/s (16‑bit, 10 MHz)
  • Internal processor cache bandwidth: 484 MB/s
    • CPU cache: 100 MB/s (32‑bit, 25 MHz)
    • TGP internal RAM cache: 384 MB/s (6x 32‑bit, 16 MHz)
  • Game ROM bandwidth: 933–1000 MB/s (5x 32‑bit)[5][4]
    • EPROM: 133–200 MB/s (32‑bit, 33–50 MHz, 20–30 ns)[29][30]
    • MROM: 800 MB/s (4x 32‑bit, 50 MHz)

Model 2A-CRX

Model 2A-CRX, released in 1994, featured upgraded sound capabilities and increased ROM capacity:

  • Sound CPU: Motorola 68000 @ 12 MHz (16/32‑bit instructions @ 2.1 MIPS)
  • Sound chip: Yamaha SCSP
    • PCM channels: 56
    • PCM sample ROM: Up to 16 MB
    • PCM quality: 16‑bit depth, 44.1 kHz sampling rate (CD quality)
    • SCSP features: 128-step DSP, 32 PCM/FM/MIDI/LFO channels
  • Memory: Up to 142 MB (35,969 KB main, 90,244 KB video, 16,960 KB audio, 2064 KB other)
    • System RAM: 9776 KB (9.546875 MB)
      • Main RAM: 1152 KB (1.125 MB)
      • VRAM: 5984 KB (5.84375 MB)
      • Audio RAM: 576 KB
      • Other RAM: 2064 KB (2.015625 MB)
    • Internal processor cache: 36.75 KB
      • CPU cache: 768 bytes
      • TGP internal RAM cache: 36 KB
    • Game ROM: Up to 132.25 MB (34 MB main, 82.25 MB video,[31] 16 MB audio)

Model 2B-CRX

Model 2A-CRX, released in 1995, featured upgraded geometry engine DSP coprocessors and increased VRAM:[10]

  • GPU Geometry Engine DSP coprocessors: 2x ADSP-21062 SHARC @ 40 MHz[32]
    • Coprocessor abilities: Floating decimal point operation function, axis rotation operation function, 3D matrix operation function, SOC, ALU, T&L
    • Fixed-point instructions: 32‑bit instructions, 80 MIPS (40 MIPS each)
    • Floating-point units: 32/40‑bit operations, 240 MFLOPS peak (120 MFLOPS each), 160 MFLOPS sustained (80 MFLOPS each)[n 12]
    • Data bus width: 96‑bit (48‑bit each)
    • DMA controllers: 20 DMA channels (10 channels each), 80 MHz memory access (dual memory access) per SHARC, 480 MB/s transfer rate (240 MB/s each)
  • Fillrate:
    • Rendering: 152 MPixels/s (120 MPixels/s polygons,[n 13] 32 MPixels/s tilemaps)
    • Textures: 152 MTexels/s (120 MTexels/s polygons, 32 MTexels/s tilemaps)
  • Geometry calculations: 160 MFLOPS (sustained)
    • Lighting calculations: 1.7 million polygons/sec (flat),[n 14] 1.5 million polygons/sec (specular),[n 15] 1 million polygons/sec (Gouraud)[n 16]
  • Texture mapping performance: 120 MTexels/s, lighting
    • 900,000 polygons/sec: Specular, 130-texel polygons
    • 600,000 polygons/sec: Specular, 200-texel polygons
    • 300,000 polygons/sec: Gouraud shading (software), 32-texel polygons[n 17]
  • Memory: Up to 150.21 MB (35.125 MB main, 99,332 KB video, 16,960 KB audio, 18 KB other)
    • System RAM: 18,388 KB (17.957031 MB)[4]
      • Main RAM: 1152 KB (1.125 MB)
      • VRAM: 14,596 KB (1.5 MB framebuffer VRAM, 8228 KB coprocessor buffer SRAM/SDRAM, 4 MB texture SRAM/SDRAM, 64 KB luma, 32 KB geometry, 576 KB tiles, 64 KB colors)
      • Audio RAM: 576 KB
      • Other RAM: 2064 KB (2.015625 MB)
    • Internal processor cache: 512.75 KB
      • CPU cache: 768 bytes
      • DSP internal RAM cache: 512 KB SRAM (256 KB per DSP)[32]
    • Game ROM: Up to 132.25 MB (34 MB main, 82.25 MB video, 16 MB audio)
  • System RAM bandwidth: 1.111 GB/s
    • Main RAM bandwidth: 112 MB/s
    • VRAM bandwidth: 979.34066 MB/s
      • SHARC: 480 MB/s (2x 240 MB/s)[34]
      • Video Board: 499.34066 MB/s
    • Audio RAM bandwidth: 20 MB/s

Model 2C-CRX

Model 2A-CRX, released in 1996, featured an upgraded GPU chipset and optional MPEG sound boards:

  • GPU coprocessors: 2x Fujitsu TGPx4 MB86235 @ 40 MHz[10][35]
    • Coprocessor abilities: Geometry Engine DSP, Z-sorters, clipping, hardware renderers, floating decimal point operation function, axis rotation operation function, 3D matrix operation function, ALU, DMA controllers, T&L
    • Floating-point units: 32/40‑bit operations, 160 MFLOPS (80 MFLOPS each)
    • Fixed-point arithmetic: 32/64‑bit instructions, 240 MIPS (120 MIPS each)
    • Bus width: 192‑bit (96‑bit each; 64‑bit SDRAM, 32‑bit SRAM)
  • Graphical hardware features: Gouraud shading, hidden surface, Z-buffering, point sampling, bilinear filtering, trilinear filtering[36]
  • Fillrate:
    • Rendering: 212 MPixels/s (180 MPixels/s polygons,[n 18] 32 MPixels/s tilemaps)
    • Textures: 212 MTexels/s (180 MTexels/s polygons,[n 19] 32 MTexels/s tilemaps)
  • Texture mapping performance: Lighting, specular,[10] alpha blending[35]
    • 900,000 polygons/sec: 150-texel polygons[n 20]
    • 600,000 polygons/sec: Z-sorting,[n 21] 400-texel polygons
    • 520,000 polygons/sec: Gouraud shading,[n 22] 150-texel polygons[n 23]
    • 360,000 polygons/sec: Gouraud shading, Z-sorting,[n 24] 300-texel polygons
  • Optional MPEG sound board: DSB1
    • Sound CPU: Zilog Z80 (8/16‑bit instructions)
    • Sound chip: NEC µD65654GF102
  • Optional MPEG sound board: DSB2
    • Sound CPU: Motorola 68000 (16/32‑bit instructions)
    • Sound chip: NEC µD65654GF102

History

The Model 2's development was led by famed game designer Yu Suzuki and his team at Sega AM2[40] as part of a joint project between Sega, Fujitsu and GE Aerospace (acquired by Martin Marietta in 1993, now part of Lockheed Martin). Sega developed the polygon geometry engine in-house[11], using Fujitsu coprocessors DSP coprocessors that were modified with Sega's custom microcode for hardware T&L capabilities[14] (it would be years before hardware T&L would appear on consumer home systems). This was then combined with GE Aerospace's expensive texture-mapping technology,[11] which Suzuki's team condensed into a more affordable chipset.

Suzuki stated that the Model 2's texture mapping chip originated "from military equipment from Lockheed Martin, which was formerly General Electric Aerial & Space's textural mapping technology. It cost $2 million USD to use the chip. It was part of flight-simulation equipment that cost $32 million. I asked how much it would cost to buy just the chip and they came back with $2 million. And I had to take that chip and convert it for video game use, and make the technology available for the consumer at 5,000 yen ($50)" per machine. He said "it was tough but we were able to make it for 5,000 yen. Nobody at Sega believed me when I said I wanted to purchase this technology for our games."[40] Suzuki stated that, in "the end," it "was a hit and the industry gained mass-produced texture-mapping as a result." For Virtua Fighter 2, he also utilized motion capture technology, introducing it to the game industry.[41]

There were also issues working on the new CPU,[40] the Intel i960-KB, which had just released in 1993[7]. Suzuki stated that when working "on a brand new CPU, the debugger doesn't exist yet. The latest hardware doesn't work because it's full of bugs. And even if a debugger exists, the debugger itself is full of bugs. So, I had to debug the debugger. And of course with new hardware there's no library or system, so I had to create all of that, as well. It was a brutal cycle."[40]

In a late 1998 interview, Read3D's Jon Lenyo, a former employee of GE Aerospace (later Lockheed Martin), stated that Sega's development for the Model 2 can be traced back as early as November 1990, when he and other GE Aerospace employees visited Sega and demonstrated the trilinear texture filtering and shading capabilities of their technology. As Sega was already working on the Sega Model 1 internally, they eventually incorporated GE Aerospace's technology into the Model 2.[2]

The arcade board debuted along with Daytona USA, a game which was finished and copyrighted in 1993, and debuted at the Amusement Machine Show 1993[42].

Despite its high price tag of around $15,000 (equivalent to $25,000 in 2014), the Model 2 platform was very successful. It featured some of the highest grossing arcade games of all time, including Daytona USA, Virtua Fighter 2, Cyber Troopers Virtual-On, The House of the Dead, and Dead or Alive, to name a few. Sega sold over 33,000 units of the Model 2 in its first year,[43] followed by 65,000 units annually,[2] and eventually sold over 130,000 units by 1996, amounting to $2 billion revenue from hardware cabinet sales[n 25] (over $3 billion with inflation), making it one of the best-selling arcade systems of all time.

The Model 2 was succeeded in 1996 by the Sega Model 3, which in turn was succeeded by the Sega NAOMI, Sega Hikaru and Sega NAOMI 2.

List of games

Model 2

Model 2A-CRX

Model 2B-CRX

Model 2C-CRX

Other

Magazine articles

Main article: Sega Model 2/Magazine articles.

Photo gallery

  • CPU

  • Video PCB

  • A typical ROM (Virtua Cop)

  • Model 2A CPU

  • Model 2A video PCB

  • Model 2A ROM (Dead or Alive)

  • Model 2B CPU/Video PCB

  • Model 2B filter PCB

  • Model 2B communications PCB

  • A Model 2B ROM

  • Model 2C PCB

Notes

  1. ↑ [5 instructions per cycle[15] 5 instructions per cycle[15]]
  2. ↑ MAC (multiply–accumulate) operation (multiply and add) per cycle[15]
  3. ↑ [1 operation per cycle (2 cycles per MAC operation)[15] 1 operation per cycle (2 cycles per MAC operation)[15]]
  4. ↑ [400 MB/s polygon rendering bandwidth (2x 32‑bit, 50 MHz) 400 MB/s polygon rendering bandwidth (2x 32‑bit, 50 MHz)]
  5. ↑ [96 MFLOPS TGP, 13.6 MFLOPS i960 96 MFLOPS TGP, 13.6 MFLOPS i960]
  6. ↑ [TGP: 5,333,333 vertices/sec, 18 cycles (9 MAC operations) per vertex[10]
    i960: 755,555 vertices/sec, 18 floating-point operations (9 MAC operations) per vertex TGP: 5,333,333 vertices/sec, 18 cycles (9 MAC operations) per vertex[10]
    i960: 755,555 vertices/sec, 18 floating-point operations (9 MAC operations) per vertex]
  7. ↑ [3 vertices per triangle polygon 3 vertices per triangle polygon]
  8. ↑ [TGP: 1,043,478 polygons/sec, 92 cycles (46 MAC operations) per polygon[10]
    i960: 147,826 polygons/sec, 92 floating-point operations (46 MAC operations) per polygon TGP: 1,043,478 polygons/sec, 92 cycles (46 MAC operations) per polygon[10]
    i960: 147,826 polygons/sec, 92 floating-point operations (46 MAC operations) per polygon]
  9. ↑ [102 cycles (51 MAC operations) per polygon[10] 102 cycles (51 MAC operations) per polygon[10]]
  10. ↑ [TGP: 774,193 polygons/sec, 124 cycles (62 MAC operations) per polygon[10][21]
    i960: 109,677 polygons/sec, 124 floating-point operations (62 MAC operations) per polygon TGP: 774,193 polygons/sec, 124 cycles (62 MAC operations) per polygon[10][21]
    i960: 109,677 polygons/sec, 124 floating-point operations (62 MAC operations) per polygon]
  11. ↑ [163 cycles (124 cycles geometry, 39 raster operations) per polygon, 175 cycles per 4-scanline polygon (3 operations/scanline per polygon),[23][24] 271 cycles per 32-pixel polygon (3 cycles per pixel) 163 cycles (124 cycles geometry, 39 raster operations) per polygon, 175 cycles per 4-scanline polygon (3 operations/scanline per polygon),[23][24] 271 cycles per 32-pixel polygon (3 cycles per pixel)]
  12. ↑ [MAC operation (multiply and add) per cycle[33] MAC operation (multiply and add) per cycle[33]]
  13. ↑ [2 megapixels per frame 2 megapixels per frame]
  14. ↑ [46 MAC operations per polygon[10] 46 MAC operations per polygon[10]]
  15. ↑ [51 MAC operations per polygon[10] 51 MAC operations per polygon[10]]
  16. ↑ [62 MAC operations per polygon[10][21] 62 MAC operations per polygon[10][21]]
  17. ↑ [101 cycles (62 cycles geometry, 39 raster operations) per polygon, 113 cycles per 4-scanline polygon (3 operations/scanline per polygon),[23][24] 209 cycles per 32-pixel polygon (3 cycles per pixel) 101 cycles (62 cycles geometry, 39 raster operations) per polygon, 113 cycles per 4-scanline polygon (3 operations/scanline per polygon),[23][24] 209 cycles per 32-pixel polygon (3 cycles per pixel)]
  18. ↑ [94 megapixels/sec per GPU[37] 94 megapixels/sec per GPU[37]]
  19. ↑ [94 megatexels/sec per GPU[37] 94 megatexels/sec per GPU[37]]
  20. ↑ [88 cycles per polygon,[38] 266 fixed-point instructions per polygon, 450,000 150-pixel polygons/sec per GPU[39] 88 cycles per polygon,[38] 266 fixed-point instructions per polygon, 450,000 150-pixel polygons/sec per GPU[39]]
  21. ↑ [272 floating-point operations per polygon 272 floating-point operations per polygon]
  22. ↑ [151 cycles per polygon[38] 151 cycles per polygon[38]]
  23. ↑ [250,000 150-pixel polygons/sec per GPU[39] 250,000 150-pixel polygons/sec per GPU[39]]
  24. ↑ [438 floating-point operations per polygon 438 floating-point operations per polygon]
  25. ↑ [130,000 units[44] at $15,000 each[2][45] 130,000 units[44] at $15,000 each[2][45]]

References

  1. ↑ IGN PRESENTS THE HISTORY OF SEGA (page 8)
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Second Hand Smoke: One up, two down (October 22, 1999)
  3. ↑ File:SSM_UK_02.pdf, page 21
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Sega Model 2 (MAME)
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Sega PCB
  6. ↑ 6.0 6.1 File:I960 datasheet.pdf
  7. ↑ 7.0 7.1 File:80960KB datasheet.pdf
  8. ↑ http://pdf.datasheetarchive.com/indexerfiles/Scans-068/DSA2IH00225160.pdf
  9. ↑ File:ST-077-R2-052594.pdf
  10. ↑ 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 10.10 10.11 10.12 10.13 10.14 Sega Model 2 Geometry Engine and 3D Rasterizer (MAME)
  11. ↑ 11.0 11.1 11.2 File:NextGeneration US 11.pdf, page 16
  12. ↑ Sega Model 2 ROM Dump
  13. ↑ 13.0 13.1 File:MB86232 datasheet.pdf
  14. ↑ 14.0 14.1 14.2 TGP (MAME)
  15. ↑ 15.0 15.1 15.2 File:MB86232 datasheet.pdf, page 32
  16. ↑ 16.0 16.1 Sega Model 2 Video Board
  17. ↑ Sega 16‑Bit Common Hardware, MAME
  18. ↑ File:EGM US 059.pdf, page 68
  19. ↑ File:VirtuaFighter2 Model2 Flyer.pdf, page 2
  20. ↑ 20.0 20.1 Saturn maybe not so stellar (Game Zero Magazine)
  21. ↑ 21.0 21.1 Design of Digital Systems and Devices (pages 95-97)
  22. ↑ File:DaytonaUSA Model2 Flyer.pdf, page 2
  23. ↑ 23.0 23.1 Transformation Of Rendering Algorithms For Hardware Implementation (page 53)
  24. ↑ 24.0 24.1 File:32XUSHardwareManual.pdf, page 76
  25. ↑ File:TC5588P datasheet.pdf
  26. ↑ File:TC518128CPL datasheet.pdf
  27. ↑ File:MB84256A datasheet.pdf
  28. ↑ http://pdf.datasheetarchive.com/datasheetsmain/Datasheets-39/DSA-764435.pdf
  29. ↑ File:AM27C1024 datasheet.pdf
  30. ↑ File:MX27C1024 datasheet.pdf
  31. ↑ Dynamite Cop (MAME) (Wayback Machine: 2016-03-26 03:06)
  32. ↑ 32.0 32.1 File:ADSP-2106 datasheet.pdf
  33. ↑ File:ADSP-2106 datasheet.pdf, page 2
  34. ↑ File:ADSP-2106 datasheet.pdf, page 4
  35. ↑ 35.0 35.1 File:3DGraphicsProcessorChipSet.pdf
  36. ↑ File:3D-CG System with Video Texturing.pdf
  37. ↑ 37.0 37.1 File:3DGraphicsProcessorChipSet.pdf, page 12
  38. ↑ 38.0 38.1 File:3DGraphicsProcessorChipSet.pdf, page 8
  39. ↑ 39.0 39.1 File:3DGraphicsProcessorChipSet.pdf, page 11
  40. ↑ 40.0 40.1 40.2 40.3 The Disappearance of Yu Suzuki: Part 1 (1UP)
  41. ↑ Yu Suzuki recalls using military tech to make Virtua Fighter 2
  42. ↑ File:EGM US 051.pdf, page 222
  43. ↑ Press release: 1995-03-20: Lockheed Martin 3D Graphics Accelerator offers real-time PC visual system performance
  44. ↑ Sega Enterprises (Real3D)
  45. ↑ Early concept of Daytona USA at Summer CES 1993


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