From Sega Retro

Naomi case.jpg
Fast facts on Sega NAOMI
Manufacturer: Sega
Variants: Sega NAOMI GD-ROM, Sega NAOMI Multiboard, Sega Dreamcast, Atomiswave, Sega Aurora
Add-ons: GD-ROM
Main processor: Hitachi SH-4
Release Date RRP Code
1998-09 ¥?  ?
1998 $1,995 [1]  ?
1998  ?

The NAOMI (New Arcade Operation Machine Idea) is an arcade system released by Sega in 1998. It was designed as a successor to Sega Model 3 hardware, using a similar architecture to the Sega Dreamcast.

The NAOMI was succeeded by the Sega Hikaru and Sega NAOMI 2 boards, though having out-lasted the NAOMI 2, Hikaru and Sega Aurora. The Sega Chihiro, or possibly even the Sega Lindbergh, could also be seen as successors.


The NAOMI debuted at a time when traditional arcades were on a decline, and so was engineered to be a mass-produced, cost-effective machine reliant on large game ROM cartridges which could be interchanged by the arcade operator. This is contrary to systems such as the Model 3, in which each board, despite sharing largely the same specifications, would be bespoke, with the built-in ROMs being flashed with games during the manufacturing process. This is not the first time such an idea was utilised by Sega, but never before had technology been used for a cutting-edge Sega arcade specification.

Unlike most hardware platforms in the arcade industry, NAOMI was widely licensed for use by other manufacturers, many of which were former rivals to Sega, such as Taito, Capcom and Namco. It is also one of the longest-serving arcade boards, being supported from 1998 to 2009. It is a platform where many top-rated Sega franchises were born, including Virtua Tennis, Samba de Amigo, Crazy Taxi and Monkey Ball.


The NAOMI shares the same basic system architecture as the Dreamcast, with both systems using the same Hitachi SH-4 CPU, PowerVR Series 2 GPU (PVR2DC), and Yamaha AICA based sound system. While the CPU of the NAOMI and Dreamcast operate at the same clock speed (clock frequency), the NAOMI packs twice as much system and graphics memory, four times as much sound memory, a higher PowerVR2 clock rate, faster VRAM bandwidth (125 MHz,[2]Media:HY57V161610D datasheet.pdf[3] compared to the Dreamcast's 100 MHz), and FPGA providing additional processing. Multiple NAOMI boards can also be 'stacked' together to achieve better graphics performance or for a multi-monitor setup.

After The House of the Dead 2, a newer revision of the PowerVR2 graphics chip was used in subsequent NAOMI systems.[2] According to VideoLogic's president and CEO, Hossein Yassaie, in September 1998: "With Dreamcast, PowerVR set out to create a new standard in 3D graphics for console gaming; now with Sega’s Naomi, we will deliver unprecedented levels of 3D performance to arcade systems".[4]

Another key difference between NAOMI and Dreamcast lies in the game-media - the NAOMI primarily uses ROM PC (printed circuit) boards (i.e. large game cartridges) with up to 168 MB of usable data (more expensive but with faster loading), while the Dreamcast uses GD-ROM optical-storage with up to 1GB of storage (at the expense of load times). The NAOMI was extended in 1999 so that it could interface with GD-ROM-based arcade games. This system uses standard PC SDR-DIMM modules which are battery backed-up for storing game data. The game data is read from the GD-ROM at bootup, stored onto the SDR RAM to which the NAOMI reads from during game. This leaves less wear on the GD-ROM drive as it's only used when the memory is empty or corrupted, else it will use the SDR RAM for boot-up every subsequent power on after checking the data integrity. If the battery fails, the system is left turned off for several days or the game GD-ROM is changed, the game will be reloaded from the GD-ROM drive.

Along with the standard version, three more variants also exist:

  • First Edition — The initial release of NAOMI hardware was housed in an aluminium shell, similar in design to some versions of the earlier Model 2 and Model 3 system hardware. This version is known to be used in House of the Dead 2 arcade machines, with the game ROM board pre-installed inside the case. It is unknown whether this is a unique hardware variant specifically for House of the Dead 2, or whether it is compatible with later NAOMI releases. This prototype uses an earlier revision of the PowerVR2 graphics chip.[2]
  • Multiboard — Several NAOMI motherboards joined onto a single board which connects the multiple boards together to created a more powerful parallel processing system.
  • Satellite Terminal — independent NAOMI cabinets connected to a master one

NAOMI boards can be used in special game cabinets (NAOMI Universal Cabinet) where a theoretical maximum of sixteen boards can be used in a parallel processing format.

The NAOMI multiboard setup uses a different BIOS chip than a regular NAOMI to handle all the boards but the whole system only uses one copy of the game cartridge, of which only four games were released.

Technical Specifications

NAOMI Specifications

See Sega Dreamcast Technical Specifications for more details on the capabilities of the general Dreamcast/Naomi hardware, though the specifications for the Naomi differ from the Dreamcast in various ways, as listed below. [2]






NAOMI GD-ROM Specifications

The NAOMI GD-ROM, released in 1999, is identical to the standard NAOMI, but uses GD-ROM discs for storage instead of ROM cartridges. It comes with a DIMM Board, which is very similar to a ROM cartridge, but with RAM instead of ROM. When a game is installed, the GD ROM content is loaded onto the DIMM Board RAM, so that the game data runs from the DIMM Board rather than the GD-ROM disc.

  • Board composition: Motherboard, Internal ROM Board, Filter Board, I/O Board, DIMM Board
  • Storage: GD-ROM disc drive @ 12× speed, 1 GB per GD-ROM disc
    • GD-ROM transfer rate: 1800 KB/sec


  • Overall memory: 66–570 MB
  • System RAM: 57,408 KB (56.0625 MB)
  • System ROM: 2048.125 KB (2.0001 MB)
  • Internal processor memory: 82,128 bytes (80.203 KB)
    • SH4: 26,178 bytes
    • PowerVR2: 6274 bytes
    • AICA: 32,780 bytes
    • I/O Board MCU: 16.5 KB
  • DIMM Board RAM: 8–512 MB DIMM SDRAM [33]


NAOMI Multiboard Specifications

The NAOMI Multiboard, released in 1999, stacks together multiple NAOMI system boards for parallel processing in a single arcade system, ranging from 2 to 16 system boards. Since the 16‑board variant is not known to have been used by any games, the following specifications are for the 2‑board and 4‑board variants:

  • Board composition: 2–4 NAOMI system boards
  • CPU: 2–4× Hitachi SH-4 @ 200 MHz
    • Performance: 720–1440 MIPS, 2.8–5.6 GFLOPS, 20–40 million polygons/sec geometry & lighting calculations
  • MCU: 2–4× Sega Custom Z80 @ 21.333 MHz (8‑bit & 16‑bit instructions @ 6–12 MIPS)
  • Sound engine: 2–4× Yamaha AICA Super Intelligent Sound Processor @ 67 MHz
    • Internal CPU: 2–4× 32‑bit ARM7 RISC CPU @ 45 MHz
    • CPU performance: 80–160 MIPS
    • PCM/ADPCM: 128–512 channels
  • GPU: 8–16 core processors (2–4 SH‑4 SIMD, 2–4 PowerVR2, 4–8 FPGA, 2–4 DAC)
    • Core units: 98–196 units (2–4 SH‑4 SIMD, 8–16 PowerVR2 cores, 86–172 FPGA units, 2–4 DAC)
  • Display resolution: 2–3 monitors, 640×240 to 2400×608, progressive scan, widescreen JAMMA/VGA
    • Internal resolution: 640×240 to 1600×1200 pixels per board
  • Geometry pipeline:
    • Geometry bandwidth: 6–12 GB/s (SH‑4 SIMD)
    • Floating‑point performance: 2.8–5.6 GFLOPS (SH‑4 SIMD)
  • Rasterization pipeline:
    • Render/Shader units: 90–180 units (6–12 PowerVR2 cores, 84–168 FPGA units)
    • Rendering bandwidth: 12–20 GB/s (2–4 GB/s PowerVR2, 10–20 GB/s FPGA units)
    • Raster operations: 3–6 billion 32‑bit operations/sec, 6–12 billion 16‑bit operations/sec, 12–24 billion 8‑bit operations/sec
  • Rendering fillrate:
    • 8–16 GPixels/s: Opaque polygons
    • 2–4 GPixels/s: Translucent polygons
  • Texture fillrate: 2–4 GTexels/s
  • Geometry performance: 46–92 million vertices/sec
  • Polygon performance:
    • 22–44 million polygons/sec
    • 18–36 million polygons/sec: Lighting, textures, trilinear filtering
    • 14–28 million polygons/sec: Lighting, textures, shadows, trilinear filtering
    • 12–24 million polygons/sec: Lighting, textures, trilinear filtering, Gouraud shading
    • 6–12 million polygons/sec: Lighting, textures, trilinear filtering, Gouraud shading, bump mapping
  • System RAM: 112–224 MB
    • Main RAM: 64–128 MB
    • VRAM: 32–64 MB
    • Sound RAM: 16–32 MB
    • SRAM: 64–128 KB
  • RAM/ROM memory bandwidth: 5–12 GB/s
  • Internal processor bandwidth: 16–33 GB/s


First Edition

Main version

List of Games


Distributed by Capcom

Distributed by Namco


Distributed by Capcom

Distributed by Taito

NAOMI Multiboard

NAOMI Satellite Terminal

Promotional material


  1. NAOMI Technical Overview
  2. 2.0 2.1 2.2 2.3 2.4 Sega NAOMI (MAME)
  3. 3.0 3.1 File:HY57V161610D datasheet.pdf
  4. 4.0 4.1 Sega Selects PowerVR Series2 as 3D Graphics Technology for New Arcade System (September 17, 1998)
  5. 5.0 5.1 File:NAOMI 1998 Press Release JP.pdf
  6. File:SH-4 Software Manual.pdf
  7. 7.0 7.1 7.2 Sega Dreamcast: Implementation (IEEE)
  8. Obsolete Microprocessors
  9. 9.0 9.1 File:TMP90PH44 datasheet.pdf
  10. 10.0 10.1 File:PIC12C508A datasheet.pdf
  11. 11.0 11.1 File:PIC16C621A datasheet.pdf
  12. Sega NAOMI (Historic MAME)
  13. File:CY2308 datasheet.pdf
  14. File:EPF8452A datasheet.pdf
  15. File:EPC1064 datasheet.pdf
  16. File:BU142 datasheet.pdf
  17. 17.0 17.1 17.2 17.3 17.4 17.5 File:DreamcastDevBoxSystemArchitecture.pdf
  18. Computer Graphics: Principles and Practice (Page 868)
  19. Floating-Point Calculations
  20. File:PowerVR2DCFeaturesUnderWindowsCE.pdf, page 11
  21. 21.0 21.1 Hideki Sato Sega Interview (Edge)
  22. File:SH-4 Software Manual.pdf, page 25
  23. File:Dreamcast Hardware Specification Outline.pdf
  24. Asian Dynamite (MAME)
  25. File:XCF01S datasheet.pdf
  26. File:HM5264 datasheet.pdf
  27. File:KM416S4030C datasheet.pdf
  28. File:HM62256B datasheet.pdf
  29. File:AT93C46 datasheet.pdf
  30. File:S29GL-N datasheet.pdf
  31. Sega NAOMI (ROM Dumping)
  32. File:DA28F640J5 datasheet.pdf
  33. 33.0 33.1 Sega NAOMI DIMM board and GD-ROM
  34. File:M366S3323CT0 datasheet.pdf
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