Sega NAOMI logoThis is the first in a series of articles about the Sega NAOMI system. Later posts will cover the hardware (I just love taking things apart :P), connecting the NAOMI to JAMMA cabinets, setting up the NAOMI with a GD-ROM and netbooting (loading games from a server).

The Sega NAOMI (New Arcade Operation Machine Idea), first shown at JAMMA in September 1998, is the successor to the Sega Model 3 platform.

Sega Naomi System

It’s based on the same hardware components as the Dreamcast game console. Though the NAOMI has twice the amount of system memory and video memory and four times as much sound memory as the Dreamcast. Multiple units can be linked to improve graphics performance or to support multiple monitors. The NAOMI Universal Cabinet was developed specifically for the NAOMI system and can house up to 16 units.


Sega Naomi GD-ROM reader

Another key difference between the NAOMI and the Dreamcast is how the game media is handled. The Dreamcast streams the data from the GD-ROM while the NAOMI arcade boards features 168 MB of solid state ROM or GD-ROM’s using a DIMM board and a GD-ROM reader. The contents of the disc is downloaded onto the DIMM board’s RAM on start up. Once the disc has been read the game is run from the RAM for better performance and reducing the mechanical wear on the GD-ROM reader.

Even if the system is turned off the game will load from the RAM when powered on again. Only if the game data in the RAM gets corrupted of if the system’s been powered off for about 72 hours the game will again have to be read from the GD-ROM.


Unlike Sega’s previous arcade platforms the NAOMI was widely licensed for use by other game publishers. Besides Sega about 20 companies has produced titles for the NAOMI system including Capcom, Namco Bandai, Tecmo, Cave, Sammy, SNK, Jaleco and Koei.

Taito launched their G-Net system (based on Sony’s PlayStation hardware) the same year as the NAOMI and, as Sega, tried to license it widely to developers. While the NAOMI became a huge success the G-Net never really made it and only some 20+ titles were ever released for the G-Net.

Connecting the NAOMI to JAMMA

Capcom I/O AdapterThe NAOMI uses the newer JAMMA Video Standard (JVS) for I/O. The JVS uses a USB A port for inputs and VGA for video output. The NAOMI is able to output graphics in VGA and CGA resolutions. There are three different I/O boards available for interfacing the NAOMI with JAMMA setups. Two were manufactured by Sega and another from Capcom.

The Capcom JVS/JAMMA converter is preferable since it offers a voltage converter for the needed 3.3 V line, and audio amplifier with volume control, the JAMMA connector and a JAMMA+ kick harness compatible with CPS2 and CPS3 games.


  • The Atomiswave system from Sammy is based on NAOMI hardware.
  • Theoritically a 16 board NAOMI system could do (16 x 3.5 mpps) = 56 million polygons/second. In reality it won’t manage more than around 20 to 30 mpps.
  • Naomi is a Japanese female name that translates to “above all beauty”.

System Specifications

CPU Hitachi SH-4 32-bit RISC CPU (200 MHz 360 MIPS / 1.4 GFLOPS)
Graphic Engine PowerVR 2 (PVR2DC)
Sound Engine ARM7 Yamaha AICA 45 MHZ (with internal 32-bit RISC CPU, 64 channel ADPCM)
Main Memory 32 MByte
Graphic Memory 16 MByte
Sound Memory 8 MByte
Media ROM Board (maximum size of 172MBytes) / GD-Rom
Simultaneous Number of Colors Approx. 16,770,000 (24bits)
Polygons 2.5 Million polys/sec
Rendering Speed 500 M pixel/sec
Additional Features Bump Mapping, Fog, Alpha-Bending (transparency), Mip Mapping (polygon-texture auto switch), Tri-Linear Filtering, Anti-Aliasing, Environment Mapping, and Specular Effect.

Game List

Game lists for the NAOMI system are available at

More info


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