Sega Naomi and Naomi 2 Hardware Information

The original Naomi is the arcade version of Sega Dreamcast. It has twice the graphics and system memory compared to the console and 4 times the audio memory. The reason for such a jump in audio memory is because the system does not stream cd audio off of a disc like the dreamcast but rather it runs the audio off of the rom chips or dimm board. Speaking of which, the Naomi games come in two forms. Some games will come as a rom cartridge and some games will come on GD-Rom disc which require a dimm board and gd-rom drive.

A Naomi System with Cartridge (Virtua Tennis)


The Rom cartridges are large rectangular cartridges with the name of the game on the top and 3 connectors on the bottom where the cartridge connects to the board. The benefit of this format is there is almost no load time since the game does not have to be read from an optical disc like its console brother.

A Naomi Cartridge (Dead or Alive 2):


The GD-Rom games do not work the way you would think. On the Sega Dreamcast the game would be read and loaded off of the GD-Rom disc in real time, however on Naomi to save on load times, when the system is loaded the entire game is loaded onto the dimm board. Think of the dimm board like a Naomi cartridge that instead of having permanent rom chips it has fully rewritable ram. Once the game is loaded into this dimm board the gd-rom drive shuts down and just like the cartridge games, there is almost no load time once in game. Loading a game from gd-rom to dimm board can take about 3-5 minutes depending on the size of the game. In order for the game to be loaded you must insert the proper security key chip into the dimm board, if the wrong chip or no chip is inserted the system will display an error code and not load. Dimm boards have a battery pack which makes them able to keep the game saved in the dimm board for 72 hours with the arcade machine off. Unfortunately these days the battery packs are either rare or expensive and most operators opt to just let the game load every time. As long as the cabinet/system is not turned off even with a dead battery the game will continue to run.

A Naomi GD-Rom Game (Guilty Gear XX)


A Naomi GD-Rom Drive


As far as input goes, like the 246, The Naomi uses JVS I/O boards plugged into the usb like connector. There are a few boards this system can use depending on the game you are running. For standard games that use just a joystick and 1-6 buttons a Sega JVS to Jamma I/O will work just fine. Some people prefer the more expensive Capcom I/O board but for 2 player games that just use standard joysticks and buttons (no excessive analog controls), the Sega board is inexpensive and works just fine.

Sega JVS to Jamma I/O Board


The board will connect directly to the 6 and 8 pin plugs of a JVS power supply which when used at home will either need an adapter or to be modified in order to connect it to the wall outlet. When using the GD-Rom drive you will need a splitter which either connects to the 8 pin as a pass through or connects to the smaller connector. Your GD-Rom drive will connect to the dimm board with a normal SCSI cable. The video can be connected directly to the vga plug on the front and will output to any vga compatible monitor as long as dip switch number 1 is set to the up position. The audio is connected into standard red & white composite audio plugs like most jvs systems and of course is unamplified so an audio amp in an arcade cabinet or amplified speakers will be needed to hear the audio properly. Unlike other JVS systems the Naomi only has one VGA port and one set of audio jacks (most jvs systems have 2 of each for vs play).

Front of the Naomi (showing filter board)


JVS Power Supply with the 3 Mentioned Plugs


The Naomi 2 is an upgraded version of the original Naomi. It has dual processors and dual graphics chips. It has the same amount of system memory as Naomi but double the graphics Memory, having 32Mbyte for each GPU. Each graphics processing unit renders one half of the screen. The best part about this system is it is fully compatible with all original Naomi cartridge and GD-Rom games along with having its own graphically enhanced games. Of course it goes without saying that a Naomi 2 game will not work in an original Naomi system. All interface and connections are exactly the same as the original Naomi so upgrading from a Naomi to Naomi 2 is very easy. The original Naomi cartridge games are the white/cream color that matches the system where as the Naomi 2 cartridges are the grayish beige that matches that system. The GD-Roms will be noted as working only on Naomi 2 on such games like Initial D, Beach Spikers, Virtua Fighter 4 and Virtua Striker 3.

A Naomi 2 System with Dimm Board


A Naomi 2 Cartridge (Club Kart European Session)


Some games such as Initial D need more analog inputs then a standard I/O can provide. Infact the game will not even boot unless a Sega JVS Type 1 I/O is present, the system will just reset without that board. Since Initial D uses a few more analog controls (Steering wheel and pedals) then the normal I/O could handle that is why it is locked out in such a way. I will have more on Initial D on its own page.

Sega JVS Type 1 I/O Board (type 1)


The one of the last Naomi topics (for now) that I would like to discuss is region protection. For the most part, most Naomi and Naomi 2 games will work just fine regardless of the bios that your system has installed. However, certain games will only run on certain Bios. For instance, Initial D english versions require either USA or Export Bios and will not run on Japan bios. Games such as Virtua Fighter 4 Evolution (Ver B), Capcom VS SNK Millennium Fight 2000 Pro, Melty Blood Act Cadebza, Guilty Gear XX #Reload and Street Fighter Alpha 3 Upper will only run on Japan bios. Other then the region restrictions there are some games that will not only fully translate themselves but also change their name depending on the bios. Moero! Justice Gakuen (Japan Bios) will change to Project Justice on USA or Export Bios just like Gunspike (Japan Bios) will become Canon Spike using USA or Export Bios. The best part is that the bios chip is socketed so no soldering or desoldering is required to switch it out.

One last thing that often gets people confused is that some Naomi games are able to use Dreamcast controllers. Not too many games support them and you must have a Japanese Bios installed. The only game that I have come across that will work in USA bios with the controller is Mobile Suit Gundam Federation vs Zeon (and the DX Version). Capcom was a company who supported this feature a good deal, infact many of their cabinets have a controller port right on the control panel. Games such as Moero! Justice Gakuen, Marvel Vs Capcom 2, Street Fighter Alpha 3 Upper, Gun Spike and Power Stone all support this feature in Japan bios. Games such as The Typing of the Dead, Lupin III The Typing and La Keyboard can use a Dreamcast keyboard using this same port. The filter board (that board on the front with all the ports) has pin headers marked CN6 and CN7. The first five pins of each of these are for the controller adapter. The official adapter that would come off of a control panel will be a full JST (Japanese Solderless Terminal) connector going across all pins even the unused ones. You however can get a 5 pin JST nh connector and splice it to a dreamcast extension cable eliminating the need to hack up any Dreamcast controllers and giving you the ability to swap in a Keyboard if you plan to play those games. Some games such as Moero! Justice Gakuen even have the ability to share data from the Dreamcast (Japanese of Course) to the Arcade Version. In this game your custom character made in the console version can be used in the arcade version if you bring your controller and memory card.

Dreamcast controller ports in a Japanese arcade: