The Guru is proudly supported by....
This article is Copyright 'The Guru' 2009. You may not copy any portion of this for your own web site or printed publication without my explicit permission.

H O W   T O   D U M P   G D R O M S

This page explains in detail how to dump GDROMs for use explicitly with MAME emulation. While there may be other 'Dreamcast Purists' that might think otherwise, this is how it will be done for MAME.
Dumping GDROMs is not trivial. You will need to invest in some items that are not cheap and not widely available now. Once you are set up and everything is working properly, it is very simple to dump any GDROM disc in 20 minutes.

To dump GDROMs you need ALL of the following.....

  • A working Sega Dreamcast. A modchip is required if it was one of the last ones made in Japan as those were updated to not boot CDRs. Otherwise a regular DC will do fine.

  • A network cross-over cable. Not straight, we need it twisted, like what is used to connect 2 PCs directly together. They are usually red or yellow. The blue ones are straight through for connecting a PC via a router or network hub and are no good for this purpose. I believe you can connect the DC via a straight through cable to a router but I'm not going there. YMMV

  • BBA (stands for Broad Band Adapter). Sega made these to connect the DC to broadband for internet. They are a must for dumping GDROMs. They are HIGHLY sought after now for obvious reasons and can go for upwards of US$200 _IF_ you can get one. The serial cable method is useless. I don't think you want to wait 24 hours for 1GB of data to be downloaded serially. In any case, that method is not detailed here, so you're on your own if you want to use a serial cable (also known as a 'coders cable')

  • Broadband Passport GDROM (or burned CD). This is the software that allows you to set the IP address of the BBA to a fixed address. It usually came with a BBA when it was purchased but you can get a version off the internet if you look. My version comes up on the DC Memory Unit as 'Broadband Passport US BETA 1'. I may make an ISO available if enough people request it, although the number of people that would want to and can actually complete all these 'required parts needed' steps will be quite low.

  • Dumping s/w for the DC called 'httpd-ack' on a DC-bootable CDR. Again, I can make this available if there are many requests but it is available on the net if you search for it. It is currently available here although I can't guarantee the location of that file will be available at this link in the future. The main site is

  • A decent PC with at least 1GB of free HDD space for each game you dump.

  • Any common browser, pointed to the IP of the BBA (i.e. I use Linux and Firefox because I'm sick of the Microsoft Propoganda Machine messing with my PC, but also it was more stable. In Windows it kept disconnecting for some unknown reason. It might work for you with XP or Vista. I was using a laptop, but a desktop is probably better but I didn't have a desktop PC and a TV near each other so I used a laptop :-)

  • A recent release of MAME complete with all files included. We need a file called 'CHDMAN.EXE'

OK, so let's start.

Extract httpd-ack from the zip you downloaded and burn the CDI file with DiscJuggler or Alcohol120%.

Use a Dreamcast web browser (i.e. Passport) to set up the BBA connection options. You must set up the BBA to use static IP settings, not DHCP. We'll do that now. Boot it up on the DC.

On the DC controller, press the left button under the controller and a menu will pop-up.

Select OPTION and you will be presented with the following screen



and enter the IP address shown using the on-screen keypad. Select EXIT to go back to the previous screen.

Move down to GATEWAY and enter the numbers shown

Select EXIT to go back to the previous screen,

then select FORWARD to continue.

Select FORWARD 3 more times as those screens don't need to be changed.
Select OK on this screen

Whereby you will see a message telling you the settings have been saved

You do not need to repeat the config part once it is done. This is a one-time thing, unless you want to change the IP settings inside the BBA.

Now put in the httpd-ack CDR you burned and boot it up on the DC,

then remove the CDR and then just let it sit there for now.

Now boot up your PC. You'll need to set the PC network card to some address in the same range as the BBA like, with subnet mask These settings can be found in (XP) 'Control Panel->Network Connections->Local Area Connection->General->Internet Protocol (TCP/IP)->Properties->Use the following IP address' then set the IP address to Set the Gateway to
Click OK to save the settings
NOTE! If you want to use your PC to access the internet normally afterwards, you will need to remove the static IP address settings after you have dumped the GDROM discs otherwise you will not be able to get any internet connection from your ISP. Just set it to default, or auto, or dhcp etc. and all should be well.
Close all of the windows and wait for the IP to renew itself. You may need to reboot Windows in order for it to see the new IP address.

Next, put a SEGA GDROM into the DC and close the lid. Wait a few seconds for it to spin up and read it.
Load your favorite browser and in the top address bar, type
This is the IP address we set the BBA to!
You should see some activity on the TV screen in httpd-ack

and then you will see a listing similar to this in your browser.

From here on it's VERY easy. Click the link 'track01.bin' and save it to the HDD. Repeat and save 'track02.raw' and 'track03.bin'. Tracks 01 and 02 will be saved quickly, track03 will take approximately 20 minutes to download. Also be sure to save 'disc.gdi' because this is used to make our CHD for MAME and also save the html file for added documentation! It's also a good idea to save these 5 files into a separate directory for each GDROM you read or you'll get them mixed up.

Please don't hack the track03.bin image to ~200M because you think that's all that is needed for DC emulators. MAME IS NOT A DC EMULATOR. The tracks on a NAOMI GDROM are padded and MUST be at the correct sector location or the game will not work. Track03 is padded to be around 1130.8MB. The NAOMI hardware checks to make sure the tracks are located where it expects them to be and if you hack it, it will not be accepted!

That's all for the dumping process, the disc is now dumped, properly. It has been proven that no SEGA NAOMI GDROM game uses sub-channel data, so just don't bother trying to convince anyone it is needed because no one from MAMEDEV is listening.

If you want to dump more discs, just put them into the DC, one by one, hit 'refresh' in your browser and then save the 4 files listed above and the html for each game.

If you are just dumping something new for MAME, just zip or rar the files and put them online somewhere and send me a link to it so I can download it.

This next part is optional to the dumping process....
To create a CHD for MAME, copy the CHDMAN.EXE from any recent MAME distribution to the directory where you saved the GDROM images. Now bring up a command prompt, change directory to that dir and type
chdman -createcd disc.gdi gdl-0007a.chd

The disc.gdi is specific for each game you dump so don't mix them up! The gdl-0007a.chd is the file name of the CHD we want to create. Please be sure to name them properly based on your actual GDROM disc! Each Sega GDROM has a number printed on the front the the disc. See my NAOMI Dump Status page for a complete listing. Use those numbers!

One final note, each game is protected with a key chip. This is a PIC16C622A and can not be copied. It is critical that we get a dump of the decryption key contained in these chips or the emulation will go nowhere. There are a few people in different countries who now have the capability to dump out the key, including me (see my news for info and pics of the cracking gizmo), a few other MAME-devs and a couple of non-devs. If you have access to the key chips and are able to loan them out, please contact me so we can get a dump of them!

That's it! Now go do some dumping and send us some good stuff!

This article is Copyright 'The Guru' 2009. You may not copy any portion of this for your own web site or printed publication without my explicit permission.

Want to see more games in MAME? Please consider donating funds