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How to dump GD-ROMs for MAME emulation (part 2)

Dreamcast's profile picture
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Dreamcast
 · 4 Feb 2018
How to dump GD-ROMs for MAME emulation (part 2)
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Now put in the httpd-ack CDR you burned and boot it up on the DC,

How to dump GD-ROMs for MAME emulation (part 2)
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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 192.168.0.10, with subnet mask 255.255.255.0. 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 192.168.0.10. Set the Gateway to 192.168.0.1
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 http://192.168.0.100
This is the IP address we set the BBA to!

You should see some activity on the TV screen in httpd-ack

How to dump GD-ROMs for MAME emulation (part 2)
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and then you will see a listing similar to this in your browser.

How to dump GD-ROMs for MAME emulation (part 2)
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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!

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