I recently finished my Namco System 1 game exchanger project and I'm pretty happy of it 
For info I’m not a pro in electronics, it took me a while to do it and there might be better ways to do it. My main concern in this project was to not harm the board in any way. No solder, no cut trace or whatever.
At the beginning I just wanted to put some ZIF sockets on every socket to swap game quickly. But the roms are so close to each other than it's seemed not to be a good idea.
I searched a bit more and realized that a lot of roms share the same data bus and address bus, which means that I can put the code into a single bigger rom and spare a lot space! I just needed to take the Chip Enable signal of every rom and redo the addressing with TTL. Here is my first test done with proto boards on the OBJ bus.
It’s quite a mess but it works !
I did all of the 6 adapters and here is the full prototype done :
To change game I just need to swap the six roms, easy and quick!
But I had some issues on the program bus, and I realized after that photo that it was because of the inverted A16 on the PRG 7 rom. I had to add an extra TTL to deal with it (like for the VOI 0). I redid the PRG adapter and learned how to use kicad to print my first small PCB! Of course I did a mistake
I put the wrong hole size so I couldn’t put a ZIF in it. But anyway it worked well with a regular socket.
After that last modification I was able to do serious tests. I only own a Splatter house and a Dangerous Seed, so I used the decrypted roms done by jrock to test my work with the maximum games as possible. And the results were excellent: all 12 decrypted games worked perfectly, as well as Splatter House and Dangerous Seed using the original code and their custom key. Youkai Douchuuki worked also great as it doesn’t require any key.
From here I decided to design some cleaner PCBs and here is the final result:
I will probably do a last adapter to have the custom on ZIF socket too. It’s way beyond my first expectation and is totally enough for my personal usage, so I won’t go any further. A real multi won’t be hard to do for an experienced guy, that’s for sure. There is still the problem of non-decrypted games, to my knowledge only 12 has been done by jrok but maybe I’m wrong.
Also, does anyone knows if someone is working on reproducing those custom keys? I would prefer that rather than using hacked code like I do now. The dream would be a generic chip with all keys is one, like the atari slapstick reproduction that has been done.
Anyway, it was a really interesting project and I learned a lot of things. I don’t know if I’m going to sell it, it’s not a real multi and requires a bit of understanding of how to concatenate and program roms… but I’ll see. Do not hesitate to leave a comment/question if you have
For info I’m not a pro in electronics, it took me a while to do it and there might be better ways to do it. My main concern in this project was to not harm the board in any way. No solder, no cut trace or whatever.
At the beginning I just wanted to put some ZIF sockets on every socket to swap game quickly. But the roms are so close to each other than it's seemed not to be a good idea.
I searched a bit more and realized that a lot of roms share the same data bus and address bus, which means that I can put the code into a single bigger rom and spare a lot space! I just needed to take the Chip Enable signal of every rom and redo the addressing with TTL. Here is my first test done with proto boards on the OBJ bus.
It’s quite a mess but it works !
I did all of the 6 adapters and here is the full prototype done :
To change game I just need to swap the six roms, easy and quick!
But I had some issues on the program bus, and I realized after that photo that it was because of the inverted A16 on the PRG 7 rom. I had to add an extra TTL to deal with it (like for the VOI 0). I redid the PRG adapter and learned how to use kicad to print my first small PCB! Of course I did a mistake
I put the wrong hole size so I couldn’t put a ZIF in it. But anyway it worked well with a regular socket.
After that last modification I was able to do serious tests. I only own a Splatter house and a Dangerous Seed, so I used the decrypted roms done by jrock to test my work with the maximum games as possible. And the results were excellent: all 12 decrypted games worked perfectly, as well as Splatter House and Dangerous Seed using the original code and their custom key. Youkai Douchuuki worked also great as it doesn’t require any key.
From here I decided to design some cleaner PCBs and here is the final result:
I will probably do a last adapter to have the custom on ZIF socket too. It’s way beyond my first expectation and is totally enough for my personal usage, so I won’t go any further. A real multi won’t be hard to do for an experienced guy, that’s for sure. There is still the problem of non-decrypted games, to my knowledge only 12 has been done by jrok but maybe I’m wrong.
Also, does anyone knows if someone is working on reproducing those custom keys? I would prefer that rather than using hacked code like I do now. The dream would be a generic chip with all keys is one, like the atari slapstick reproduction that has been done.
Anyway, it was a really interesting project and I learned a lot of things. I don’t know if I’m going to sell it, it’s not a real multi and requires a bit of understanding of how to concatenate and program roms… but I’ll see. Do not hesitate to leave a comment/question if you have
