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Hi,

I'm in the process of creating a CNROM devcart and am having some troubles with the Panesian games. The games boot up fine, but all of the graphics are garbled except for some of the text. Now, the issue is that CNROM's only support up to 32K of CHR-ROM, but the Panesian games all use 64K of CHR-ROM.

However, I know that a few people have successfully made carts that run these games. Is there a way to modify the CHR data to fit into 32K? Because if you check out this photo, it appears that a 27C256 chip is being used for the CHR-ROM:



Here is some proof people have got them working:
http://www.gamegavel.com/Nes-Nintendo-3 ... on_details

http://nesdev.com/bbs/viewtopic.php?p=7 ... 8edb2#7760

Now, I tried to contact the poster but they haven't been active since about 2005, so it seems like I might not get an answer.

Any help anybody could give would be appreciated!

Thanks,
-B

You could take out CHR banks that obviously don't have game graphics in them, and then rewrite the program to skip cut scenes that use those banks. The version of Tengen's Tetяis (CNROM) on 100-in-1 Contra Function 16 had similar treatment done to reduce it to NROM size. I don't have the BBB rom in front of me right now, so I can't look at it to tell you which CHR banks are and are not used for gameplay.

My guess would be that Nintendo CNROM carts are wired for 32K CHR maximum, where the cartridge used for the CNROM variant actually can have higher page numbers and thus more CHR-ROM. Maybe you need to replace some of the logic chips or rewire something, I don't know.

Most likely you just need to connect the 74161's Q2 output to CHR ROM's A15. If that doesn't work, then you may have bus conflicts which can be resolved in software or hardware.

I know I have read how to do this, I'm not sure where maybe Nintendoage. But I do recall it to be something along the lines of whats posted by kyuusaku.

You need to place '161 Q2 output to CHR A15 AND to wire CPU D2 to '161 D2 input (after aving cut it from VCC where it should normally be tied (or D4 on older carts with diodes)).

Bregalad wrote:You need to place '161 Q2 output to CHR A15 AND to wire CPU D2 to '161 D2 input (after aving cut it from VCC where it should normally be tied (or D4 on older carts with diodes)).

What would be the equal to this if using a 27c020 for the CHR please? I ask as I have alot of 27c256 chips, lots of 27c020 but no 27c512's.

Heck even just a picture of how it's wired using a 27c512 would be fine and I can just figure out the differences in the eprom pinouts myself.

What the hell is the point of a Panesian game without the non-game graphics?

Dwedit wrote:What the hell is the point of a Panesian game without the non-game graphics?

There's as much point to taking the babes out of Bubble Bath Babes as there is to taking the strippers out of Strip Tetris: some people actually like the game itself. There was enough of a point for AVE to put swimtails on the Babes and sell the result.

Bregalad wrote:You need to place '161 Q2 output to CHR A15 AND to wire CPU D2 to '161 D2 input (after aving cut it from VCC where it should normally be tied (or D4 on older carts with diodes)).

Where is CPU D2 located? Also can you check this pic out for me and let me know if I got the right idea so far? I think I got this down aside from where to find CPU D2

Please help me locate CPU D2?

It's pin #47 on the connector.

Bregalad wrote:It's pin #47 on the connector.

Thanks!

Bregalad wrote:It's pin #47 on the connector.

CPU D2 (pin47 on the edge connector) is also attached to PRG D2 ( PRG pin 13). Does this connection need to stay attached also or should the trace be cut? (pictured below)

nintendo2600 wrote:CPU D2 (pin47 on the edge connector) is also attached to PRG D2 ( PRG pin 13). Does this connection need to stay attached also or should the trace be cut?

It stays, don't cut it.