Hey guys, want to ask about NES repro

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rigohoward
Posts: 2
Joined: Thu Jan 15, 2015 11:32 am

Hey guys, want to ask about NES repro

Post by rigohoward »

Well i'm new as user here, i been reading from long time ago but this time i want to interact directly :)


First of all i want to say this community is one of the greatest for all the interesting help and guidance published... So i wan to thank all the users for sharing all their knowledge!


Well me and a friend currently got a few famicom carts from ebay through exciting bids :p... Sadly we have a couple of repeated carts and we want to transform those games into new obes using the millenary reproduction thechnique ;)

Sooo... Here is the deal. We have an EPROM programmer UV Eraser and 27cXXX IC's

Our first try was made using a NROM (mapper 0 right?) and 27c512 EPROM... The donor cart was an Spartan X cart and we try to do a SMB reproduction, Pac Land Reproduction and even an Spartan X reproduction (test purposes)


So as 27c512 has 64kb of capacity, we duplicate de prg file to match the size (before doing the header cleaning and split of the nes rom) we burn the bin file and this were the results:

Strike one Pac land: the game boots, you see a lot of garbage but actually you can play the game and heard all the musisc and sfx
Strike two SMB: the same as above
Strike three Spartan X: thw game boots fine, music and graphics are perfect

So the question is, i have to burn both, prg and chr to the 27c512?, probably this is a noob question for all the experimented reproduction gurus, but this is our first try and we can figure out what we miss yet :p


Thanks for your attention!
FrankWDoom
Posts: 260
Joined: Mon Jan 23, 2012 11:27 pm

Re: Hey guys, want to ask about NES repro

Post by FrankWDoom »

Did you leave the Spartan X chr mask rom on the board? For NROM you have to replace both chips. Program another chip with the chr data and swap that in for the mask rom.

I don't know what you're using to split your files, but I wrote this to make it as simple as possible: famiROM
rigohoward
Posts: 2
Joined: Thu Jan 15, 2015 11:32 am

Re: Hey guys, want to ask about NES repro

Post by rigohoward »

Thanks for your kind response, it solves the mistery:)

Good tip about FamiRom!

We were working with some NROM and CNROM,for now and then will we try with UNROM cart
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MaarioS
Posts: 149
Joined: Wed Jul 22, 2009 8:53 am

Re: Hey guys, want to ask about NES repro

Post by MaarioS »

In case of UNROM I bet this is the easier choice for you to testing purposes since it uses PRG ROM + CHR RAM (SRAM) chip so the graphics data is transferred from PRG ROM to CHR RAM. This means you need to only replace the PRG chip and that's it, the game should work fine. In case you modify NROM or CNROM board which use PRG ROM + CHR ROM, you have to replace both chips. Otherwise the graphics will be glitchy
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