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Author Topic: Modifying text that's 8*16  (Read 1234 times)

headframe

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Modifying text that's 8*16
« on: June 14, 2020, 08:55:26 am »
I am currently having my first try at rom hacking a NES game and have an issue trying to modify text in a specific menu. I sincerely hope this isn't a really stupid question.

I have modified the text in the hex editor for the parts required but this particular menu has the text over two 8*8 tiles, re-using these tiles on different parts of the screen (as in top half of A and bottom half of A). As I understand it they obviously aren't a single address as they are two tiles that are re-using common tiles to display text? Does the hex code of the rom store what tile is displayed at x/y location on backgrounds? I have played around with a debugger trying to figure that out but have gotten nowhere.

If anyone could point me in the right direction for some info or some other resources i can look into how I go about this it would be greatly appreciated.

Cyneprepou4uk

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Re: Modifying text that's 8*16
« Reply #1 on: June 14, 2020, 09:53:09 am »
If these letters are drawn with background tiles, their position is set in a nametable, probably in the first one
https://wiki.nesdev.com/w/index.php/PPU_nametables

Open fceux - hex editor - view - ppu memory, try changing bytes manually starting from $2000 to understand how it works

Data in the nametable is already unpacked. Code reads data (which is most likely compressed) from rom, and writes it into ppu memory via $2007 register. You can set write breakpoints to the nametable to find out where these values are taken from
iromhacker.ru - NES ROM hacking tutorials for beginners. Please use Google Translate browser extension

headframe

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Re: Modifying text that's 8*16
« Reply #2 on: June 14, 2020, 10:05:02 am »
Thanks for your help. Am just scratching around with this and had the name table editor which showed the x/y position, PPU address and tile ID. I found that in the hex editor but it didn't change so I will play around with it a lot more thoroughly now i think I'm on the right track. Thanks again for your help  :thumbsup: