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[NES] TMNT 1: Question about background coordinates

Started by retro_hun, March 10, 2023, 04:11:25 AM

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In the very first NES TMNT game, when you pause the game, there is this text saying "AREA 1", or "AREA 2". I'd like to change this to "1.FEJEZET" or "2.FEJEZET" (1st CHAPTER or 2nd CHAPTER in english). I can edit the text with no problem, but the number is not defined. I thought it's because it behaves like a sprite, but no. It's not an object, it's a background element, and it has its values written into PPU. I had success in changing an object's xy coordinates in other games, but how can I change a backgrounds X position that behaves like a variable?

I had some experience and success dealing with other problems using the debugger, so I tried to trace back the value "01" (it is the number "1") but usually hit a wall, when I arrive at CPU mem $22, where I can see the values "03" and "21", corresponding to the 3rd row and 21st column, where the number gets written on the screen, but thats it. Also tried to examine the PPU ports $2006 and $2007, with no avail. Is there a solution for this?

Greeting from Hungary
- RETRO_hun


Oh, wow! This is going in to my tutorial folder. Thank you :)