I've been looking at the PC Engine version of Parasol Stars and I'm trying to put together a hack to make it act like an arcade game.
The game already has "credits" but no insert coin function.
I'd like to add some code so that pressing the select button increases the number of credits by one.
I'll also need to change the text to say "Press P1 Start" or similar.
So far I've found some memory locations:
F0C6 - Number of credits when game starts
F0F9 - Number of lives when game starts
3D00 - Number of credits during game.
2453 / 2448 change to different values when buttons are pressed on the controller, the left digit seems to represent the direction pad and the right one the buttons.
I'm fairly new to ROM hacking and have mainly programmed in C.
Am I right in assuming that I need to :
Find the code that reads the button presses.
Redirect the code to a different bit of memory
In that memory, have the code to increment the credits
Redirect back to the previous code location.
I've worked in assembler before, but not for a long time, I guess I will need to look up the PC Engine instruction set.
Can anyone recommend a good debugger for PCE roms?