First, you'll need some codes for the game you're playing. You can get Game Genie codes here
, and it shouldn't be too hard to find Pro Action codes if you search the web a bit.
Now let's say I want to cheat in... Blaster Master. I look up the game on the Game Genie site and see a list of codes for it. The "infinite lives" code would be really useful, so I'll use that. The code is SZUGYIVG.
Now I start Nestopia and go to Options --> Cheats. The cheat window will open up. It has two big white boxes to put codes in, one labeled "static codes" and the other labeled "temporary codes." All the codes you enter in the "temporary codes" box are always automatically deleted whenever you close Nestopia, while the ones in the "static codes" box are saved and will still be there next time you play. I only want to try out this infinite lives code, so I'll put it in the "temporary codes" box by clicking on the "add" button underneath it.
The "add code" box will pop up. There's a lot of stuff here, but I'm just interested in entering a Game Genie or Pro Action code. To do that I'll click the button next to "Game Genie" or "Pro Action (Game Genie in this case) and enter the code SZUGYIVG in the text box directly underneath. There's also a textbox near the bottom that let's you enter a description for the code if you want to. I'll type in Blaster Master - Infinite Lives
, then click "submit."
The infinite lives code will be added and appear in the "temporary codes" box. I could add in more codes if I wanted to, but infinite lives is all I'm interested in for now. I click "OK" to close the cheat menu and then load the Blaster Master ROM, and SHAZAM, I have infinite lives.
Those are the basics, but there are a few other things you may want to know. There's a checkbox next to every code. You can uncheck it to turn that code off. If you wanted to turn the code back on, of course you'd check the box again. Remember to turn off codes when you start a different game; if you started Contra with that Blaster Master code turned on, the game would probably have some glitches.
There are a few buttons besides "add" underneath the "static codes" and "temporary codes" boxes. "Delete" will delete any codes in the box that you've highlighted. "Clear" will delete all the codes in the box. "Export" will let you save all the codes in the box in an .nsp file, and "import" will let you load an .nsp file you made.
Wll, that's everyting except creating your own codes byte-by-byte. I hope I made sense.