Make sure you are not using a Hack\Different Version\or another Region. Game Genie Codes only work on the Good (U) Rom Versions and Pro Action Replay Codes work on all Regions provided it states what region the codes are for.
A Game Genie Cheat Code is used by the Game Genie Cheat Device for the NES Console. The codes are encrypted and have to be loaded into the game for the code to take effect as they Modify the ROM not the memory.
So when you see a [Game Genie] Symbol in the Cheat Dialog Note Section you know that means its a Game Genie Code that needs to be enabled either before the game is loaded or the game reset (F1) after it is enabled.
A Pro Action Replay Cheat Code is used by the Pro Action Replay Cheat Device for the NES Console. The codes are in Hex which allow the codes to take effect immediately as they modify the Memory not the ROM, so they don't need to be injected into the game before the game is loaded or reset like the Game Genie Codes do.
So when you see a [Pro-Action-Replay] Symbol in the Cheat Dialog Note Section you know that means its a Pro Action Replay Code can just be enabled and used right away, not like the Game Genie that has to be enabled either before the game is loaded or the game reset (F1) after it is enabled.
Yes you can. more to the point you can add multiple codes to one cheat.
You can add the following Game Genie Formats in Jnes for Multiple codes.
Example 1: xxxxxxxx Or Example 1a: xxxxxx
Example 2: xxxxxxxx-xxxxxxxx
Example 3: xxxxxxxx-xxxxxxxx-xxxxxxxx
It is also possible to add to following code structures
Example 4: xxxxxx-xxxxxxxx-xxxxxx
Example 5: xxxxxxxx-xxxxxx-xxxxxxxx
Example 6: xxxxxx-xxxxxx-xxxxxx
You can also use and add PAR (Pro Action Replay) Extensions for cheats allowing you Options to choose from via the Pro Action Replay Codes with the => Symbol.
To add an Extension you would use the Address as Normal xxxx and make the Value an Extension by doing a ?? for the value making the Code: xxxx-??
Then in the Options box you would write the Choice of extension Options like:
as displayed in the above image.
128 Characters on both Game Genie and Pro Action Replay.
500 Characters but to be honest its always best to keep them short and to the point.
3 Codes comprising of 8 Characters and 2 dashed lines.
You can add 6 Codes per cheat comprising of 4 Numbers a dash line 2 Numbers.
But remember is you are going to use an Extension you can only use one code.
2,000 Characters although you will have a tough time filling that..
You can find a list by clicking Supported
You can find a list of links by clicking Cheat Sites.
Click on the Adding Cheats link for a full explanation.
Yes Jnes will allow you to add, edit & delete through the GUI. Click the following for more information on Adding, Editing, Deleting & Using Cheats
14. How do i use cheat codes in Jnes ?
For a full Visual Explanation click on the Using Cheats link.