NES2NSF Help

Using FCEU and other versions such as FCEUX can tell you what the mapper of the game is, using a NES header header can also tell you, also a hex editor. The reason why you want to know what the mapper is so that you can know what the bank size select that is loaded into memory. For example, MMC1 or mapper 1 uses 16K sized banks. MMC3 uses 8K banks. You can also pick apart a ROM and section it off into banks if you need to. Also, examining the code to see how and where the banks are loaded by number according to the mapper.

(Edited from MMC4 to MMC3. MMC4 also uses 8KB banks as tepples stated)

I'll try to break this down into a few steps for you. It's by no means a definitive list. Also, you'll need to figure out your own way for ripping like we have.

1.) Find out the mapper controller of the game and banksize select.

2.) Use an emulator such as FCEUXDSP (Use UGETAB's version for additional NSF features).

3.) In the debugger, set a write breakpoint for the sound registers $4000 - $4004. This will tell you where the bulk of the sound code is. Keep hitting run to see where the snaps are.

4.) Right after a sound write, set a read breakpoint $8000 - $FFF9. Hit this a couple of times. This is to locate your sequence data. Make sure you have the right area in memory.

5.) Make sure you take note of these and write them down on Notepad or something.

6.) For example, a lot of Capcom games will have their code in the $8000 - $9000 range. The data in the $8000 - $BFFF range.

7.)Use FCEU MOD to dump the memory area, $8000 - $FFFF. This is only a base for testing. Prepend a NSF header on it and set the addressses on it. This is not your final product. This is just to get a working beta.

8.) Find your play address by setting writes to $4000 - $4004 once again. Find the NMI address by looking at the vector table in $FFFA - $FFFF range, look at all the interrupts here.

9.) Look for a call that jumps to the sound code area. JSR $xxxx for example. This is usually the easiest to find and is almost always in the NMI code. Sometimes the play call is in the IRQ, or completely outside of the NMI. You'll have to track them down.

10.) Set the play address in the header once you think you've found it. Examine the play code as well.

11.) Now, for the hardest part, that's tracking the init code. Reset the game and set a write breakpoint for $4015. Keep track of areas that write to this register and write them down. You can have anywhere from 1-5 or more areas that write to this register, or only in the play code. If you examined the play code, you should be able to deduce where the init entry is located at. Once you have figured it out, you'll have to write some code and set the header accordingly.

12.) Reset the game and set a write for $4017. Note what is written to this register. Set and reset the write breakpoint during times of the tune playing. Usually you'll want to use the first write. LDA $80 STA $4017 is often common. Use what's in the game. Sometimes a game doesn't write at all, which is rare.

Once again, read the docs that are out there. I can't really guide you step by step on this. This is the basic methods and I'm sure that others can expand on it. You need to somehow get a grasp on it and put the extra effort in there.

If you don't get a rip, don't let that discourage you. The list is growing thin as the harder ones are left. Some of them would be too difficult for a begginner to rip, unless you learn fast.