Convert Nrom games to fds.

[Gamester]

Can anyone tell me how to do that. i read in the forum that it should be possible.
But i dont get it working.
Every time i swap the prg and chr files of a .fds image with a Nrom prg and chr the disk boot but nothig happens.
Can some explain me ?

[natt]

An nrom game expects to have full control of 8000:ffff, where as FDS has prg ram at 6000:dfff and a fixed FDS bios at e000:ffff. Besides the relocation, this means that you don't control the vectors directly. (You can have the bios hand off to your vectors, but this requires a particular ram write).

Converting an NROM game to an FDS image is going to require code modification in general.

[tepples]

Code modification for the FDS's different runtime environment is part of why the minus world in SMB1 (FDS) isn't the same as the cartridge version's repeating 7-2; it's actually beatable in under two minutes.

[MottZilla]

Besides needing to disassemble and reassemble the entire program ROM to move it from $8000-$FFFF to $6000-$DFFF you'll need to make some modifications as the FDS BIOS expects certain ram locations to contain certain values. Shouldn't be a big deal compared to fully disasm and reassembling the program rom.

[Gilbert]

There are also some information in this thread. I think these two threads can be merged.