However I assume something else is wrong if you couldn't get it to work with rainwarrior's export guide. I find it strange that you get different results with 32kB and 64kB files. If your cart is 32kB then the proper way is to connect the last address pin of the EPROM to ground, have you done that? The PRG export option should be perfectly compatible with NROM and CNROM.
I haven't done any rewiring of the EPROM pins. I was pretty sure that EPROMs I'm using (M27C512) were compatible with the PRG pinout without rewiring, so it wouldn't be necessary.
Since I've verified the PRG you made was actually fine, you might try posting your problem at nesdev with pictures of your board and a description of what you've done.
Seems to be pretty similar to my situation. Mine's a NROM-128 not a NROM-256, but that shouldn't affect it once the EPROMs are in there I wouldn't think.
To be honest, I'm kind of not surprised at anything being the cause at this point.
There isn't any chance that what's on the CHR chip would negatively effect it, would it? I'd think not, since I've tried a Duck Hunt PRG in the Baseball PRG slot. I've gotten whacky, insane garbled gibberish doing that (since the graphics data obviously doesn't correspond), but the game doesn't crash or anything.
One thing I just realized is that NROM-128 is for 16kb PRGs. This isn't going to work for this situation, because the high address bit isn't wired to the ROM. Sorry, I should have noticed this earlier; I forgot that a lot of early NROMs only used half the available space.
You can fix this by connecting A14 on the chip to the A14 pin on the board. There's a guide at chipmusic.org.
Aha! Well that certainly explains a lot, especially in term of how the dumps worked but the new data didn't.
Truth is that some of my stock-piled NROM carts are NROM-256s, so I might just try putting a socket in one of those.
If that doesn't work for any insane reason, I'll try doing the NROM-128 rewiring. I'd rather not have the dangling wires near the cart socket if at all possible, but if worse comes to worse...
On a semi-related note, would you happen to know if the corresponding Famicom versions of the NROM-256 games are compatible with EPROMs in the same way that the NES carts are? What about PAL carts?
No idea. Maybe try looking it up on the nesdev wiki, or ask at the nesdev forums.
I would expect PAL to be similar to NTSC (PAL can use the same boards just fine).
Famicom I don't know; on the NES all the boards were made by Nintendo, but on the Famicom distributors could make their own boards. It's likely that NROM boards for Famicom will be very similar to NROM boards for NES, but I don't really know.
I have a possible hunch about the Famicom boards, since I have a copy of Hogan's Alley that has the Famicom board in a converter (lucked out with that I know). The strange thing is that (last I checked) the PRG looked the same but the CHR chip looked like it was 24 pins rather than 28.
I kinda figured that the PAL boards were basically just like NTSC boards but with the PAL CIC chip. Is this essentially the case? Makes sense if (from what I've heard) PAL runs on an American top loader no problem (since it neither has the lock CIC in it nor checks the key CIC on carts).
PAL and NTSC boards should be the same, yes. PAL games are built for different timing, so there can be any number of problems trying to run them on an NTSC NES, but aside from the CIC you could take an NTSC game ROM, put it on a PAL board, and it should work fine on an NTSC NES.
Success! The EPROM works on the NROM-256 board. I gotta say I'm super stoked with finally hearing MY music on the hardware. Thanks so much for your help, rainwarrior and jsr.
I had to double it to fill up the chip, but the cart works nonetheless.
