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I followed the directions for TKROM > TNROM conversion, and I used an early run Mario 2 cart. The game runs, but the graphics are heavily scrambled. Even weirder, the game has to be reset before it works at all- I get a completely blank screen otherwise. I cut the necessary traces as per the instructions, and I verified that the traces were cut using a multimeter. I've also checked my wiring twice.

Any clue as to what's going wrong here?

I've made a number of devcarts including TLROM, TKROM and TSROM. I have found that most MMC3 games will work on any MMC3 cart except that games with RAM need the TKROM board and those with CHR-RAM need TGROM. Whenver I had trouble I checked the connection of each pin of the EPROM to wherever it was supposed to connect to on the edge connector or MMC3 chip. Try using a light touch on the multimeter leads as sometimes the solder doesn't wet the EPROM socket pin and you get an intermittent connection. This can cause some odd behaviour such as pressure on a solder joint making the connection momentarily. Also make sure the various leads of the EPROM such as PRG are connected to Vcc or ground as the data sheet suggests. You may try a different dump too as I have found many ROM's which work on emulators but not on the NES perhaps because of op-codes which are invalid.

If you put FF3 on a TSROM based cart, you added the battery youreslef, right ? Be sure you didn't do anything wrong there. If you didn't had battery, the game will perfectly runs, but when you shut the power off, all saves will be lost. I doubt you could beat the game without turning the power off once (you will still be able to save, in case of if you get game over).

If the graphics are wrong, you probably did something wrong with CHRRAM. I think you had to glue a pad, and that should be hard to get good contact without short-circuit other pads. You may also did some stupid error on wiring the chip, like cutting the track one pin early or late, leaving it floating or place a wire one pin early or late, causing signal conflicts.

its VERY easy, i make my FF3e on Super Mario Bros 2/3/Gauntlet 2 cart.
you need ONLY modifi CHROM to VRAM. And Connect BATTERY to WRAM.
http://nintendoallstars.w.interia.pl/romlab/nesvram.htm

SDM: That link you posted for the VRAM 8/64kb pinout conflicts with another wiring diagram on the same site http://nintendoallstars.w.interia.pl/ro ... m2cram.htm

It seems the chr /RD and /A13 are flipped around. Which one is correct? Also where would you go abouts getting the propper vram chip? From other NES carts, or is there a specific part number you can buy?

You can use any 6264 chip, different manufacturers will have a different part number but any "64K x 8" SRAM will be the same.

A 62256 chip would be ok too (256kbit x 8). Just wire the extra 2 address lines to VCC or GND. I can ship you one for $5 if you want.

I assume any of the 62 sram series would work with this as long as you dont leave the extra data lines floating?

Never leave any floating data lines. EVER!

Also.. SRAMs tend to be very picky. Spend the $$ and get good ones. Trust me on this one.

Well, you probably meant address lines, right?

Ya, I ment address lines. Sorry about that.

Yep, same thing applies to address lines. Or any pin whatsoever on CMOS chips, never leave any floating. Unless it says 'NC' (not connected internally) on the datasheet.

uh... good post for what i'm going to be doing, making FF3 from an early SMB2 (all 72 pins). but since i'm a little confused on what i need, could you tell me which one of those 2 links to follow, and which chips i should buy? (i'm new to this, about to buy my eprom programmer in the next day or two)

I've given up on this one for now. I think I messed up something important when I was cutting the traces, so I'm just going to toss the board I have and wait an eternity to find another TSROM-01 version of Mario 2. (Were there ANY other games that used this early version of the board?) Next time I try this, it'll be done entirely through lifted pins because I hate having to cut traces.

At least I didn't actually kill a copy of Mario 2 for this, as I moved the mask ROMs over to a TSROM-04 board salvaged from Home Alone.

You can fix any board with just a bit of wire and solder if you take your time and don't give up. Post some pictures of the mess if you want any help.