The japaneese version of the NES game Contra (Kontora), unlike the more common U.S version, has some nice cutscenes between stages, at the begining and at the end that have been removed.
Even worse, the european version, named Probotector, have robots instead of human fighters.
How is it possible to play the original game without buying the original rare, in japaneese and expensive cart that needs an adapter nor playing it trough an emulator ?
- Knownledge in electronics, soldering and EPROM programming. If you don't have that, never mind, play it trough an emulator.
- A donator cartridge. The cartridge will be destroyed, and Contra will be on it instead, so worse is the original, the more you'll benefit from the change.
Don't destroy a rare game !! The board must be TLROM (or compatible), see below for more information
- 2x27C1001 (or equivalent) EPROMS, or 128kBx8
- Some tiny isolated wire (wirewrap wire is fine, the best it copper wire with an isolation that is automatically removed when heat is applied).
- EPROM programmer
TLROM is one of the most common NES boards, and found it should be pretty easy, lots of games, including lot of bad ones, uses it.
Note that the original Contra game was using a Konami VRC2 mapper, I hacked the game to run fine with a MMC3 mapper.
The translation was done by someone else, and they changed the title to "Gryzor", the european arcade version's name, for unknown reasons.
TLROM games that comes in my mind are Batman, Megaman 3, Megaman 5, Tiny Toon Adventures, Tiny Toon Adventures 2, Ninja Gaiden 2, Ninja Gaiden 3, and there is a lot others much worse, remember to destroy a game as common and as bad as possible.
To be sure to know which games uses TLROM boards, use that doccument. Note that there is probably a lot of Famicom games not included in that list, if you want a Famicom donor card (whici is unlikely to be the case).
- Download either contra_prg_ntsc.bin or contra_prg_pal.bin (in function of if you have a NTSC or PAL system) and burn it on the first EPROM
- Download contra_chr.bin and burn it on the second EPROM. Find some way to mark your EPROM with a post-it or something, you mustn't mix them up !
- To open your cartridge, use the tool you can found, I personally use a mini-fork that I randomly found, it has the exact size of a NES scew, and act like a scewdriver.
- Disolder both old PRG and CHR chips (for newbies it's written on the board wich chips are PRG and CHR roms). Make sure to not damage the board, but you can damage the old chips as much as you want to.
- Cut tracks leading to pins 2 and 24 of PRG ROM.
- Cut tracks leading to pins 2, 22, 24 and 31 of CHR ROM (and be carefull to cut the GOOD tracks, I've mistaken and cut track 23 instead of 22, and that was a pain to fix).
- Be sure to know where you will found wires for old signals that has been cutted that needs to be rewired. That should be done BEFORE soldering the news rom, else you won't be able to see tracks on the top of the PCB !!
The best is to solder the wires on vias (holes that goes through the board), but if you cannot find any, scratch the PCB with any tool to have the copper directly available, then solder your wire on the copper.
- PRG rewiring :
- Solder the new PRG chip where the old was, and the new CHR chip where the old was (if the connector is down, then CHR is on the left, and PRG on the right).
- Check that you did everything right and proprely at least two times.
- Make sure that the conectors are clean enough to have the cart working, else clean them with some solvant against colophane/oxydation.
- Close the cart carefully
- Play it on your NES as you wish ;-p