Building a Marvelous “development” cartridge


Most people have probably never heard of Marvelous. It’s an obscure Super Famicom game that was released only in Japan in 1996. It was also Eiji Aonuma’s first game. (He’s the man who is responsible for all of the major Zelda titles since Majora’s Mask.)  There’s a great article over on Hardcore Gaming 101 about the game, and a developer interview on I highly recommend you read them. (URL at the bottom.)

Unfortunately, being in Japanese, the game is impossible to understand if you can’t read the language. And while many Japan-only releases get English fan-translations, Marvelous remained untranslated until very recently. A man by the name of “Tashi” posted an incomplete translation on on December 14, 2012.

In terms of quality, the translation is very basic at best. Tashi only translated the in-game text and a few interface graphics. It retains and uses the game’s built in English font, which uses equal-spaced characters. Close up graphics of signs and other things that have written text have not been translated, but it shouldn’t hinder your ability to play through the game.


A screenshot of the translation. Notice the very “Japanese-style” English font. “Team work” and “Item” icons have been translated.

Since the translation is incomplete, I am going to build a “development” cartridge that will have a ROM socket attached to the outside of the cartridge shell. This way, if/when the translation is updated, I can easily swap ROMs. Most reproduction cartridges involve bending and soldering directly to a ROM chip’s legs, making them a permanent affair.


A picture of the completed cartridge. A red DOOM shell was used to house the PCB because Japanese Super Famicom shells are rounded, making fitting the ROM socket impossible.

To build this cartridge, we need to start with a donor SA1 compatible cartridge. There are other SA1 games out there that can be used, but most do not have the correct amount of SRAM (static RAM) that Marvelous needs. Marvelous requires a whopping 512k of SRAM. (For comparison, Super Mario RPG, another SA1 game, uses 256k.)

Fortunately Marvelous typically sells for $20 complete in box on eBay. I bought a loose cart for $20 from an American seller. Most cartridges will come from Japan.

The other thing you will need is a US SNES shell to house the cartridge in. Japanese Super Famicom and European SNES shells are rounded, so you can’t sit a ROM socket flat against the shell. Also note that the shell needs to be from a “special chip” game that has the extended cartridge pins. I am using a DOOM shell. The DOOM PCB is going to be a donor for a SuperFX repro project in the future.

So now we’re ready to make this thing. Line up the 42-pin IC socket on the back side of the shell and mark off where the pins are. Take a tiny drill bit and drill out 42 holes for the pins to sit in. Once this is done, fit the socket in place and use some hot glue to secure it. Remember this is a development cartridge, it’s not supposed to look pretty.

So now we need to take our Marvelous PCB and remove the original ROM. Since we are never going to put the original chip back on, we can destroy it. I used an Exacto knife to carefully cut the pins off the chip. Once one side of pins are removed, bend the chip back and forth to break off the legs on the other side. Now use a soldering iron to clean up the solder pads on the PCB. Be careful though, they are extremely fragile. I managed to remove a PCB trace and had to find another spot on the PCB to solder to.


Super Mario RPG board with the ROM removed. (Credit: kogami from Pixels Pirates forum)

Now we carefully need to run wires from the IC socket on the shell to the solder pads where the old ROM was. The wires almost line up perfectly, with the exception on one small wire. The 44-pin MASKROM pinout uses pin 33 as a swap byte function (not used), and moves A20 to pin 44. Pin 33 on the EPROM is A20, so we need to run that wire to pin 44 on the PCB. Note that the pin numbering on the EPROM is 1 off from the MASKROM layout. So for example pin-1 on the EPROM goes to pin-2 on the PCB, etc. I like to start from the bottom at pin 22 and work my way up. FYI I got my wires from an old rounded IDE cable. I recommend using multiple colors so you don’t accidentally get your wires mixed up.


Diagram showing how to wire the 27c322 EPROM to the 44-pin MASKROM layout. Note that pin-1 and pin-33 on the PCB has no connection.

Start with wiring the inner pins, (2 to 22) and then do the outer pins (23-44). When you are finished you should have something like this:


Notice I used scotch tape to hold the PCB in place to the shell while I was soldering.

Once you are complete, carefully put the EPROM in the socket and test the cartridge before closing it up for good. You should never have to open this cartridge again unless the battery dies. (Now would probably be a good time to put in a fresh battery!)

So you might be asking, why sack an original cartridge to do this when I can play this on a flash cart, such as the Super Everdrive or the SD2SNES? Unfortunately, you can’t. Marvelous uses an add-on enhancement chip called the SA1. It’s a pretty advanced processor that is actually equal in power to the SNES’s main processor! Flash carts cannot emulate this chip right now (and possibly never, unless a new design is made).



One thought on “Building a Marvelous “development” cartridge

  1. One of my favorite games for the Super Famicom. It’s such a solid, fun game. I hope you enjoy it. I still need to play those two Satellaview games. That might be a near future project.


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