How to Make a SNES Reproduction Cartridge

Using my custom SNES PCBs to make your games? A quick guide has been generated for your viewing pleasure!

Disclaimer: This is a somewhat involved process that involves a decent amount of soldering and possible desoldering, and using a lot of older technology. You might run into issues with broken parts, and it might get frustrating! I’m not responsible for any damage to you or your games. That being said, I’ll certainly try to help you out in any way I can. I’ve run into a large array of problems in the past, so I should be able to give you valuable input in solving your issue!

I’ve taken a lot of time to go through and learn all I can about how SNES games work, and I tried my hardest to make the most comprehensive and easy-to-follow guide so that you can do it yourself! That’s right – custom-made SNES cartridges. This even includes ROM hacks, and foreign games never released in your region all on your very own SNES system in your living room for cheap! Luckily, SNES games aren’t actually too complicated to make (way easier than NES games), and there are a ton of different ways you can make them. Despite the daunting length of this tutorial, once you make a game once or twice, you get pretty efficient at it. It only takes me 10 minutes or so to make a game using my own SNES PCBs at this point, and I don’t even have to reference this guide anymore. So as long as you have a bit of soldering experience, you can put nearly any SNES game you want on a cartridge!

Table of Contents

Step 1: Gather information on your game
Step 2: Determine the method of reproduction
Step 3: Choose your board
– Donor cartridge
– Custom PCB
Step 4: Determine which memory chips to use
Step 5: Expand your ROM and fix the checksum
Step 6: Finalize files for programming
– 27C801
– 27C160
– 27C322
– 29F033
Step 7: Burn your ROM
– 27C801
– 27C160
– 27C322
– 29F033
Step 8: Double check your chips, and prepare the donor board
Step 9: Install chips on the board
– 27C801 (donor)
– 27C160 (donor)
– 27C322 (donor)
– 29F033 (donor)
– ExHiROM (donor)
– Custom PCB
Step 10: Finish your game

Equipment you will need

You’ll need a few basic things:

1) Programmer. This is what you use to program the chips the game data is stored on. I got mine on eBay for about $50. It’s a TL866 MiniPro programmer. There’s an updated model, the TL866II, and this one seems to work just as well. This programmer has worked flawlessly for me so far, even after 5 years, and it’s pretty easy to use. This is the same one I used for the NES tutorial. There are other more advanced programmers out there, but they run a lot more expensive. If you have one of these, you’ll have to figure out how to program the chips yourself (though, if you’re reading this and you already own a programmer, you probably know what you’re doing).

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Cost: ~ $50

2) A board. You can use either an existing game that you’ll dismantle, or a custom board. Your game will determine which method is easiest, and which you can even use. I provide custom boards on my store page if you’re interested in supporting the site!

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Cost: $5 to $15

3) EPROMs/EEPROMS (and programming adapters). Yes, that’s right, both EPROMs and EEPROMs can be used, and there is a difference! EPROMs are older technology (with a single ‘E’) and are erased via UV light. EEPROM on the other hand, with two ‘E’s, stands for “Electrically Erasable Programmable Read Only Memory.” The difference between the two is that EEPROMs are erased with electrical signals rather than UV light. Functionally they are nearly identical. Convenient!

In this tutorial, I will go over multiple methods of making games using 8 Mbit, 16 Mbit, and 32 Mbit through-hole EPROMs, and also using 32 Mbit surface mount EEPROMs.

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If you want to use anything except 8 Mbit EPROMs, and you’re using the MiniPro, you’ll need programming adapters so that you can program these chips. Other programmers like the GQ-4X, can handle all of these chips, but I’ve never seen that programmer go for less than $100 online. I make these adapters, and can sell them to you over on my store page, or you can make your own boards (I’ll provide schematics later). I’ll go over which one you might need for your project later on.

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Cost: $2 to $15

4) EPROM eraser. This is for prepping your EPROMs, and fixing your inevitable screw-ups. You do not need this if you plan on only using the 32 Mbit surface mount chips. Got it on eBay for $15 (can you tell I like eBay?). I use this more often than I’d like to admit. I’d recommend picking it up.

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Cost: $15

5) Miscellaneous hardware. You’ll need some wire (I prefer 28 gauge) if you’re using a donor cartridge, solder, and a soldering iron, at the very least. You’ll also need a special screwdriver for opening SNES games, as they use specific screws. You’re gonna want the 3.8mm “Security Bit” screwdriver. The 4.5mm is used for opening Nintendo consoles and Sega games. Might as well buy both though, they usually come in bundles from what I’ve seen online.

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So when all is said and done, you’re looking at an installation cost of $60 to $70, depending on what you have lying around, any adapters you need, and if you want to get the eraser. After that, each game you want to make will cost between $5 to $20, depending on which chips you select, and what board you choose.

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Step 1: Gather information on your game

The first step you should take is to find out the crucial information of your desired game. To do this, you’ll need to find and download the ROM file, or ROM hack patch file. I’m not going to tell you where to download these from – you’re smart enough to figure it out – but as I warned in my NES reproduction tutorial, avoid downloading anything except like, .zip or .7z files. Some websites will ask you to add an extension or download an executable – do NOT download these. You’ll have a chance of getting malware if you do.

Floating IPS

Before we get into the meaty part of the tutorial, we need to apply any necessary patches to your ROM. You most likely won’t have to do this step, especially if you’re making an unmodified game. I personally only had to do this once for a very specific ROM hack. But if you’re planning on making a translated version of a foreign ROM and the language patch isn’t already applied to the ROM, or you want to add some other patch to a ROM that’s not already part of your file, you’ll have to use a program called Floating IPS to patch it. It’s very simple to use.

Open the program up, and click on “Apply Patch”. The patch you download should have the extension .ips or .bps. Locate and select the patch you want. Then, it will prompt you to apply the patch to the correct ROM. Find the ROM file in your folder and select it. It will prompt you to save it under a new name. That’s it!

Run your ROM in an emulator

It’s important to run your ROM in an emulator to determine it’s the exact game you want to make. Sometimes, a ROM file you download will be corrupt, or if you had to patch the ROM the patch might be corrupted, or something else could have happened. So you should download an emulator to run the file in. Personally, I usually use snes9x, but you can use pretty much any emulator on this list to check the game out.

Just make sure that the game is the exact version that you want to use, and that it can run for a few minutes without freezing. This might seem silly to do, but there are plenty of mislabeled ROMs I’ve gotten throughout the years.

uCon64

Once you’ve verified that your ROM is correct, you’ll need to download the most important program we will use, called uCon64. This is a command line utility that will give you all the information you ever wanted to know about your ROM. Using it is a bit tricky, though, so I’ll go through exactly what you need to do here.

(I recommend making a folder where you can put all of your work materials to make it easier to navigate.)

Download and unzip uCon64. Now, open Command Prompt (hit the Windows Key and R at the same time, and type “cmd” and hit enter). Change the directory to the folder where uCon64 is located by using the cd command (it’s located on my D drive, shown below). If the cd command doesn’t work, try adding /d after it.

cd [path to folder]       OR       cd /d [path to folder]

Now, navigate to the place where your ROM is located (I will be using Final Fantasy 5 as an example). Hold the shift key and right click on the ROM, and click “Copy as path.” Now, go back to your Command Prompt screen and enter:

ucon64 [path to ROM]

Use CTRL+V to paste the path. Your screen should look like this:

cmd1

Now hit enter, and you’ll get a lot of information in front of you.

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Let’s take some time to go over what each of these categories are.

Bank Type

There are two main types of banks known as HiROM and LoROM. In the command window, HiROM games will display as “HiROM: Yes” and LoROM games will display as “HiROM: No”. Pretty self explanatory.

SRAM

Some games use SRAM, some do not. If yours uses SRAM, you should provide it with the exact amount it requires. The reason being is that some games check to see if the amount of SRAM available equals a certain amount. If it does not, like if you’re supplying it with a chip it wasn’t meant to be supplied with, the game will determine it to be a pirated copy and screw the game up! Keep this in mind for later.

Chips

This column lists any specialty chips the game uses. This doesn’t include the chips that are used on all games, like the CIC region chip or the Mask ROMS. For example, Star Fox 2 uses the Super FX chip. For better or worse, there are not that many games that fall into this category.

Another common thing that many games use are batteries. I’d recommend buying a handful of new batteries with battery holders if your game uses one, even if you’re converting an older cartridge to a different game. It’s been about 20 years since many of these games came out – their batteries are probably almost dead, if they aren’t already. I recommend getting the yellow ones that come pre-mounted. The original batteries are spot-welded to the holders so they don’t move – replacing just the batteries without removing the mountings is tricky and not worth the time.

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Region

Just make sure the ROM you’re looking for is the correct region (PAL or NTSC), otherwise, they won’t run well (or at all) on your SNES/Super Famicom (unless you modify your machine). Look up where you live and if it’s in the PAL region or the NTSC region if you’re unsure. Converting a game from one region to another is difficult, and it isn’t as easy as disabling the region lockout chip (CIC chip). Countries in the PAL region run on 50 Hz power, where countries in the NTSC region runs on 60 Hz power, and strangely enough, some games will run faster or skip frames if you use them in the wrong region.

ROM Size

This is how large your game is, obviously. The size only comes into play when you’re deciding which chips to use to program your game, because all cartridge boards are capable of handling pretty much any size game you can make.

Speed

This corresponds to the data access delay times of the ROM. You can pretty much ignore this, as most EPROMs and EEPROMs available anymore will be fast enough for both types of games. Make sure the datasheet of your chip specifies AT LEAST 120ns access time (120ns or less). I’ve never run into one that was slower than this though. If you’re curious about the differences between SlowROM and FastROM, check out my detailed write-up about the SNES cartridge inner workings.

Knowing all this, you should note the region, ROM size (specifically the number shown in Mb), SRAM size, bank type, and chips that this screen shows. With this information, we can determine exactly how we want to make this game.

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Step 2: Determine the method of reproduction

There are two ways you can make a reproduction cartridge. You can use a donor cartridge, which refers to taking an older game (hopefully a cheap, very common one) and removing the ROMs and replacing them with your own. The other option is to use a brand new board to make the game. There are pros and cons to each. But before we get into the nitty gritty details, your decision might already be made for you.

Look at the type of chips that uCon64 listed for your game. If this says anything EXCEPT a combination of ROM, SRAM, and/or Battery, you must use a donor cartridge. There are a handful of specific games that use special graphics chips. An example of this would be the game Star Fox 2. It uses a SuperFX chip to help with the graphics. Unfortunately, short of using a flash cartridge (which are very pricey), there isn’t any way to reproduce a game from scratch that uses these specialty chips. If you’re still unsure, you can check this game list Excel that I made, find your game, and check the furthest column. So once again, if you’re making a game that uses anything but the normal types of chips seen on a cartridge, you must use a donor cartridge. Skip ahead to Step 3a.

If your game uses normal run-of-the-mill chips, then you’ve got a decision to make! Let’s go over the differences between donor cartridges and custom PCBs.

Using a donor cartridge

Using a donor cartridge involves taking the Mask ROM chips off the existing board and replacing them with EPROMs or EEPROMs that you program yourself.

Pros to using a donor cartridge:

  1. You won’t have to supply your own plastic case.
  2. The cartridge comes with the necessary components, like RAM and the CIC lockout chip, and various resistors and capacitors on the board.
  3. Because of these, the price can be cheaper than using a custom PCB.

Cons to using a donor cartridge:

  1. You have to remove the existing Mask ROM (and possibly the battery), which can be a huge pain, and if done without caution, can easily damage the board.
  2. The assembly might look messy with a lot of extra wires, depending on the chips you use to program the game on.
  3. You’re destroying an otherwise good SNES game. If you’re a proponent of video game preservation (as I am), this might not appeal to you. Though, you’ll probably be destroying a crappy sports game, so use your best judgement.
  4. Removing stickers from cartridges is my least favorite part of the entire process. It seriously sucks.

Using a custom PCB

There are a few different sellers out there that will sell you PC boards that you can use in your SNES as cartridges – OR, you could use mine!!

Pros to using a custom PCB:

  1. The final build will look a lot cleaner, since you won’t need to rewire anything.
  2. You don’t have to spend time figuring out a compatible game to use as a donor cartridge.
  3. You can turn one into a testing board with sockets for all the chips so you can test games out before you solder them directly to the board.
  4. You’ll be supporting the SNES reproduction community! And you won’t be destroying a perfectly good soon-to-be-endangered SNES cartridge in the process!

Cons to using a custom PCB:

  1. You need to buy the board, extra components (such as SRAM, capacitors, and a lockout chip), and the plastic case, possibly making the final cost more expensive.
  2. You will only be able to make games that do not use specialty chips. Here is a list of games that you can make with my boards. It includes most games – any game up to 32 MBit that doesn’t use specialty chips, like the SuperFX.

Here’s a picture of a test board I made so I can swap chips in and out before soldering them on a permanent board. It’s very handy!

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Now that you have a better idea of how you want to make your game, let’s get the proper board.

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Step 3a: Choose your board (donor cartridge)

First, you’ll need to open up this Excel document I made. This document has information on most available ROMs for the SNES/Super Famicom, including all foreign games, and even some ROM hacks. I got the information for this spreadsheet from the SNES ROM Header Database. I trimmed some of the fat off of the list, like games that have weird amounts of SRAM or customized things that didn’t filter well in the Excel document.

Go back to your notes on the bank type, SRAM amount, and extra chips that your game uses. You should filter the columns for those characteristics to find a good, cheap donor. Note that instead of filtering the region column, you should filter the video column instead depending on if you’re in the NTSC or the PAL region. Making games from regions with different video encoding can be tricky, or impossible in some cases, and I won’t be covering it in this tutorial.

Say we wanted to find a suitable donor cartridge to make a Final Fantasy V English translation cartridge. The bank type for this game is HiROM, it uses 64Kbit of SRAM, and it has the normal chips plus a battery.

So, to find a donor cartridge, go to each of the filtered column drop down menus. Deselect each value that your game DOESN’T have in the Bank, SRAM, Chips, and Video columns. I also sorted the list by the game column from A to Z to group all common games together – makes it easier to sort through the titles. You should now have a list of compatible games.

chronodonor

Note that you should be sure that the game you pick isn’t a hack or mod itself, because that won’t be the cartridge you buy! Make sure the game you pick has an entry in the sheet that either has [!] or no additional information past a version number and region code (NOT translation code!). There are a few games that, for example, will use HiROM instead of LoROM if you have a certain translation or mod. You will be buying an original game so you MUST make sure the original is on your donor list!

Again using Final Fantasy V as the example, looking through the list you should see these: Earthbound, Final Fantasy III, Illusion of Gaia, Madden NFL ’95 through ’98, NBA Hang Time, NHL ’95 through ’97, Secret of Evermore, etc. So, theoretically, you could take an Earthbound cartridge and use it to make Final Fantasy V. I don’t recommend this, obviously, but it’s possible! How about we use something cheap that’s in retro video game bargain bins across the world, like Madden NFL ’95? Basically, any games that have the same characteristics in these important fields are interchangeable and can be used to make other games with the same characteristics. The good news is from what I’ve found, there are usually a wide variety of cheap games you can use to make most other games.

Now, if you want, you can check out your donor cartridge over on SNES Central. Note that the Mask ROM can come in a 32-pin or a 36-pin variety. Some games will have 36-pin sockets, but only use 32-pin ROMs. You’ll have a MUCH easier time with the reproduction if you get a board that has a 36-pin socket, so if you can, I recommend trying to pick a game that has that.

Once you have your donor cartridge, you should DEFINITELY check to see if it works as is in your SNES. You don’t want to get to the end of the process only to find the game you bought is broken (which has happened to me). Now, let’s decide the next most important aspect of your repro – what chips to load your ROM on. Head to Step 4.

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Step 3b: Choose your board (custom PCB)

I currently offer two boards – one that matches the original Mask ROM pinout on the SNES cartridges, and one that accommodates a 27C322 EPROM (one of these can hold all reproducible games, outside of Tales of Phantasia, Star Ocean, and some unofficial ROM hacks). These are available on my store page. They’re white, and they’re beautiful! They both support games up to 32 Mbit (and higher if you do some rewiring), and supports SRAM sizes up to 256 Kbit.

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Now let’s decide the next most important aspect of your repro – what chips to load your ROM on. This will determine which of my boards you’ll be using, so if you’re not sure which to use just yet, read on and figure out what works best for you!

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Step 4: Determine which memory chips to use

There are four widely used memory chips to load your ROM into that I will go over in this section. Which you choose will be determined by a few factors, most notably your ROM size, and if using a custom PCB, the compatibility of your board.

  • 27C801 – a through-hole 8 Mbit EPROM
  • 27C160 – a through-hole 16 Mbit EPROM
  • 27C322 – a through-hole 32 Mbit EPROM
  • 29F033 – a surface mount 32 Mbit EEPROM

There are plenty of alternatives with the same pinouts that will work just as well as these four (such as the M27C080 for the 27C801, or the 29F032 for the 29F033). I’ll be using these numbers when referencing these chips to make the tutorial easier to read.

For using donor cartridges, you can use any one or multiple amounts of these to make any game you want – for example, if your game is 32 Mbit large, you can use 4x 801’s, 2x 160’s, or one of the 32 Mbit chips. If your game is 8 Mbit large, you can still use one of the 160’s or 32 Mbit chips. Look at your command window again, and note the ROM size in Mb (megaBITS), so you know at least how much space you’ll need for your creation.

As far as my personal preference goes, I’ve been using 27C322’s for most of my repros lately, with a 29F033 that I use for testing purposes since it’s easy to reprogram them.

Checking your ROM in the SNES ROM Utility

Before you continue, you should download the SNES ROM Utility program and load up your ROM. If you get an error, you’ll be stuck working with the 27C801’s (as far as this tutorial goes), as we’re going to be using this program pretty heavily for all the other chips. Most games should load up fine though, the only games I’ve run into that gave me an error in the ROM Utility were BS games, or Japan-only games that were broadcast via Satellaview (by the way, if you’ve never heard of Satellaview, read up on it – it’s a super interesting piece of Nintendo history). Here’s what the error will look like.

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So again, if you see this error, you need to use 27C801’s (or similar). Anyway, onto descriptions of each of the memory chips you can use.

8 Mbit EPROMs

If your game is only 8 Mbit large, you can very easily and cleanly use just one of these EPROMs, like the 27C801. But it is important to note is that if you’re using multiple 27C801’s in parallel, you’ll need to also buy an extra chip, the 74HCT139 (or an equivalent decoder, like the LS139). These will cost on average about a dollar each. Using these through-hole parts makes it easy to solder, but very time consuming and messy, as you’ll need to add at least 40 individual wires. This is what a finished game will look like if you use 2 or more 8 Mbit chips, versus using a single 8 Mbit chip for a smaller game.

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See? The left picture is super ugly. And very time consuming. Also harder to troubleshoot. And fit inside the cartridge. I don’t really recommend using 27C801’s for anything other than 8 Mbit or smaller games, but if you’ve got a ton lying around, I’ll still go over how to use them later.

Extra hardware needed for using multiple 27C801 EPROMS: 1x 74HCT139 (or equivalent)

16 Mbit EPROMs

16 Mbit EPROMs, like the 27C160, I’ve found to run a bit cheaper than the 801’s. There are only two downsides to using these chips. It’s going to look ugly (unless you use some kind of adapter board), similar to the picture above, as it requires a lot of rewiring (there are 42 pins, so these chips won’t fit in the sockets), and you’ll need a special adapter to program these in the MiniPro programmer. Conveniently, I sell these on my store page! I’ll give you more details later, you can make your own as well if you’re into that. If you want to use two of these to make a 32 Mbit game, you can do that, but like using the 27C801’s in parallel, you’ll need a decoder, like the 74HCT139. Here’s what your game is going to look like with just one 27C160.

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Extra hardware needed for using 27C160 EPROMs: A programming adapter for the TL866
Extra hardware needed for using multiple 27C160 EPROMs: 1x 74HCT139 (or equivalent)

32 Mbit EPROMs

32 Mbit EPROMs are the largest through-hole EPROMs available. Luckily, nearly all SNES games are 32 Mbit or smaller. I use the 27C322. You’ll only need one of these chips for almost any game, and they aren’t too expensive, usually about $2 to $4 on eBay that I’ve seen. Even cheaper in bulk. But, like the 27C160’s, they will look ugly if you’re using a donor board – it has 42 pins, so you have to wire each pin individually to the socket correctly. Also like the 27C160’s, you’ll need an adapter to program them on the MiniPro, which I can provide you – check out the store page. Or, if you’d like, you can make a crude breadboard adapter yourself, but I promise it’s a lot easier to just get a pre-made adapter board like mine.

In addition to the EPROM, you’ll also need to attach the lines to a multiplexer, I use the 74HCT257 which is a quad 2-input multiplexer (you’ll need two of them). The 27C322 is a 16-bit EPROM, so the data is output in 16 bits rather than the 8 bits the SNES reads (don’t get this confused with the fact that the SNES is a “16-bit console”). In order to convert the 16-bit data to something the SNES can actually use, we’re going to connect the lines to two of these quad multiplexers and switch between the top and bottom 8 bits of the output of the chip. This means you’ll have to do some extra wiring.

If you wire everything externally like I described, your finished product will look like the one above where I used the 27C160. Alternatively, if you get a custom PCB (like mine), your final product might look a lot cleaner, like this:

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The following picture is using an adapter board that made it easier to mount to the board without having to use so many wires.

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Extra hardware needed for using 27C322 EPROMs: A programming adapter for the TL866, 2x 74HCT257 multiplexers

32 Mbit EEPROMs

As for the 32 Mbit EEPROMs (I used 29F033 chips), I got these from eBay for about $8 each. These are surface mount parts, so an extra breakout board is necessary to program and insert into the SNES PCB. For this, I bought breakout boards from buyICnow.com for $0.70 each (plus shipping). You’ll want to get the DIP36-TSOP40 Adapter (III). You’ll also need some header pins to use on the adapter board. The upside to using the 29F033 is that everything will look soooo much cleaner and the process will be much quicker, as you won’t need to do any rewiring. The downside besides the price is, well, it’s a lot harder to solder surface mount parts than it is through hole. If you don’t have any experience soldering surface mount, this might be a harder option for you, but if you’re feeling up to the challenge, go for it.

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The type of pins you’re gonna be soldering are circled in red in that picture above. So my advice, only if you are confident in your ability to solder extremely small pins and are willing to spend a bit of extra money to make your life easier, is to use the surface mount 32 Mbit EEPROMs with breakout board only for any game larger than 16 Mbits. It’s cheaper and faster, especially if you’re going to make a full 32 Mbit game. But again – this is a difficult process, especially if you’re new to soldering. And you might kill a few of these chips if you don’t solder them properly by keeping heat on the pins for too long. If you haven’t had a lot of experience in soldering such tiny pins, or aren’t willing to potentially waste a bit of money in damaged chips, I would recommend just using the through-hole EPROMs.

But if you feel so bold, my tips if you’re wanting to try to solder this surface mount chip: get yourself a flux pen. Flux will make your solder flow much better, and is essential if you want to attempt this (trust me… I tried to do it without it). Just spread it on all the pins. And maybe invest in an adjustable magnifying glass stand. Make sure you have really good lighting. And lay off the coffee… you need steady hands for this one. Here’s what a final board looks like with one of these EEPROMs. Very clean!

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Note that if you plan on going this route, and you want to use the TL866 programmer, you’ll need to either buy my adapter, or make your own to route the wires on the breakout board to the programmer.

Also note, custom SNES PCBs that have the original SNES Mask ROM socket (like mine) can accommodate these chips on adapter boards.

Extra hardware needed for using 29F033 EEPROMs: A TSOP-to-SOIC chip adapter, a programming adapter for the TL866

Note: If your game is larger than 32 Mbit, you will want to use TWO 29F033’s. Anything other than this will be very difficult to fit into a cartridge. This only applies to games like Tales of Phantasia or some ROM hacks, like Chrono Trigger: Crimson Echoes.

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Step 5: Expand your ROM and fix the checksum

Now you’ve chosen what kind of board you’re going to use and your chips, let’s take a look at that command window again.

cmd2

If the total size of your chip(s) is greater than the size of your ROM file, you should expand the ROM to fill up the total amount of space you have. To do that, use the program Lunar Expand. There’s some debate as to whether it’s really necessary to expand the game or not, but you might as well because it’s pretty easy to do.

Lunar Expand

Note: If your game is larger than 32 Mbit (for making Tales of Phantasia, or large ROM hacks, for example) then SKIP THIS STEP and go to the next section, IpsAndSum. I ran into some problems with these larger games, and I think the root of the problem was Lunar Expand.

Using Final Fantasy V above, we see that this ROM is 20 Mbit. That means I can either make a 24 Mbit game using three 27C801’s, use two 27C160’s, or use a single 32 Mbit chip. I’ll be doing the latter, so I need to expand the game to fill up all of the 32 Mbits. All you need to do is click your size option based on the total size of your chips (or combined chips), click “Apply to ROM…”, and choose your ROM file.

lunarexpand.png

If you expanded your game, you should run it through uCon64 again to double check the size, and to see if it changed the checksums at all.

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We see that the size is now 32 Mbit. Perfect! Well… almost.

IpsAndSum

Now, you need to make sure the checksums show “Ok.” In the picture above, my checksums are bad (this usually only happens when games are translated or modded). If they say “Ok” already, you’re good to go! Skip over this section. If your checksums are bad, then you need to run your game through a program called IpsAndSum. This program is a bit glitchy, but it’s pretty easy to figure out.

ips.png

First, you’ll need to go to File > Open, and choose your ROM. Sometimes the numbers will change in the fields on the screen, sometimes they’ll stay at 0000. Like I said, glitchy. Either way, go back to File > Repair SNES CheckSum, and the fields should change. Click Yes to repair. Then, make sure you go to File > Save to save your fixed ROM.

You should run the ROM through uCon64 once again to make sure the checksums got fixed, and that you remembered to hit File > Save (this happens more often than you’d think).

cmd4.png

At this point, if your checksums are still bad, you might have to try another ROM if possible, or try going through the steps again in case you missed something along the way. I’ve read that it might still work if you go ahead without good checksums, but I’ve never tried it as I haven’t run into that problem as of yet, so proceed at your own risk.

Removing the header and/or splitting the ROM

Don’t worry, you’re almost done. There’s one last program we’ll need to run your game through to prepare it. I mentioned it earlier, it’s the SNES ROM Utility.

Remember when we loaded up the game in the Utility earlier in the tutorial? If you got an error when you try to load the ROM, then you’ll have use a program called StripSNES (and 8 Mbit EPROMs) – skip this next section and go to the StripSNES section in Step 7a if this applies to you.

SNES ROM Utility

Here’s what the screen looks like when you load a ROM into it. The ROM I used for this example is Final Fantasy IV (my Final Fantasy V ROM didn’t have a header), which was expanded to be 16 Mbit and has fixed checksums, and DOES have a header.

snesromutility

You’ll see some of the information of the ROM here that you already saw in uCon64.

We’ve got a crossroads here. The process for preparing the different memory chips is varied. So, click on the link of the chips you’ll be using.

Step 6a: Finalize files for programming (27C801)

Step 6b: Finalize files for programming (27C160)

Step 6c: Finalize files for programming (27C322)

Step 6d: Finalize files for programming (29F033)

Back to top of Step 5


Step 6a: Finalize files for programming (27C801)

If you’re using the 8 Mbit EPROMs, there’s really only one option we’ll need to pick under the task list – SwapBin. This command does everything – it removes the header for us, splits the ROM file into 8 Mbit chunks for each EPROM we are using (if the game is larger than 8 Mbit), and performs a process (called “SwapBin”) that switches some of the bits around to make modifications a bit easier to the SNES PCB. Remember: do NOT use SwapBin if you’re using 16 Mbit EPROMs, 32 Mbit EPROMs, or the 32 MBit surface mount EEPROMs. (But if you’re using one of those, why are you reading this section? Go find the right one!)

snesromutility2

Check the SwapBin button, choose 27C801 on the drop down menu (probably the only option there) and click OK. You’ll get this notification, and if you look in the folder where your ROM was located, you should see a new file or files created. These are the files you will use. In this example for Final Fantasy IV, I will be using two 27C801 EPROMs. Therefore, the program created for me two separate BIN files for each of my EPROMs. You’ll also note at this point that the size of the files should match up with the size of the chip you’re going to use – each of the two files made for Final Fantasy IV are 1024KB large, or, 8 Mbits (because 1024 kilobytes is the same as 8 megabits).

Explanation of SwapBin

This is really only if you’re curious why we do this step. If you’re not, carry on to Step 7a.

Compare the pinouts between the SNES PCB EPROM and the 27C801 EPROM we are going to use. Like the NES, the SNES games use a proprietary pinout for the ROMs, so we need to do some rewiring.

epromvsmaskrom.png

However, many of these pins line up to other data pins. For example, pin 1 on the 27C801 is A19, but on the SNES PCB, this pin is A17. So, instead of having to rewire A17 and A19 to different places, we can use software to digitally swap these two pins by putting all the data from A19 to A17. That way, we effectively change the pinout of the 27C801, and this is exactly what the SwapBin command does in the SNES ROM Utility.

SNES ROM Utility switches A19 with A17 and A16 with A18. Now there’s only two extra wires we’ll have to solder for this EPROM to swap /OE and A16 (since /OE can’t be changed).

Now that you know why we’re doing this SwapBin business, skip ahead to Step 7a.

StripSNES

To reiterate, if you already were able to use the SNES ROM Utility, you do NOT need to do this part!

StripSNES works similar to uCon64, in that you need to use the command prompt. Follow the same steps for changing the directory as I laid out above in the uCon64 section, but enter the directory StripSNES is located within. Then, find your ROM, hold shift and right click, then hit “Copy as path.” Go to your command prompt window, enter:

stripsnes [path to ROM]

Use hit CTRL+V to paste the path. Hit enter, and not much will happen, but you should see the size of your ROM should decrease very slightly.

To make sure this worked, put your ROM back into uCon64 and check to see if the header is gone. While you’re here, you can split your ROM into 8 Mbit chunks, if you need to do that. To do this, simply enter:

ucon64 -s [path to ROM]

You should see a screen similar to this:

split

Go check in your uCon64 folder, and you should see the files listed at the bottom. In this case, since Final Fantasy IV was 16 Mbit, two files were created (SF16FINA.078 and SF16FINB.078). The one that ends with A will be the first EPROM, B will be the second. If you have more, C will be the third, and so on.

If you absolutely need to use this method with StripSNES and uCon64 splitting, then you will not have the luxury of swapping the pins as you get if you could use the SNES ROM Utility. There’ll be a bit more rewiring for you! But I’ll go into that later, don’t worry! Skip ahead to Step 7a.

Back to top of Step 6a


Step 6b: Finalize files for programming (27C160)

The 27C160 EPROMs are 42 pins wide. The TL866 programmer only has room for 40 pins. So how are we going to deal with that? Well, the short answer is, we’re going to trick the TL866 into thinking we’re programming a different EPROM. The EPROM we’re going to tell it to program is only 4 Mbits large. Using this EPROM normally would only utilize address pins A0 through A17. The 27C160 goes up to A19. By manually controlling A18 and A19, we can program our ROM in 4 Mbit chunks. Confused? Don’t worry, I’ll cover it in more detail later. For now, let’s just start with splitting our ROM into 4 Mbit chunks.

I’ll be using Final Fantasy IV as an example here. All you need to do is load your ROM into the utility, and check the “Split File” button. Then, on the drop down menu, pick 512kB (512 kilobytes = 4 megabits). Luckily, if the ROM has a header, the Split File option will automatically remove it for us when it splits!

snesromutility_16mbit

Since the Final Fantasy IV ROM is 16 Mbit, it will split into 4 separate files. Your folder should now contain multiple files that are 512 KB large.

ffiv_split

Now, skip ahead to Step 7b where we’ll program these chunks individually into our EPROM.

Back to top of Step 6b


Step 6c: Finalize files for programming (27C322)

The 27C322 EPROMs are 42 pins wide. The TL866 programmer only has room for 40 pins. So how are we going to deal with that? Well, the short answer is, we’re going to trick the TL866 into thinking we’re programming a different EPROM. The EPROM we’re going to tell it to program is only 4 Mbits large. Using this EPROM normally would only utilize address pins A0 through A17. The 27C322 goes up to A20. By manually controlling A18, A19, and A20, we can program our ROM in 4 Mbit chunks. Confused? Don’t worry, I’ll cover it in more detail later. For now, let’s just start with splitting our ROM into 4 Mbit chunks.

I’ll be using Final Fantasy V as an example here. All you need to do is load your ROM into the utility, and check the “Split File” button. Then, on the drop down menu, pick “512 kB”(512 kilobytes = 4 megabits). Luckily, if the ROM has a header, the Split File option will automatically remove it for us when it splits!

ff5_split

Since the Final Fantasy V ROM is 32 Mbit, it will split into 8 separate files. Your folder should now contain multiple files that are 512 KB large. I’ll explain why we’re splitting them into smaller chunks in the next section.

ff5_split_files.png

Now, skip ahead to Step 7c to learn how to program these chunks onto your chip.

Back to top of Step 6c


Step 6d: Finalize files for programming (29F033)

This step is super easy if you’re only using one 29F033 EEPROM. If when you load your game into the Utility, and it shows that it has a header, just check the “Remove Header” option and click OK. If you don’t have a header, then you’re already done! Go to Step 7d.

If you’re using multiple 32 Mbit EEPROMs because your game is larger than 32 Mbit, check the “Split File” option. Now, choose the “2048kB” option (2 Mbyte, or 16 Mbits) and click OK. The example below is for the English translation of Tales of Phantasia. It’s 6 Mbyte large (48 Mbits), so this will split it into 3 files, each 2 MByte large (16 Mbits).

pantasiasnesromutility.png

Now you should have 3 files in your folder that are 2 Mbyte large. That means we’ll have to stitch the first two together to get a full 4 Mbyte, or 32 Mbit, file for the first TSOP EEPROM, and put the last 16 Mbit file on the second TSOP EEPROM.

Here’s how your files should show up in your folder:

topfile

We need to stitch together the two files that end in 01 and 02 to make the file for the first EEPROM. We can do this easily in the command prompt, but first we should rename the files to something short to make it easier for us to type – let’s do ToP_01 and ToP_02.

Now, open a new command prompt window, and mount it to the folder your pieces of the ROM are in. Type in this command:

copy /B "ToP_01.sfc" + "ToP_02.sfc" ToP_A.sfc

This will create a new file, ToP_A.sfc, that will be a combination of both the files stitched together. MAKE SURE you have the order correct! This is what the command prompt should look like:

talescopy

Now, you should go ahead and rename the third file (the one that ends in _03) to ToP_B, for consistency. You should now have two files for Tales of Phantasia – ToP_A, which is 4 MByte (32 Mbit) large and will go on the first EEPROM, and ToP_B, which is 2 Mbyte (16 Mbit) large and will go on the second EEPROM. Note that the second EEPROM won’t be filled completely – this is OK. I’ve tested it and it still works with the second half of the chip empty.

If you have a ROM hack or other game that is 64 Mbit large, you’ll still need two 32 Mbit EEPROMs, like this example for Tales of Phantasia, but you’ll have to stitch the 03 and 04 files into one file using the same method. Now, skip ahead to Step 7d to find out how to program your EEPROMs.

Back to top of Step 6d


Step 7a: Burn your ROM (27C801)

As usual, make sure you blank check your EPROMs before you program them and clear them if necessary. I think you’re smart enough to figure out how to program your EPROMs with your programmer, especially if its the TL866 – it’s super easy to figure out. I believe in you! Program them as you would normally; if you’re using multiple ones in parallel, make sure you label them A, B, C, and/or D so you wire them in the correct order later. You’ll also want to tape over the little window so the games don’t get randomly corrupted sitting out on your desk.

(Don’t worry about the bent pins in this picture just yet.)

20170910_113444.jpg

Once you’ve programmed each chip, you’ll want to double-check that the code was programmed correctly. Most programmers have a “verify” function that will do just that. I highly recommend verifying your chips.

If you get an error while programming with the MiniPro – make sure your chips are in the correct orientation, blank, and that you’ve selected a 27C801 EPROM from the Select IC list!

Now go ahead and skip ahead to Step 8, where we’ll get our donor cartridge ready.

Back to top of Step 7a


Step 7b: Burn your ROM (27C160)

Burning your 16 Mbit EPROMs, as I mentioned before, requires you to trick the programmer. What we’re going to do is program the 4 Mbit chunks we just made, and manually change the A18 and A19 pins. You can do this yourself by making your own adapter, or you can buy mine.

The 27C160 is programmed through the data pins Q0 – Q15. This is a bit different than the 8 Mbit EPROMs and the 32 Mbit EEPROMs, which only use 8 data pins (Q0 – Q7). In its default state, the 160 is a 16-bit EPROM, though, we can make it output in 8-bit mode, which will be covered later. For now, we just need to know that we need to program our ROMs using all 16 bits.

As I said earlier, the TL866 doesn’t support the 160. However, it does support other, smaller 16-bit EPROMs, like the 27C4096. The 4096 is a 16-bit EPROM, however, it can only store 4 Mbit of data. Now… where have we heard 4 Mbits before? Oh right, the 4 Mbit chunks we made from our original ROM! So we’re going to trick the TL866 into thinking we’re programming the 27C4096, when in reality, we’re going to be programming our 27C160 and manually switching the top two bits, A18 and A19, between 0 and 1. This will give us 4 sections of 4 Mbit chunks, for a total of 16 Mbits. A18 and A19 represent what’s known as “banks” of data.

Using the ready made adapter (27C160 only)

If you’d like the adapter already made for you and save a bit of time and wires, then check out the store page. You’ll need to provide your own headers/sockets and two resistors. I also put a space for two DIP switches to make it nicer to switch A18 and A19, but you could always just use two wires to connect them (but, honestly, DIP switches are pretty cheap). Here’s what it looks like:

160adapter.jpg

R18 and R19 should both have values around 10 kΩ to 50 kΩ. They’re just standard pull-up resistors. If you’re interested in making your own adapter, you can check out the schematic and explanation of the operation over on my documentation page.

Using the ready made adapter (27C322/160)

Another option is the combination 27C322/160 programmer I’ve made. You can buy one on my store page! Here’s what it looks like:

etsy_322programmer_minipro2

For reference, the blue resistors (R2, R18, R19, and R20) above are 10 kΩ, and the other resistor (R1) is 220 Ω. You need to make sure that R1 is a low resistance, ideally around 220 Ω. The other resistors can be anywhere from 1 kΩ to 50 kΩ or so.

As you can use this adapter for the 27C322’s as well, make sure the switch is in the 27C160 position.

If you’re instead interested in making your own adapter, I provide the schematic and details of operation over on my documentation page.

Programming the 27C160

So now, you can get to programming. Load up the 27C4096 chip on the TL866 software, and load up the first file from your ROM (ending in _01). Change the VPP to 12.5 V, as this is dictated for programming voltage in the datasheet for the 160. Then, uncheck the “Check ID” option. Your window should look like this:

minipro160.png

Here’s a table of how data is programmed into the EPROM. If A18 or A19 is a “0”, that means tie it to GND, or if you’re using the adapter, put the switch in the “OFF” position. If it’s a “1”, that means tie it to VCC, or if you’re using the adapter, put the switch in the “ON” position. Program the 4 Mbit chunks that were made by SNES ROM Utility in sequential order in the banks.

banks.png

If you get an error while programming with the MiniPro – make sure your chips are in the correct orientation, each bank is blank, and that you’ve selected a 27C4096 EPROM from the Select IC list! Also, make sure you’ve got the switch on the adapter board on the 160 option (if you’re using the combination adapter board).

After you program your four chunks, repeat for your second EPROM if you’re making a bigger game. Then carry on to Step 8.

Back to top of Step 7b


Step 7c: Burn your ROM (27C322)

Burning your 32 Mbit EPROMs, as I mentioned before, requires you to trick the programmer. What we’re going to do is program the 4 Mbit chunks we just made, and manually change the A18, A19, and A20 pins. You can do this yourself by making your own adapter, or you can buy mine.

The 27C322 is programmed through the data pins Q0 – Q15. This is a bit different than the 8 Mbit EPROMs and the 32 Mbit EEPROMs, which only use 8 data pins (Q0 – Q7). We’ll have to add a bit of extra circuitry to use them in the SNES cartridge, but for now, we just need to know that we need to program our ROMs using all 16 bits.

As I said earlier, the TL866 doesn’t support the 322. However, it does support other, smaller 16-bit EPROMs, like the 27C4096. The 4096 is a 16-bit EPROM, however, it can only store 4 Mbit of data. Now… where have we heard 4 Mbits before? Oh right, the 4 Mbit chunks we made from our original ROM! So we’re going to trick the TL866 into thinking we’re programming the 27C4096, when in reality, we’re going to be programming our 27C322 and manually switching the top three bits – A18, A19 and A20 – between 0 and 1. This will give us 8 sections of 4 Mbit chunks, for a total of 32 Mbits. A18, A19, and A20 represent what’s known as “banks” of data.

Using the ready made adapter

If you’d like the adapter already made for you and save a bit of time and wires, then check out the store page. Here’s what it looks like:

etsy_322programmer_minipro2.jpg

As you can use this adapter for the 27C160’s as well, make sure the switch is in the 27C322 position (shown above).

If you’re instead interested in making your own adapter, I provide the schematic and details of operation over on my documentation page.

Programming the 27C322

So now, you can get to programming. Load up the 27C4096 chip on the TL866 software, and load up the first file from your ROM (ending in _01). Change the VPP to 12.5 V, as this is dictated for programming voltage in the datasheet for the 322. Then, uncheck the “Check ID” option. Your window should look like this:

minipro160.png

Here’s a table of how data is programmed into the EPROM. If A18, A19, or A20 is a “0”, that means tie it to GND, or if you’re using the adapter, put the switch in the “OFF” position. If it’s a “1”, that means tie it to VCC, or if you’re using the adapter, put the switch in the “ON” position. Program the 4 Mbit chunks that were made by SNES ROM Utility in sequential order in the banks.

322_table.png

If you get an error while programming with the MiniPro – make sure your chips are in the correct orientation, each bank is blank, and that you’ve selected a 27C4096 EPROM from the Select IC list! Also, make sure you’ve got the switch on the adapter board on the 322 option.

After you program your eight chunks, carry on to Step 8.

Back to top of Step 7c


Step 7d: Burn your ROM (29F033)

If you’re using the surface mount EEPROM with the adapter board I mentioned earlier, you’ll need to do a bit of extra wiring to accommodate for the breakout board. Nothing extreme! The good news is your board will look much cleaner in the end compared to the boards you make using the DIP package EPROMs from above.

Preparing the DIP36-TSOP40 Board

On the DIP36-TSOP40 adapter board, you might have noticed a few extra pads on the top of the board.

20170903_160404_markup

The pads we are going to worry about (R1 and R3) connect to the RESET and the /WE pins. These pins aren’t directly routed to any of the pins for the DIP package, as the SNES Mask EPROMs don’t use these pins. But, in order to program our 29F033, we need to do something about these pins. R1 connects the RESET pin to Vcc. This will ensure the chip is always on, which is obviously what we want. R3 connects the /WE (write enable) pin to pin 36 on the DIP package. This will be used by our programmer to enable writing the code to the chip, but when the adapter board is connected to the SNES PCB, this pin will be pulled to Vcc during operation, ensuring the chip never re-enters Write mode.

We need to short both R1 and R3. The easiest way to short these pads is to strip back a wire that covers both pins, solder both pads onto the wire, and then clip the remaining piece of wire. If you want, you could also spread some flux on the pads and short them that way, but be careful not to heat up the pads too much, because you don’t want them to fall off (which is something I’ve done…)

20170903_162959

You can completely ignore SJ1 and R2. Not necessary for our project.

Using the ready made adapter

Normally, to program surface mount chips, you usually need to get some sort of adapter for your programmer. They look like this:

adapter

All you do is drop your surface mount chip in the little box and make sure the pins are lined up, and you can program it like a normal through-hole chip. Now, these things are stupid simple. They’re literally just traces that reroute the tiny little pins on the surface mount package to larger, DIP-sized pins that your programmer accepts. I get that it’s a niche product, but still. I don’t want to drop extra cash on one of these things. If you think you’ll be programming a ton of these little guys, you can go ahead and pick one up, but I don’t use EEPROMs all that much outside of these reproductions.

With our DIP36-TSOP40 adapter board, we kind of have an adapter already. It’s just attached to a single chip. The problem is, this adapter board we have adapts the pinout to the SNES Mask ROM pinout, which is (unsurprisingly) NOT the same pinout that our programmer uses. So we have to make an adapter for our adapter.

You’ve got one of two options at this point. You can spend a lot of time wiring up your own breadboard adapter, which won’t cost anything if you have the supplies, or you can get a custom-made PCB adapter board (designed by me!) To buy this adapter board from me, head over to the store page.

etsy_tsopadapter_minipro.jpg

If you want to learn how to make your own adapter instead, head over to my documentation page. Once you have your adapter ready, place your chips in and blank check, clear if you need to, and program your game.

If you get an error while programming with the MiniPro – make sure your chips are in the correct orientation, blank, and that you’ve selected a 29F033 EPROM from the Select IC list!

If your game is going on two separate EEPROMs because it’s larger than 32 Mbit, make sure you label the EEPROMs accordingly! Also remember to verify the code afterwards to make sure it programmed correctly – most programmers have an automatic verify function.

Back to top of Step 7d


Step 8: Double check your chips, and prepare the donor board

You should definitely check off all these boxes before you go any further. Once you’ve soldered your chips in, getting them out is a risky and very frustrating process! I’ve killed at least a few boards because I ripped the pads off from desoldering and soldering so much. So ask yourself the following:

  • If using a donor board, is it compatible with my desired game?
  • Did the ROM run on an emulator correctly?
  • Did I remove the header from the ROM file?
  • Are there any broken traces on the board, specifically beneath where I will be placing the chips?
  • Is there any extra solder anywhere on the board that might be making unwanted connections?
  • Did I run ucon64 a final time to absolutely make sure the checksums are correct?
  • If I split the ROM into multiple chunks for multiple chips, did I label them correctly?
  • If I split the ROM into multiple chunks for the 160 or 322, did I program the banks in the correct order?

Making sure you’ve done these things will save you a lot of time and a lot of headaches, so make absolutely sure you’ve followed them. It might be useful to use the MiniPro’s verify function to double check and make sure everything programmed correctly – just load up the file you just programmed, connect your chip, and hit the “Verify” option. This will check the code you loaded in the software with the code that exists on the chip.

Now, if you’re using a custom PCB, you can skip ahead all the way to Step 9f. You’re nearly done!

As for you donor people, have you gotten all your materials from eBay in the time it took you to read through this wall of text yet?

SNES games can have a lot of different chips, but you’ll only need to worry about one at this point – the Mask ROM chips. You’ll want to keep all the other chips exactly where they are. Some games have two or three ROMs, but this is uncommon. If your game happens to have more than one, you’ll want to take all of them out. The ROMs are denoted on the PCB in some way, it’ll say “MASK ROM” or some variant of it. If your game doesn’t have any RAM or specialty chips, the ROMs will be the only large chips on your board.

20170906_224423_2

You can see above that U1 is labelled as MASK ROM, which is the chip we need to remove. U2 is the SRAM, which we want to keep in the board.

Removing the Mask ROM from their boards is kind of difficult, but you have a few options. The easiest way to remove these is to use a desoldering gun, that is, a soldering iron connected to a vacuum. A commenter suggested this model. These are pretty pricey and expensive to upkeep, so I don’t expect you have one of these, but your employer or school might let you borrow theirs! Another way to remove them is to use one of those desoldering pumps. I’ve never used one of these, but I know they’re kinda tedious to use.

desolder.png

Another easy option is to just take a Dremel and physically cut all the pins on the chip, then heat up each individual pin left in the hole with a soldering iron and use pliers to pull them all out. It’s not like you’re gonna need the Mask ROM when you’re done. Yet another option is to use copper wick to pull the solder off the pins. If you’re going to go this route, you should use some flux as well, to help the solder come off of the pins.

Whatever method you decide to do, make sure not to cut any other traces while you’re doing it! You’ll also want to get rid of all the extra solder left in the holes.

20170903_160504

Now that you’ve gutted your PCB and have your chips ready, it’s time to put them onto your board.

Step 9a: Install 27C801 EPROMs on the donor board

Step 9b: Install 27C160 EPROMs on the donor board

Step 9c: Install a 27C322 EPROM on the donor board

Step 9d: Install one 29F033 EEPROMs on the donor board

Step 9e: Install multiple 29F033 EEPROM on the donor board (ExHiROM games)

Step 9f: Populate your custom PCB

Back to top of Step 8


Step 9a: Install 27C801 EPROMs on the donor board

It’s very important to note – usually, the socket for the Mask ROMs on the PCBs has 36 holes. Like the NES, Nintendo made these boards usable for many different sized games. A 32-pin Mask ROM on a standard SNES game holds games up to 8 Mbit, and a 36-pin Mask ROM could (theoretically) hold up to a 64 Mbit game. Our 27C801 chips only have 32 pins, so we won’t be using the extra 4 holes – yet. You’ll see a little demarcation on the board denoting which extra holes are used for the 36-pin chips.

3236pin.jpg

Make sure when you put your (first) EPROM in the board that pin 1 of your EPROM lines up with pin 1 of the 32-pin socket (or pin 3 of the 36-pin socket). If you only have a 32-pin socket available, and you’re wiring more than one EPROM, you’ll have some special instructions.

Skip ahead to wiring two 27C801’s on board with two sockets
Skip ahead to wiring multiple 27C801’s on board with one socket

Wiring a single 27C801

If your game is 8 Mbit or smaller, you’re in luck, because this’ll be pretty easy for you. Luckily, unlike NES games, SNES PCBs are more or less universally wired. So this method will work for pretty much any game you want to make.

If you were able to use the SwapBin function on the SNES ROM Utility:

Your life will be easier if the SwapBin worked. Bend up pins 24 and 31 on your EPROM. Bend the pins SLOWLY and carefully using pliers to make sure they do not snap. Also, solder wires onto the socket holes 24 and 31. These don’t have to be super long, but you’ll have an easier time if you have ample room. Also, try to use thinner wires if you can. This will prevent putting too much stress on your EPROM pins so they won’t snap off.

20170913_180505.jpg

Now, place your EPROM with bent pins into the 32-pin socket. Solder the wire from hole 24 to EPROM pin 31, and solder the wire from hole 31 to EPROM pin 24.

20170913_181257.jpg

If you were NOT able to use the SwapBin function on the SNES ROM Utility:

If SwapBin did NOT work, then you’ll have to route three extra wires. No biggie. Bend up pins 1, 2, 24, 30, and 31 on your EPROM. Solder wires on the socket holes 1, 2, 24, 30, and 31. Place your EPROM into the 32-pin socket. Then, route the wires as below:

Wire from hole 1 to EPROM pin 30
Wire from hole 2 to EPROM pin 31
Wire from hole 24 to EPROM pin 2
Wire from hole 30 to EPROM pin 1
Wire from hole 31 to EPROM pin 24

20170909_144942

20170909_150322

Note that keeping the wires shorter (and using thinner wires) helps to make your game easier to fit back into the SNES cartridge. Skip ahead to Step 10 to test your game out!

Wiring multiple 27C801’s on a multi-ROM board

Some SNES games utilized two EPROMs on one board. Most of them just used a single, bigger, 36-pin EPROM, but not all. You will only be using this step if your game is 16 MBit, and you found a PCB that uses two EPROMs instead of one. You could probably make games bigger than 16 Mbit with these boards, but I haven’t gone through all the rewiring, and I don’t feel like it!

Basically, all you have to do is follow the same rewiring as in the section above for wiring a single EPROM, based on if you could SwapBin or not, but do it for both chips. Make sure that your first EPROM is inserted in the first EPROM slot, and the second is placed in the second slot. These are usually indicated by labels such as “P0” for the first chip and “P1” for the second. Here’s an example board with the P0 and P1 circled.

dualmaskrom.jpg

I haven’t encountered a board like this in my reproductions, but don’t hesitate to let me know if you have any problems with them! They can be tricky, and there are a few different models out there. That decoder chip can screw things up. Now, onto Step 10 to test out your game.

Wiring multiple 27C801 on a single-ROM board

So you’ve elected to use multiple 27C801’s. You’ve got the most work to do out of any of these steps. Not hard work, just tedious work. You’ve been warned! You’re going to want to double check that you programmed your EPROMs correctly (maybe use the “Read” function on the programmer) because taking this apart after you’ve constructed it will be a huge pain. What you’ll need are your EPROMs (marked for which one goes first, second, etc.) and the 74HCT139 decoder. You’ll also need a lotta wire. Different colors helps for debugging.

The first thing you’ll need to do is bend up the pins ONLY on your first EPROM as indicated in the above section based on if you were able to get SwapBin to work or not. This EPROM will be placed into the existing EPROM socket.

Next, solder wires from the holes indicated in the section on wiring a single EPROM, except pin 31 – leave that one empty. If you got SwapBin to work, that means a wire coming from hole 24. If you did not get SwapBin to work, that means holes 1, 2, 24, and 30 will have wires. Place your first EPROM (labelled “A”) into the socket and solder it in. Don’t worry about the bent up pins just yet.

Now, take your extra EPROMs and bend up pin 24 on each. Solder a wire on each pin for use later. Then, if you have more than one extra EPROM, solder all the pins on the extras together in parallel (except pin 24) – all pin 1’s soldered together, all pin 2’s, etc. Obviously, I don’t mean solder all the pins together in a giant solder blob. This can be done easily by physically stacking the chips (with pin 24 bent up) and soldering like so.

20170910_183731.jpg

Once you’ve paralleled all your EPROMs, solder wires from the extra EPROMs to the non-bent up pins of the EPROM on the board. It’s easier to access these pins with wire from the back of the board, but be sure you’re not getting too much wire in the way that would prevent you from closing the cartridge! If you’re using all three EPROMs stacked on top of each other, you’ll probably need to clip the bottoms of the pins so that the cartridge can close. This is also where the thin wire comes in handy.

Next, take care of the extra pins by following the steps indicated above where each wire should go – EXCEPT pin 24!

If SwapBin worked: connect the wire from hole 24 to the net of connected pin 31’s from all the EPROMs.

If SwapBin did not work: connect hole 1 to net of pin 30’s; connect hole 2 to net of pin 31’s; connect hole 24 to net of pin 2’s; connect hole 30 to net of pin 1’s.

You should have most of it wired up, and the extra bent up pin 24’s. So let’s take care of that, and the decoder. Follow this wiring diagram:

wiring

To be clear: you will only wire the red wires if your board has a 36-pin socket. If you only have a 32-pin socket, follow the wiring for the blue wires only, for now. EPROM “A” is installed on the board. If you don’t use all four EPROMs, just leave out the ones you don’t use. So for example, if you only have two EPROMs to worry about, then leave out EPROM “C” and “D” and leave pins 6 and 7 on the decoder disconnected.

A20 refers to pin 1 of the 36-pin socket, and A21 refers to pin 2 of the 36-pin socket.

Where you connect pin 1 on the 74HCT139 will be determined on the board you’re using. If your board has a MAD-1 chip on it, you will need to connect to pin 4 of that chip. The MAD chip (memory address decoder) is a type of memory mapper that is used on many boards. It’s also used for managing the RAM chip. Some older boards use a combination of an LS139 and a transistor to map the memory and control the RAM, but the MAD chip combines these two functions into one proprietary chip. If you do not have the MAD-1, you will have to find pin 49 on your connector, follow the trace back and confirm the connection with a multimeter, and then solder to that point. Here’s an example:

pin 49.jpg

If your Mask ROM socket only has 32 pins you will also have to find alternate connections for A20, A21, and VCC. VCC is easy enough, just solder it onto pin 32. A20 and A21 on the other hand could be in a few different locations. You’re gonna have to find another connection, like you did for pin 49.

Depending on what kind of board you have, a LoROM or HiROM board, your A20 and A21 pins will be on different parts of the cartridge connector! The only real difference that matters to us is that for LoROM games, the normal A15 pin is skipped, and all the data pins are shifted by one. If you’re curious about why this is, check out my SNES cartridge explainer, but I will not be getting into it here. But for our purposes:

LoROM has A20 on pin 46, and A21 on pin 47.

HiROM has A20 on pin 45, and A21 on pin 46.

cartconnectorhilo.png

So, find those pins, and follow the traces to an exposed solderable point on the board, and use that as your connection. If you’re confused, feel free to ask for clarification. After all of that, you should have some kind of mess of wires that looks like this:

multi8.jpg

 

If you’re curious how the decoder works, read on. Otherwise, go ahead and skip to Step 10 and test your game out!

What the decoder does

Here’s the functional diagram and truth table for the 74HCT139. We’re only going to focus on the top half, because that’s the only part we use.

decoder

A decoder is similar to a demultiplexer, but instead of switching an input to different outputs, it switches a set signal (in this case, logic LOW) to a different pin based on the inputs to A0 and A1.

In a game that is only 8 Mbit large, A20 and A21 are never used (because there are already 20 available data pins: 2^20 = 1 MegaBYTE, or 8 MegaBITS, which includes A0 through A19), and therefore we don’t need the decoder. But as soon as we go up above 8 Mbit to 16 Mbit, A20 is needed, which gives us 2^21 or 2 MegaBYTES, or 16 MegaBITS.

Pin 24 on the EPROMs is the /CE pin, or chip enable. This means that when the /CE pin is pulled LOW, the chip is able to operate. When the /CE pin is pulled HIGH, the chip turns off. If we tie the A20 and A21 pins to the decoder, we can activate different EPROMs and emulate having a single, larger EPROM by using multiple smaller ones.

So for example, if you have four EPROMs – if A20 and A21 are both LOW, the first EPROM is enabled which contains the first quarter of the game code. When the address line switches A20 to HIGH, we completely switch EPROMs and now read information from the second EPROM. When A21 is activated with A20 off, this makes the SNES read information from the third EPROM. And finally, when both A20 and A21 are HIGH, the last EPROM is connected.

This is why all the EPROMs are connected in parallel – only the one that is currently selected by the SNES through data lines A20 and A21 will output data on these lines. The other pins on the deactivated EPROMs will simply be set to a high impedance mode, effectively making them disconnected. Overall, this gives us extra data pins and emulates having a single, larger EPROM. Time to test your game out in Step 10.

Back to top of Step 9a


Step 9b: Install 27C160 EPROMs on the donor board

The 27C160 EPROMs are 16 Mbit EPROMs, but that data output can be organized as 8 bits long, or 16 bits long. If the chip is in 8-bit mode, you can store up to 2 Mbit address locations on the A pins. If it’s in 16-bit mode, you can store up to 1 Mbit address locations on the A pins. Since the SNES reads data in an 8-bit bus, we need to put the EPROM into 8-bit mode. This is done by setting the /BYTE pin to LOW logic, or connected to GND. Doing this causes pin 31, labelled as Q15A-1, to act as the new A0, and offset all the address pins by 1 location. So, essentially, A19 will become A20, A18 will become A19, and so on.

Wiring a single 27C160

Wiring only one of these babies isn’t hard at all, just a bit tedious. Just follow this handy table down below. You need to wire the pins from the 27C160 to the corresponding socket number on the SNES cartridge. So, for example, pin 1 on the 27C160 goes to hole 32 on the SNES board.

160toSNES

If your cartridge only has a 32-pin slot, then still follow the table above, but you’ll have to find an alternate location to connect pin 42 from the 27C160 to. Follow A20 from the cartridge connector to somewhere you can solder onto. LoROM boards have A20 on pin 46 of the cartridge connector. HiROM boards have A20 on pin 45.

cartconnectorhilo.png

So, find those pins, and follow the traces to an exposed solderable point on the board, and use that as your connection.

When you’re done, it’ll look something like this mess.

m27c160.jpg

Pro tip: don’t be like me, use small gauge wire! It’ll make it look nicer, fit in the cartridge easier, and also put less stress on the pins. I just got too impatient to wait for my smaller gauge wire to come in the mail. Now, skip ahead to Step 10 to see if your hard work has paid off!

Wiring two 27C160

Wiring two of these 16 Mbit chips in parallel will allow you to make most games. This is very similar to wiring up multiple 8 Mbit EPROMs. You’re going to want to double check that you programmed your EPROMs correctly (make sure your programmer is verifying the code) because taking this apart after you’ve constructed it will be a huge pain. What you’ll need are your EPROMs (marked for which one goes first and which goes second) and the 74HCT139 decoder.

The first thing you’ll need to do is bend up the /OE pins on the two EPROMs. That’s pin 13. Now, solder all the pins on the extras together in parallel (except pin 13) – all pin 1’s soldered together, all pin 2’s, etc. This can be done easily by physically stacking the chips (with pin 13 bent up) and soldering like so. The picture below is from the section above. It’s showing two 8 Mbit EPROMs soldered together, so yours is gonna look different. But the principle is the same. You’ll just have 41 pins to solder together.

20170910_183731.jpg

Once you’ve paralleled your EPROMs, solder wires from the board to pins of the EPROM on the board, by following this table below. But keep pin 13 unwired at this time.

160toSNES_multi.png

As usual, I recommend small gauge wire to make these connections. You’re gonna have a lot of wire to handle. You’ll also probably need to clip the bottoms of the pins so that the cartridge can close. If you only have 32 pins on your board, wire everything according to the table normally, and keep the A19 pin on the 27C160 disconnected for now.

You should have it wired up, except the bent up pin 13’s. So let’s take care of that, and the decoder. Follow this wiring diagram:

wiring160.png

To be clear: you will only wire the red wires if your board has a 36-pin socket. If you only have a 32-pin socket, follow the wiring for the blue wires only. A21 refers to pin 2 of the 36-pin socket.

Where you connect pin 1 on the 74HCT139 will be determined on the board you’re using. If your board has a MAD-1 chip on it, you will need to connect to pin 4 of that chip. The MAD chip (memory address decoder) is a type of memory mapper that is used on many boards. It’s also used for managing the RAM chip. Some older boards use a combination of an LS139 and a transistor to map the memory and control the RAM, but the MAD chip combines these two functions into one proprietary chip. If you do not have the MAD-1, you will have to find pin 49 on your connector, follow the trace back and confirm the connection with a multimeter, and then solder to that point. Here’s an example:

pin 49.jpg

If your Mask ROM socket only has 32 pins you will also have to find alternate connections for A20 (A19 from the 27C160), A21 (pin 2 from the 74HCT139) and VCC (pin 16 from the 74HCT139). VCC is easy enough, just solder it onto pin 32 of the EPROM socket on the board (pin 34 in the table above, labelled “VCC”), or pin 22 on the 27C160. A20 and A21 on the other hand could be in a few different locations. You’re gonna have to find another connection, like you did for pin 49.

Depending on what kind of board you have, a LoROM or HiROM board, your A20 and A21 pin will be on different parts of the cartridge connector! The only real difference that matters to us is that for LoROM games, the normal A15 pin is skipped, and all the data pins are shifted by one. If you’re curious about why this is, check out my SNES cartridge explainer, but I will not be getting into it here. But for our purposes:

LoROM has A20 on pin 46, and A21 on pin 47.

HiROM has A20 on pin 45, and A21 on pin 46.

cartconnectorhilo.png

So, find those pins, and follow the traces to an exposed solderable point on the board, and use that as your connection. If you’re confused, feel free to ask for clarification. Otherwise, skip ahead to Step 10 to test out your board!

Back to top of Step 9b


Step 9c: Install a 27C322 EPROM on the donor board

If you look at the pinout of the 27C322, you’ll notice the data pins go from Q0 to Q15. As I mentioned earlier, that’s because this is a 16-bit EPROM, where each word is 16 bits instead of the 8 bits the SNES uses. When we programmed our 322 using our ROM that was meant for reading in 8 bits, we smashed two 8-bit words into one 16-bit word. So the first address of the 322 contains the first TWO addresses the SNES will use.

Compare the left window here, which is an 8-bit EPROM, with the 16-bit EPROM on the right. Again, these numbers are in hexadecimal, or four binary bits. So you’ll see on the 8-bit bus two-digit hex numbers, while on the 16-bit bus you’ll see four-digit hex numbers.

8bitvs16bit.png

Let’s use the first two addresses, which are 0x78 and 0x18, as an example. If on a 16-bit EPROM we read only D0 to D7 (0x78), we’re completely missing all the data on D8 to D15 (0x18) – with each increasing address request from the SNES, we’re skipping every other 8 bits segment. In effect, on a 16-bit EPROM, A0 from the SNES should point to the bottom half (A0 = 0) or top half (A0 = 1) of each word. And therefore, A1 from the SNES is acting like the 27C322’s A0 pin. So all we have to do is shift the address pins from the SNES one position – A1 on the SNES is connected to A0 on the 322, A2 on the SNES is connected to A1 on the 322, etc. Then, we use the A0 pin from the SNES to control which half of the 16-bit word we read from. We can do this using a multiplexer.

A multiplexer is a device that is essentially a digitally controlled selector switch. In our case, we need eight separate switches to change between two different data lines all at the same time. D0 on the SNES should either read D0 or D8 from the 322 EPROM, D1 on the SNES should either read D1 or D9 from the 322 EPROM, and so on. When A0 from the SNES is 0, the multiplexer will route D0 to D7 from the 322 to the SNES, and when A0 from the SNES is 1, the multiplexer will route D8 to D15 from the 322 to the SNES. Make sense?

mux

The 74HCT257 is a quad-package two-line multiplexer. If we use two of them in parallel, we can control all eight data lines. So, you’ll want to follow this table to connect your cartridge, multiplexers and EPROM:

322_table_tosnes.png

If your cartridge only has a 32-pin slot, then still follow the table above, but you’ll have to find alternate connections for A20 (A19, or pin 42 on the 27C322) and A21 (A20, or pin 32 on the 27C322). Follow A20 and A21 from the cartridge connector to somewhere you can solder onto. LoROM boards have A20 on pin 46, and A21 on pin 47 of the cartridge connector. HiROM boards have A20 on pin 45, and A21 on pin 46 of the cartridge connector.

cartconnectorhilo.png

So, find those pins, and follow the traces to an exposed solderable point on the board, and use that as your connection.

Here’s a schematic of how you’ll want to connect the multiplexers, if it’s easier for you to follow. I won’t include a schematic of where the EPROM pins go, since it’s a lot easier to just follow the left side of the table above.

322_mux_schem.png

When I went to wire this, I only had surface mount multiplexers lying around, but you can use through-hole for easier soldering. Instead of soldering wires to the little surface mount pins, I used a 27C322-to-SNES adapter (coming to a store near you soon!).

322_onboard_2.jpg

Now, head to Step 10 and we’ll finish up the game.

Back to top of Step 9c


Step 9d: Install one 29F033 EEPROM on the donor board

If you are using the one 29F033 chip, your life is comparatively easier at this step. If you’re going to be using two 29F033’s, you need to skip ahead to Step 9e. If not, just plop your little adapter board into the place where the other ROM was. Make sure you’re putting in the chip in the correct orientation!

20170903_162933-e1504750339546.jpg

You need to make absolutely sure your game is programmed correctly before you solder it into the socket. You don’t want to spend all that extra time desoldering a chip you found out was programmed incorrectly! Once you’re sure, go ahead and secure the header pins with solder and trim the bottoms off. In the picture below, the top row is uncut, and the bottom row is cut.

20170903_163225.jpg

You can see the difference! Be careful when you’re clipping these – you don’t want one to fly into your eyeball. This has happened to me. It is not pleasant. Clip them into a trash can or something.

If your game only has 32 pins for the socket:

You will need to rewire pins 1, 2, 35, and 36 to their proper locations. You’ll also probably need to trim the bottoms of the pins off so that the other 32 pins still fit in the socket. Pin 1 is A20, pin 2 is A21, pin 35 is A22, and pin 36 is VCC. You can connect pin 36 to pin 34 with a jumper cable easily enough.

As for the other data pins, you’ll need to connect them to some other point on the board – this can vary depending on the board you have. All you have to do is find the correct pin on the cartridge connector, and follow the trace back to a solderable point. Hopefully there’s somewhere on the board you can connect to, but if there isn’t, you might have to solder onto the top of the connector. This should be pretty rare, though.

Depending on what kind of board you have, a LoROM or HiROM board, your A20, A21, and A22 pins will be on different parts of the cartridge connector! The only real difference is that for LoROM games, the normal A15 pin is skipped, and all the data pins are shifted by one. This also means that LoROM games don’t ever utilize A22. If you’re curious about why the pins are shifted, check out my SNES cartridge explainer, but I will not be getting into it here. But for our purposes:

LoROM has A20 on pin 46, and A21 on pin 47.

HiROM has A20 on pin 45, A21 on pin 46, and A22 on pin 47.

cartconnectorhilo

If you’re still confused, feel free to email me. Now, go ahead and skip to Step 10.

Back to top of Step 9d


Step 9e: Install multiple 29F033 EEPROM on the donor board (ExHiROM games)

As far as I know, the only games that use the ExHiROM style of board are Tales of Phantasia, and Daikaijuu Monogatari II, both only released in Japan. Unfortunately, the latter uses a unique real-time clock chip that isn’t used in any other game, so you won’t be able to make this game. So really, this section is mostly for Tales of Phantasia – which is an EXCELLENT game that I highly recommend making!

If you want to make a game that is larger than 32 Mbits, but isn’t ExHiROM, you will need to follow different directions. This would include games like ROM hacks, such as Super Demo World, or Chrono Trigger: Crimson Echoes. These games still use the HiROM or LoROM mapping style, but will require two 32 Mbit EEPROMs. I recommend following this post on NintendoAge. I haven’t built a game like this yet, but when I do, I will add a section for it!

Anyway, Tales of Phantasia uses the normal chips, plus 64Kbit SRAM, so you should have a board that has these characteristics. You should also have two programmed 32 MBit EEPROMs on the TSOP adapter boards, marked A and B.

Note: I’ll be making this game with a board that only has one 36-pin socket for EPROMs – instructions for making this with a board with two EPROM sockets, or a 32-pin socket, will be a bit different, so be aware of that. I will not be covering those situations here.

The first thing you’ll need to do is remove your MAD-1 decoder from the PCB. Here’s what your board should now look like, and the components you’ll be using.

20170927_221729.jpg

Bend up pin 13 on the MAD chip, and place it back into the board. If it’s easier for you, you can try just cutting the pin without removing the chip, but make sure you can still access pin 13 coming from the MAD-1 chip.

20170928_213533.jpg

Now, remove pin 33 from the header on the FIRST EEPROM. This is the /OE (output enable) pin, which will be controlled by the MAD-1 chip. Put the EEPROM in the socket, making sure it’s in the correct orientation, and solder it in. Remember, you’ll be missing pin 33, so don’t solder anything on that. Do NOT trim the header pins on the back yet!

Now, you have one of two choices. If you want a cleaner looking assembly, remove the header pins on the SECOND EEPROM adapter board. Make sure all the solder is out of the holes, and place it on the back of the board on the header pins from the FIRST EEPROM, like a sandwich. Make ABSOLUTELY SURE the board is facing the exact same orientation as the first board so that pin 1 on “A” is connected to pin 1 on “B” and so on. You don’t want to put it in backwards or upside-down!!

20170928_223905_edit.jpg

If removing the header pins is too much of a pain for you (completely understandable), then you can connect each pin from EEPROMs “A” and “B” together with wires, much like you do when using multiple 8 Mbit EPROMs. But, make sure you do NOT wire the pin 33’s together!

Now, you should have a board with two TSOP adapter boards connected in parallel, either through wires or the sandwich method, with pin 33 disconnected to everything on both boards. You should also have a MAD-1 chip with a floating pin 13.

Connect pin 13 on the MAD-1 board to pin 35 on the TSOP adapter boards. Make sure both pin 35’s are connected! Then, run a wire from the “A” EEPROM pin 33 to pin 1 on the MAD-1 chip. Finally, run a wire from the “B” EEPROM pin 33 to pin 16 on the MAD-1 chip. Note that pin 1 and 16 on the MAD-1 chip are still in the board – this is because they’re not connected to anything on the board anyway, so we don’t have to pull them out. You can access them from the top of the board, or the back of the board. Here’s what it should look like afterwards (I used the sandwich method):

20171005_201000.jpg

20171005_201006.jpg

Now, you’re nearly done! Skip over to Step 10!

Back to top of Step 9e


Step 9f: Populate your custom PCB

Alternatively, you can view the quick guide if that’s your thing.

Depending on the board you have, you’ll need to do a few different things to get it up and running. Some boards might even ship with the necessary parts you’ll need to make your game. I’ll go over some of the common requirements for these boards, starting with the CIC chip.

As I mentioned earlier, the CIC chip is basically the region-locking chip. Every cartridge has one. It interfaces with a CIC chip on the SNES console to check and make sure the region is correct. So any game we make is gonna need one itself. If you’ve got an extra one from an old game lying around, you can always use that, but luckily there’s a simple way to make one from a microcontroller. All we have to do is program a PIC12F629 with the “SuperCIC” code from the SD2SNES blog (based on the work from Segher at HackMii). Luckily, the MiniPro programmer we have has the capability to program the PIC.

How to program the SuperCIC

Once you’ve got your PIC and downloaded the code from SD2SNES, extract the folder and find the file named “supercic-key.hex” and MAKE SURE it ends with -key, NOT -lock. Now, open the TL866 software, and go to Select IC(S) to search for the 12F629. It’ll probably show up as PIC12F629, so choose that one. Then, load up supercic-key.hex, and program away!

20180624_153654-e1532906003838.jpg

supercic.png

You shouldn’t run into too many problems, it’s a pretty simple process.

Using My Custom PCB (SNES Mask ROM)

A lot of the board is self explanatory. Here’s what the front of the board looks like:

pcb_snesmask_2_2

So, easy things first. The CIC chip we just programmed above goes on the bottom left of the board. C1 is for the electrolytic capacitor – these were 22 uF on the original SNES boards, so something around there should be sufficient (make sure it’s rated for at least ~10 V or higher). C2 and C4 should be used in all situations, I use something around 0.1 uF – these are to filter out any electrical noise that could corrupt data.

If your game uses any kind of SRAM, you’ll need to populate the rest of the board. The SRAM chip goes up on the top right of the board. I included sockets for the common “slim” package and the “wide” package SRAM chips. The board supports the 64Kbit or 256Kbit chips (6264 and 62256, respectively). If you’re using the slim packages, make sure you use the bottom and middle rows of through holes. Also, be sure to populate C3 similar to C2 and C4. You’ll need a 139 decoder chip as well (like the 74HCT139 – I have the surface mount package on the board, which is fairly easy to solder). Finally, the battery should be installed and R1, R2, D1, and D2 as well. I use ~220 Ω for R1 and R2, and small 1N914 diodes for D1 and D2 – make sure to get the polarity correct!

Now let’s take a look at the back of the board.

pcb_snesmask_2_2_back.jpg

The most important part of this board are the 3-way jumper pads on the bottom right. You need to add a solder bridge to every one (from the middle pad to either the left or right) based on if your game is a HiROM or LoROM bank type. They’re pretty close together so it shouldn’t be hard to bridge them with solder, but if you’re having trouble, you could use a bit of wire too. If your game is LoROM with no SRAM, you additionally need to bridge all three pads together on the bottom right set of pads.

If your game uses SRAM, solder the jumpers in the top middle based on how large the SRAM is. For example, if your game uses 64K SRAM, bridge the top two right pads, and the bottom two left pads. Don’t forget to bridge the pads on the left as well if you’re using SRAM.

The three pads on the bottom left of the board need to be soldered together when you put the game in. The reason I added these pads here is if you desolder the two pads, and you leave the header pins on a 29F033 adapter board sticking out long enough from the back of the socket, you can reprogram the EEPROMs using the TL866 adapter board. Neat!

Finally, the EPROM or EEPROM of your choice should be assembled in the Mask ROM socket. Follow any rewiring (like for the 27C801 pin swap) in the previous steps. Eventually, I will have updated boards that accommodate these pin changes.

Using My Custom PCB (27C322)

This board is very similar to the SNES Mask ROM board. Here’s the front:

pcb_322_2_2

So, easy things first. The CIC chip we just programmed above goes on the bottom left of the board. C1 is for the electrolytic capacitor – these were 22 uF on the original SNES boards, so something around there should be sufficient (make sure it’s rated for at least ~10 V or higher). C2 and C4 should be used in all situations, I use something around 0.1 uF – these are to filter out any electrical noise that could corrupt data.

If your game uses any kind of SRAM, you’ll need to populate the rest of the board. The SRAM chip goes up on the top right of the board. I included sockets for the common “slim” package and the “wide” package SRAM chips. The board supports the 64Kbit or 256Kbit chips (6264 and 62256, respectively). If you’re using the slim packages, make sure you use the bottom and middle rows of through holes. Also, be sure to populate C3 similar to C2 and C4. You’ll need a 139 decoder chip as well (like the 74HCT139 – I have the surface mount package on the board, which is fairly easy to solder). Finally, the battery should be installed and R1, R2, D1, and D2 as well. I use ~220 ohms for R1 and R2, and small 1N914 diodes for D1 and D2 – make sure to get the polarity correct!

Now let’s take a look at the back of the board.

pcb_322_2_2_back

The back is a bit busy, but it’s nothing terribly complicated. The first thing you should populate are the 257 multiplexers needed with the 27C322 EPROM. I generally use the 74HCT257 multiplexers, but any 257-type chip will work fine. Please note these are surface mount!

The most important part of this board are the 3-way jumper pads on the bottom right. You need to add a solder bridge to every one (from the middle pad to either the left or right) based on if your game is a HiROM or LoROM bank type. They’re pretty close together so it shouldn’t be hard to bridge them with solder, but if you’re having trouble, you could use a bit of wire too. If your game is LoROM with no SRAM, you additionally need to bridge all three pads together on the bottom right set of pads.

If your game uses SRAM, solder the jumpers in the top middle based on how large the SRAM is. For example, if your game uses 64K SRAM, bridge the top two right pads, and the bottom two left pads. Don’t forget to bridge the pads on the left as well if you’re using SRAM.

Now, just put your 27C322 EPROM into the socket, and you’re good to go!

Back to top of Step 9f


Step 10: Finish your game

When you put your board back in the cartridge, you’re probably going to want to clip the little plastic stand-off on the back of the cartridge, especially if you used the TSOP adapter board because that’s gonna get in the way.

20170903_163910.jpg

Now close your game back up nice and tight. If you did everything right, you should be playing your game just fine! If not…. well here’s a few things you can try to fix it.

Troubleshooting tips

Just as a suggestion, if I were you, I’d invest in making a dedicated prototyping board with proper sockets for things like your EPROM and maybe your CIC chip (if you’re making a SuperCIC). I have a few special boards set aside with these sockets so I can swap these chips in and out to test games before I solder them directly to the board. It’s pretty easy to make some test boards using my custom PCBs, so check them out if that sounds like something you’d like to try.

Before you try anything, check to see if your game is LoROM bank type, uses SRAM, and has the 74LS139 decoder. If this applies to you, try taking the decoder out and rewiring as such:

ls139rewire_lorom

If this is the case for you, except your board is HiROM, let me know and I’ll look at the wiring. The only boards I know that would fit this description for HiROM games are expensive ones that you probably aren’t using as donors, but I might have missed one.

If this doesn’t apply to you, here’s some tips you should follow before you give up. This is the order I would try them in – it’s listed from shortest to longest amount of time to check. Please do these things before you message me or leave a comment, cause I’m gonna ask you if you did before anything else!!

  • Check for any cold solder joints. They’ll be recognizable by their “misty” or “crumbly” appearance. To fix them, just heat them up (and make sure they’re heated sufficiently) and put some new solder on them.

cold

  • Also, make sure you didn’t miss any pins or wires. You’ll have a lot to solder, after all. It only takes a single pin to be disconnected to screw up the whole thing.
  • Make sure your SNES works with other normal games. I know this sounds silly, but you never know if your SNES just kicked the bucket or not between games. I once bought Super Mario RPG and the sound didn’t work – but it wasn’t the game, it turns out my SNES audio fried since I last played!
  • Check to make sure all your chips are in the correct orientation – especially for custom PCBs, where you have to provide many chips yourself.
  • Check to make sure you didn’t cut any traces on the board accidentally – if you did, you’ll have to add a replacement wire.
  • If you’re using a donor, did you remember to test the original game before you took the EPROM out? Maybe something else is damaged on the board, and it’s not your fault. Try replacing the capacitors (smaller ones are 0.1 uF, the large electrolytic is 22 uF). Clean the contacts that go into the SNES on the cartridge. Use like rubbing alcohol or something, look online for resources, I’m not good at housekeeping stuff.
  • Finally, even if you THINK everything is connected correctly, use a multimeter and check the continuity of each pin on your EPROM or other chips to its destination. This means testing the cartridge connector in some cases. Follow the pin tables and/or schematics for the type of memory chip you chose up in Step 9. This is arduous – but any time I was stumped, I usually found that just one of the pins I thought was connected wasn’t in reality. Refer to this table below for the pinout of the cartridge – you only really have to test the address pins (A0 – A23), data pins (D0 – D7), GND and Vcc pins. Everything else should have been left alone.

 

cartconnector.png

If all else fails, you might have to desolder your chip, blank it, reprogram, and try again. Unfortunately, it’s hard to troubleshoot these boards sometimes (especially online) but if you have any questions, feel free to leave them below in the comments, or shoot me an email.

Make a label

This part is completely optional! If you want your new Final Fantasy V cartridge to look like a Madden football game, you do you! But if you want something that looks a bit nicer, read on.

First things first, you gotta get that pesky label off of your game. You’re gonna want to just focus on the front cover, obviously. You can try to take the label off by hand, but I’ve never been able to get it completely off. Always get a ton of extra residue and paper.

I found a solution that works pretty well, though. All you have to do is mix equal amounts of baking soda and vegetable oil – you only need about a tablespoon. Rub it on all the leftover sticker and let it sit for half an hour. Afterwards, scrub it clean with some steel wool or your fingernails or whatever, it should come off pretty easily. Wash it off and you should have a blank canvas on which to work. I’ve also seen that soaking the cartridge in water for an hour or two will make the paper soft, and you can rub it off with your fingers.

20170903_172833.jpg

Now, you need to get a new sticker for the front! You can either buy them online at various shops for $5 or $6, which might be the most convenient for you, or you can print them yourself if you have a good enough printer (or if your game doesn’t actually have a label). It might be cheaper to just buy them individually if you’re not planning on making a whole lot of games. Maybe see if your local office supply stores sell these in single sheets or will print them on the paper for you?

If you want to make your own label, use this template. I found it on DeviantArt.

snes_label_template__usa__by_michaelmannucci-d7smne9

Then, you can use your favorite photo editing software (I prefer GIMP, which is a free Photoshop-esque program) to place your own picture and name. Search for pictures of your game on Google or something as a reference.

Now, you’ll want to make sure the size matches up for when you print them out. The SNES labels need to be approx. 1.77” x 3.25” when cut. I’m not a wizard at getting this to line up correctly, so you’re on your own for this.

You can use full page sticker sheets and cover them with lamination paper. It’s more economical to fill up a whole sticker sheet with labels, then cover it with a full sheet of lamination. Buying a full package of these sticker and lamination sheets can get a bit pricey, though. A suggestion from mrTentacle is to print the label on vinyl sticker sheets, then spray them with a fixative. The sticker sheets he uses are similar to these and the finish material is similar to this.

Back to top of Step 10

Conclusion

It’s been a long time coming, but finally, you’ve completed your first SNES game! Feeling good about yourself? You should be!

Remember that selling reproductions of released games is technically illegal! And don’t go to conventions trying to sell them, passing them off as legitimate! That’s called being a jerk. Don’t rip off genuine game collectors, we’re nice people.

Hopefully this guide was comprehensive and detailed enough to give you a good understanding of what to do and why we did it. If any part is unclear, if I have any mistakes, or you need help figuring out your board, feel free to email me, and I will do my best to clarify or fix the problem! I still plan on continuously updating this tutorial but let me know what you wanna see most, and I’ll try to focus on that if there’s enough of a demand!

Until then, tinker on my fellow hobbyists!

I got a lot of my information from the NintendoAge forums and the NesDev forums. Check them out – they’re amazing! Also, special thanks to Michael at AmpereSandRepros for his board donations, and Martin Samuelsson (mrTentacle) for his board and chip donations and for helping myself and others in the comments section.

And if you’d like to purchase any of my materials, head over to the store page and I’ll be happy to hook you up!

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299 thoughts on “How to Make a SNES Reproduction Cartridge

  1. Hi, i have a problem making a repro (actually is a zelda hack repro), rom size is 4MB, i tried to make it using two 29f016 chips, so i split rom into two using snesromutil (prior that i patch the rom, verify that sum check is ok) and i programmed my chips, also I´m using an shvc-ba3m-20 board (https://snescentral.com/pcbboards.php?chip=SHVC-BA3M-20) due it can accept two chips only by soldering them, game boots but after a short time graphics gone wrong (sometimes even freezes in the intro), I know my fullrom file is ok, cuz using a 29f033 chip in a test board that only accepts one chips games plays correctly, so my question is, do you know if using a board that accepts two chips needs to be modify, cuz i double checked that there is no solder bridge on any of the 29f016 chips. Sorry for my bad english, is not my native language. Greetings.

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    • So I’ve never actually used one of these boards before, so I’m not positive what the problem could be. I DO know that each socket for the EPROMs are sized for 2MB. You’re using the 016, so you’re doing it right there.

      I haven’t encountered any problems like you’re experiencing – my games either work, or don’t turn on at all. It’s strange that you’re getting it to work on an 033 but it freezes on two 016s.

      I’m honestly not sure what to tell you! Maybe try different 016’s or check to make sure there aren’t any cold solder joints anywhere? Maybe you’re getting an intermittent connection on one of the pins. I’m sorry I can’t be of more help but I think you’ve wired it all correctly!

      Like

    • what´s your native language? I am Brazilian. I had a problem similar to yours.
      what I did was to test a shvc-2a3m board for example and to map the tracks and saw that there is difference between the boards. So I made a jumper with a wire and it worked perfectly
      I do not remember exactly what the difference is

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    • You sure that your SRAM is compatible? It’s PCB code is 1A3M (3 is the size of its capacity – 32).
      P.S.: Sorry my bad english, I’ve learned from myself.

      Like

      • Alguém pode me ajudar já faço repro só que em memória 27c801 queria fazer alguns jogos de RPG traduzidos para PT BR em memória 29F033 mas não estou conseguindo preparar a ROM para poder gravar na memória que mencionei
        Alguém poderia me ajudar ?

        Like

    • Ola Aldueaco. Você conseguiu resolver seu problema? Eu também estou tentando fazer um cartucho repro utilizando essa mesma PCB (SHVC-BA3M-20), mas como uma das mask rom é de 36 pinos o meu não deu certo. Estou utilizando uma eprom m27c801.

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    • does a shvc-ba3m-20 accept 2x16mb rom chips? these boards were designed to use a 16+8=24 typically used for super metroid.
      I asked a similar question regarding useing these boards as donors but never got a reponse

      Like

  2. Hi everyone and thx for replying my post, I´m mexican, I found that board shvc-ba3m-20 pin 2 and 35 are connected between them in both chips placement of the board, I tried to cut traces and brigde them to the correct place using wires, like the board i used for 29f033, but i couldn´t make it work, may be there is another difference that i can not find,anyways i used a 29f033 for my repro and complicate myself, greetings

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  3. Boa tarde sei que tem brasileiros aqui na página se alguém poder me ajudar estou parado na preparação da ROM para poder gravar na 29F033 alguém poderia me ajudar desde já agradeço

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  4. I noticed that the ROM images themselves have a NTSC or PAL indicator. Can I only use a NTSC rom on an NTSC machine? If the CIC is what makes this determination than I would think it wouldn’t matter yet my own project seems to refuse to boot and the only variable I can think of is the PAL ROM that is being used.

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  5. Does anyone know how to convert a SHVC-BA3M board to use as a repro with a 32mb or 16mb buyic adaptor board or a m27c801? I have a few of these and would like to make anything out if them

    Mmmonkets had a similar guide on how to convert a mother cart using a SHVC-BA3M which I used for chrono trigger repro. I would assume something solar could be done on a ba3m???

    Like

    • Does anyone know how to convert a SHVC-BA3M board to use as a repro with a 32mb or 16mb buyic adaptor board or a m27c801? I have a few of these and would like to make anything out of them

      Mmmonkey had a similar guide on how to convert a mother cart using a SHVC-BJ3M which I used for chrono trigger repro. I would assume something solar could be done on a ba3m???

      Like

      • So I just realized that WordPress hasn’t been sending me emails for when people comment. Sorry! I probably missed your earlier comment. I gotta take some time and look through all the ones I missed.

        Anyway, I don’t have a BA3M or BJ3M board to mess around with, but I think that if it has two slots for 16 Mbit EPROMs you should be fine replacing them with the same size. But I can’t say for sure. I didn’t do a lot on these boards because they’re more uncommon and since writing the donor guide I’ve moved on to using my own PC boards instead.

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