Hey everyone finally got around to making one of these and thought I would share how it is made.

Here is what you will need:
A 1A3M donor board
A 256k SRAM chip
A 32mbit TSOP chip
A switch with 3 leads

If you want to use the Reset button to switch between the games you can print up this board and use that instead of the switch.
http://nintendoage.com/forum/mess...

So lets get started.

Take your donor board and give it a test in the SNES to make sure it works.



Next de-solder the mask ROM and SRAM chips
The SRAM must be upgraded so that each game can save progress


Now lets prepare the ROM for programming.
The GoW and PW ROMs are 1.5MB so they need to be expanded with Lunar Expand to 2MB (16mbit)
Or you can just download the XDelta patch at the bottom of the thread, you can apply it to a stock LTTP and it will patch the ROM and expand it to 16mbit, there is one for GoW and PWR both have a patch for a ROM with and without a copier header.

Once you have both of your ROMs ready open a command console by holding the shift key and and selecting open command window here


Next use the copy command with the binary flag to merge the 2 files together


Once the ROM is ready, go ahead and program it to a TSOP chip and mount it to a TSOP to DIP board


I like to give mine a test run in a board that I put a ZIF socket on before soldering it to the donor board


Now lets get the SRAM ready, here is the pinout for the 64k original SRAM and the new 256k SRAM that will be going in the board


Now we need 128k SRAM because both games use 64k to save looking at the pinout we only need to lift pin 26.  Pin 1 can stay where it is, it will be connected to VCC and lock us to the upper half of the chip, this is fine because only 128k is needed anyway.
Now go ahead and bend up pin 26 on the SRAM, this will be connected to a switch to select between the 2 banks


Next you need to disconnect A21 on the mask ROM section so that it to can be conencted to the switch, I just followed the trace and made a cut in the PCB near one of the vias.


Now it is time to solder in the TSOP and SRAM, I started with the SRAM because it is shorter


Once you have both the TSOP and SRAM installed connect a wire to pin 26 on the SRAM and pin 2 on the TSOP adapter board


Then connect a wire to VCC and ground anywhere on the board


Now connect the 2 wires from the SRAM and the TSOP board to the center leg of the switch.  VCC and ground will connect to the outer legs.  This will force either all 0's or 1;s to these address lines and allow either game to load depending on where the switch is.


Now put it in the SNES and give it a test run, I made 3 saves to make sure that the SRAM was not being over wrote in the wrong spot on either game.


Then power off the SNES and flip the switch.

Awesome, thanks for doing this.

Aye sir, Thank you! This is awesome. Would this work for hirom titles as well?

I have a few 128K sram hirom SFC donors laying around I could use for something like this if so.

Is the SRAM off of a cart or was it bought separate?

This will work for HiROM games as long as you pick 2 that will fit on a single chip and expand them to 16mbit each.




Got it from mouser
http://www.mouser.com/Search/Prod...

If you want to use a player choice copy of Mario Paint that will work also as it has a 1A5M board.

Some of the Sim games use 256k SRAM but it is hit or miss on the 36 DIP support, best option is to upgrade a 1A3M board.

Hi Pete, very nice work, I was thinking about could this work with two 512Kb games in a 27c801? Or using 2MB with two 27c810?

If you have 2 games that are 512k then this will work. Just use the highest address line.

Not too sure how that would work with the swap bin though, you might need to just hand wire the 5 different wires.

Not families with the 27C810 chip but it should be the same process, just connect to the highest address line.

Yes, you have to join both 512kb roms in one single bin. Then apply swapbin and take the highest address a19 for bankswitching.

Looks like you are using wrapping wire and the protruding posts from the TSOP to DIP adapter are more than long enough to wrap to. I know it's only a couple connections, but it's cheap and is actually a better connection than solder (square posts cut into the wrapped wire and conduct better). Radio Shack doesn't have it anymore but I recently got a couple from eBay when I thought I lost my original.

It'll come in useful in other areas as well. I recently used it to repair a paging system with worn out conductive pads on the rubber membrane by disconnecting a ribbon cable and wire-wrapping switches to the header for the worn keys. I plugged the header back on to restore all the other keys and it worked perfectly.

Went ahead and did this. I combined Castlevania IV and Dracula X on one cart. No Sram was needed so I used a smaller more common lo rom board.

Pretty awesome.

Can I use other TSOP adapter? like I or III?

Don't see why it would not work, I think the 2 has some address lines mixed up though double check what line you are connecting the switch to

Hi, i tried this today and it work perfectly thank you.
Is it possible to do a Cartride with 4 Games (like Zelda Ancient Stone Tablet), without using a Super Metroid PCB?