Pokemon Time Capsule

the conversion from hynix SRAM to FRAM on a Pokemon Yellow PCB

The precious Pokemon we spent hours capturing in the early nineties remain trapped, not just by pokeballs, but within a cartridge ravaged by time. Generally, Pokemon games before the GameBoy Advance era had SRAM and a small coin cell to save state as NVRAM (Non-volatile random access memory) was more expensive. These coin cells last 10-15 years, and many of the Pokemon games came out 20 years ago. [9943246367] decided to ditch the battery and swap the SRAM for a proper NVRAM on a Pokemon Yellow cartridge, 23 years later.

The magic that makes it work is a FRAM (ferroelectric random access memory) made by Cypress that is pin-compatible with the 256K SRAM (made by SK Hynix) on the original game cartridge PCB. While FRAM data will only last 10 years, it is a write-after-read process so as long as you load your save file every 10 years, you can keep your Pokemon going for decades. For stability, [9943246367] added a 10k pull-up on the inverted CE (chip enable) pin to make sure the FRAM is disabled when not in use. A quick test shows it works beautifully. Overall, a clever and easy to have to preserve your Pokemon properly.

Since you’re replacing the chip, you will lose the data if you haven’t already. Perhaps you can use [Selim’s] Pokemon Transporter to transport your pokemon safely from the SRAM to the FRAM.

17 thoughts on “Pokemon Time Capsule

    1. It really depends on the program. If they are only using it for storage then it will last “forever”. Sonic 3 clearly used it as plain old memory that could simply be written to which is why it wore out so quickly.

  1. I never played the game but if the is an explicit Save Game feature then an EEPROM would have been a better choice as I think GB games likely often access SRAM directly without any caching of any kind. FRAM is great but it wears in both read and write operations.

  2. @Matthew Carlson said: “The magic that makes it work is a FRAM (ferroelectric random access memory) made by Cypress that is pin-compatible with the 256K SRAM (made by SK Hynix) on the original game cartridge PCB.”

    On 17-April-2020 the American company Cypress Semiconductor Corporation was 100% bought-out by the German company Infineon Technologies AG for for $9.4 billion USD cash, a 55% premium over the then current market share price.[1][2] Another one bites the dust. This is what happens when governments recklessly print money out of thin air artificially driving interest rates down. With rock bottom interest rates Companies find it more profitable to go around buying-out competitors rather than investing in research and selling new products for a profit. Having so few competitors left in the Semiconductor Industry these days shuffling paper instead of building product is certainly exacerbating the forever chip shortage.

    1. Cypress Semiconductor Corporation


    2. Infineon Technologies – Cypress Semiconductor Acquisition


    1. Welcome to capitalism and free market economy; America’s greatest gift to the world..

      So why all the grief? Perhaps businessmen of Germany and other countries were simply good students, I guess? ;)
      Before our americanization, ‘we’ focused on ridiculous things like quality and customer friendliness.
      Then the US way of doing business teached ‘us’ to be hard and thinking economical.

  3. I’ve thought about doing this mod in old synths that will lose their custom patches and sequences once their batteries die, but without knowing the memory access patterns it’s always felt a bit risky. FRAM durability has improved, but if some location is read once every millisecond, it’s still not enough.

    What I would love to see is FRAM with integrated shadow SRAM – the SRAM would be initialized from the FRAM when the device is powered on, and used to serve read operations after that. Writes would go to both devices to maintain consistency.

      1. It seems their “EERAM” is only available with a serial interface, but I found products from Everspin Technologies (parallel MRAM) and Cypress (parallel nvSRAM) that claim unlimited endurance. Some of the Cypress chips even run off 5V, with the downside that they’re really expensive.

  4. Old Pokémon data can have a surprisingly high sentimental value. I figured that my old pokemans from Blue were long gone, until I recently went digging through my old N64 games and discovered that I’d transferred many of them to Pokémon Stadium, which does indeed have long-lasting flash memory. I had about a dozen of them on there – including the first one I ever caught. I could barely read when I first played that game. Those Pokémon are all old enough to drink.

    I was able to then extract each Pokemon’s data by using the hex viewer function built into my old GameShark, and typed up their hex data by hand to convert them into PkHex files (some helpful folks on the Project Pokémon discord helped me locate the correct start and stop points for each Pokémon).
    Now they’re securely backed up, and I even transferred a couple of them to newer games. Pretty cool.

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