Hardware GBA Trying to figure out the capabilities of this repro cartridge

msdizzy · May 22, 2026

I'm trying to learn more about electronics by way of adapting repro cartridges. (I know, I should buy a flashcart instead. But I like individual cartridges and I learn stuff this way.)

At the moment I have one of these boards with an SRAM chip (namely the IS62C1024-70Q). I've been using a batteryless save patched game on it for a bit but I really don't like having to do that. I've heard that the extra writes are quite bad for the chip storing the ROM, but I'm not sure how much truth there is to that. Regardless, I'd really like to add a battery to this one and I'm trying to figure out if I can.

Here's the sheet for this chip: https://www.alldatasheet.com/datasheet-pdf/pdf/124475/ISSI/IS62C1024-70Q.html

According to it, I don't see a way for a battery to keep this powered, and I don't see a VBAT pin. And there doesn't appear to be any continuity between what I suspect to be the positive terminal for the would-be battery and the VCC pin which, from what I can see, is the only pin that can receive power.

Was what I found correct, or is adding a battery to this particular board doable? I thought about trying to get my hands of compatible FRAM chips that are also 32-pin, or looking for other 32-pin SRAM chips that are battery-backed.

Thank you all in advance!

master801 · May 27, 2026

Looks like if there was a battery, it would sit on U1 (ROM), since the pads near it are a dead giveaway.

You'd have to find someone with a similar repo cartridge that uses battery SRAM and reference to that. You can't just randomly throw components on and expect it to work since the FPGA or whatever they used wouldn't configure itself properly.

And honestly in my opinion, there's no point in doing this.

You're trying to mod a reproduction cartridge to effectively work worse than it originally did.

msdizzy · Monday at 2:55 AM

You can't just randomly throw components on and expect it to work since the FPGA or whatever they used wouldn't configure itself properly.

I am aware. That is precisely why I am here, asking you all.

And honestly in my opinion, there's no point in doing this. You're trying to mod a reproduction cartridge to effectively work worse than it originally did.

I am failing to see how? In its current state it cannot retain a save without a batteryless patched ROM. Adding a battery to allow the SRAM to function properly sounds like an improvement to me.

Jayro · Monday at 3:00 AM

You should post in Bennvenn's discord server, people in there are bootleg experts. This looks like a 16MB or 32MB ROM with SRAM, but lacking the extra components needed to add a battery. So you'll likely need a batteryless-patched ROM.

Apache Thunder · Monday at 3:02 AM

You'll likely need to swap D2's 0 ohm resistor bridge with a diode and install one in D1 as well. If the Gameboy repro PCB I have is anything to go by, this PCB likely isn't configured for having a battery. I'm sure the FPGA probably would know how to handle it already. The diodes are needed to prevent the battery from backfeeding the entire PCB instead of just the SRAM chip. Plus to prevent power from console reaching the battery. It's why my PCB has two diodes and yours likely does too.

As I recall my bootleg's PCB has an SRAM chip on it that lacks the battery and diodes/resistors. It's still used by the batteryless patched game though. The game patch was setup to flash the save to the flash the rom is stored on after the game saves to sram. So in my case I just needed to add the diodes and 10k resistor. Though in the end mine still didn't hold saves after power loss for more then a few seconds. maybe defective SRAM chip on mine that only holds saves during full power. It's a 5v sram chip but data sheet says it can retain a save down to 2v and my measurements of the power going to it show that it's getting almost 3v. Maybe mine doesn't need the resistor. Mine looks like this. this was before I installed the diodes and resistor FYI:

msdizzy · Monday at 3:04 AM

Jayro said:
You should post in Bennvenn's discord server, people in there are bootleg experts. This looks like a 16MB or 32MB ROM with SRAM, but lacking the extra components needed to add a battery. So you'll likely need a batteryless-patched ROM.

Thank you! I will poke around there!

Jayro · Monday at 3:06 AM

msdizzy said:
Thank you! I will poke around there!

Apache Thunder · Monday at 3:11 AM

Took an updated photo. My Gameboy bootleg PCB now currently looks like this. Maybe those folks over there could help me trouble shoot this one too perhaps?

I couldn't find SMD version of the diode this perticular board needs on Digikey so I ended up with larger threw hole ones. But I don't think that should be why mine isn't holding saves though. I checked and confirmed the diodes are doing their jobs correctly and that the SRAM chip was getting the minimum voltage required for data retention according to it's data sheet.

Maybe this PCB is just not designed to use a battery with 5v sram chips. I recall seeing a properly setup PCB use a 3.3v one. (the 5v/3.3v option bridges define what voltage the sram chip uses FYI. Mine is configured for 5v and since data sheet confirms this, I did not mess with that and left it as is.)

Jayro · Monday at 3:13 AM

Apache Thunder said:
Took an updated photo. My Gameboy bootleg PCB now currently looks like this. Maybe those folks over there could help me trouble shoot this one too perhaps?

View attachment 575880

I couldn't find SMD version of the diode this perticular board needs on Digikey so I ended up with larger threw hole ones. But I don't think that should be why mine isn't holding saves though. I checked and confirmed the diodes are doing their jobs correctly and that the SRAM chip was getting the minimum voltage required for data retention according to it's data sheet.

Oh definitely.

Apache Thunder · Monday at 3:16 AM

Can you link me to that Discord? I can try asking about mine there. Mine was a Pokemon Yellow bootleg I fell for.

I got a official GBxCart and have been able to reflash it. Bugs me that I can't get it to hold saves right now despite all the trouble adding the needed components. The seller who sold mine went through the trouble of putting a gamebit screw in the thing. Most bootlegs on ebay can easily be spotted via having triwing screws instead. So I thought that one might have been a real one.

I'd normally just return it due to being not as described but I didn't pay that much for it (sub 30 bucks if I recall) and this particular board can only be found on aliexpress so it's neat that I got one I didn't have to wait 3+ weeks for international shipping to get one.

Jayro · Monday at 4:37 AM

Apache Thunder said:
Can you link me to that Discord? I can try asking about mine there. Mine was a Pokemon Yellow bootleg I fell for.

I got a official GBxCart and have been able to reflash it. Bugs me that I can't get it to hold saves right now despite all the trouble adding the needed components. The seller who sold mine went through the trouble of putting a gamebit screw in the thing. Most bootlegs on ebay can easily be spotted via having triwing screws instead. So I thought that one might have been a real one.

I'd normally just return it due to being not as described but I didn't pay that much for it (sub 30 bucks if I recall) and this particular board can only be found on aliexpress so it's neat that I got one I didn't have to wait 3+ weeks for international shipping to get one.

https://discord.gg/Z3B2V8sq6

Hardware GBA Trying to figure out the capabilities of this repro cartridge

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