Gameboy 4MB 32KB FRAM MBC3 with RTC Flash Cart (Build it yourself or pre-assembled)


Usually MBC3 chips only allow for 2MB of flash however by adding a special logic chip, we can extend the flash size to 4MB so you can future proof your RTC cart. There is an MBC30 chip which does support 4MB but carts usually go for $12-18 and aren’t very common where as MBC3 carts go for $1-3 and are everywhere. Re-flashable with any flasher like GBxCart RW that supports the MBM29F033C chip via the audio pin method.

As most users build MBC3 carts themselves, we’re providing this option so please ensure you know how to solder and you will need to source all the parts yourself (check the list below) and we will only provide the PCB and special logic chip (unsoldered).

SKU: N/A Category:


Build it yourself parts required:
MBC3 chip (take from an MBC3 cart)
MBC3 8 pin power management chip (take from an MBC3 cart)
4MB MBM29F033C Flash
CR2032 Battery holder + CR2032 battery
32.768 KHz crystal (take from an MBC3 cart)
300K resistor 0603 (take from an MBC3 cart)
2x 20pF capacitor 0603 (take from an MBC3 cart)
1K resistor (take from an MBC3 cart)
10K 0603 resistor
10K 0805 resistor
4x 0.1uF 0603

ROM: 4MB Flash (MBM29F033C)
FRAM: 32KB (Data retention of 20-50 years)
MBC: MBC3 original chip

The power consumption of MBC3 when powered from the battery appears to be around 2.3uA so a CR2032 should last around 7-10years.

The PCB finish is ENIG, Gold fingers (on the edge connector) with a 45 degree bevel to give the maximum life for insertion/removal of the cartridge.

If you will be installing this flash cart in an original shell, it is very difficult due to the CR2032 battery holder but it is possible.

Additional information

Weight 10 g
Build it yourself

Yes, I will only receive the PCB and special logic chip, Pre-assembled (includes battery and grey cartridge)

Flash carts

Gameboy carts, Low power, MBC3 support, RTC support, Saving supported


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