NES MMC5 Demo

A demo to test and show features that could be integrated in a NES game using the MMC5 chip.

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Compile

make

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Run

make run_a

Important: Because this demo use more than 32K of PRG RAM and none of the ExROM boards was made with this amount of RAM, Some emulator may not be able to run the demo. The game will stop and blink red if it cannot access more than 32K of RAM.

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FCEUX emulator

FCEUX can natively emulate a MMC5 with more than 32K of RAM and will run the demo without problems.

FCEUX download link: https://fceux.com/web/download.html

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Mesen emulator

If you want to use Mesen for his debugging capability. You can still use it by "making some modification". For this, you will need to:

1. Download the source of Mesen-X (fork of Mesen and most up-to-date version that I am aware of): https://github.com/NovaSquirrel/Mesen-X

2. Follow the instruction on how to compile Mesen: https://github.com/NovaSquirrel/Mesen-X/blob/master/COMPILING.md

3. Change some lines of code in the file named "MMC5.h" located in the "Core" folder:

   • Change line 80 from:

     bankNumber &= 0x07;

     to:

     bankNumber &= 0x0F;

   • Change around line 100 from:

     if(realSaveRamSize + realWorkRamSize != 0x4000 && bankNumber >= 4) {
         //When not 2x 8kb (=16kb), banks 4/5/6/7 select the empty socket and return open bus
         accessType = MemoryAccessType::NoAccess;
     }

     to:

     // if(realSaveRamSize + realWorkRamSize != 0x4000 && bankNumber >= 4) {
     //  //When not 2x 8kb (=16kb), banks 4/5/6/7 select the empty socket and return open bus
     //  accessType = MemoryAccessType::NoAccess;
     // }

4. Recompile Mesen and if everything was done correctly, the demo should not blink red anymore and start normally.