I meant that the firmware itself is providing an API which is similar to the one of the A320.
I started to disassemble the NES emulator (which is actually
PocketNester) and found out that the functions used in the emulator are similar to the ones used in the SDK (some tiny differences) also i found these two functions, the first is run when the emulator starts and the second when it exits, maybe this have something to do with setting the CPU frequency :
printf("cpu set highest!\n"); PMSetMode(0x30,0);
printf("cpu set low!\n"): PMSetMode(0x20,0);
I haven't found how they're outputting the sound yet.