[NES II] Move switches to $f000-$ffff

JMarlin / nesii

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[NES II] Move switches to $f000-$ffff #36

Closed JMarlin closed 5 days ago

JMarlin commented 1 week ago

Depends on prior completion of #34 Intent is to cause reads to $fxxx range to return ROM content and writes to $fxxx range to set mode switches to free up more space for cart RAM

JMarlin commented 6 days ago

Need to remember to:

[x] Update PLD
[x] Update MARIO
[x] Update DONKEY
[x] Update any switch constants in bios and NOS

JMarlin commented 6 days ago

Alright, this is the one that's going to be super hinky, which doesn't surprise me at all. If I keep the switches at $d000, we boot fine (though of course running an NES game just boots back to the bios entry) If I move them to $f000, the bios doesn't boot at all. I assume this is because the switches are getting randomly written as the CPU attempts to read the ROM.

Might need some hardware debugging or patches, but first I think I need to just experiment with maybe making the logic the exact same between the ROM select and the switch select except for write polarity first.

JMarlin commented 5 days ago

Welp, making the switch and romsel expressions the same but with inverted RWB did not improve the situation. No boot. Grey screen.

JMarlin commented 5 days ago

lol, nevermind. Doing what I described in the last comment worked perfectly fine, I just forgot to upload the bios image to the ROM emulator. Nice.

JMarlin commented 5 days ago

Reopening, because MARIO looks like it's perhaps hitting some corruption. Probably the switches getting flipped when in game mode, so we might still need a small tweak there.

JMarlin commented 5 days ago

Re-closing, because the above looks like a fluke or maybe the thing straight-up wasn't crashed and I just misapprehended the situation. Ran MARIO and DONKEY each for about an hour and they didn't have any issues at all.