Everdrive N8/N8 Pro Expansion Audio and Mapper Bugs/inaccuracies
- Bus conflicts don't work, anything relating to the hardware relying on it just doesn't function correctly.
- Features not used/rarely used are often unimplemented/not working, each chip will have it's own extra detail on what does and doesn't work.
- Mostly accurate, up until you distort the sawtooth wave using the extra volume capabilities.
- Most pulse waves seem to be off by around 1-2%.
- Modulation is broken, sometimes it tries to work, but doesn't.
- Lowpass isn't emulated.
- FDS BIOS uses a special custom BIOS instead, which doesn't work with some unlicensed titles (namely the Super PIG games)
- Other sound modes (noise, envelope) don't work and as such, can't be combined with others to make different sounds. Using values to mix tone and one of the other two features or using an unused feature by itself produces nothing.
- Analogue output isn't emulated, but it is approximated, by sampling the 5B squares at a ridiculous 50 MHz. (50 000 000 Hz, more than the 96 000 Hz or 44 100 Hz of most .wav files)
- Pulses are not inverted.
- PCM is missing the eighth bit, making it essentially a clone of the 7-bit PCM feature of the stock 2A03.
- Patches use approximations of the real chip, so anything using the expansion audio doesn't work by default.
- Custom patches suffer from high feedback.
- Multiplexer hiss from 5+ channels isn't present.
- Wave sizes past 32 aren't supported.
- Proprietary PCM chips do not work.
- N8 Pro spams $00 writes to DPCM, leading to lots and lots of DPCM bugs.