Sunday, March 06, 2005


Things are going rather well with the NMK004 simulation.

The NMK004 state machine supports:

  1. Six FM channels; each pair of them shares one of the three YM2203 voices.
  2. Three PSG channels, each one using one of the PSG voices of the YM2203.
  3. Eight Effects channels, which can use the total eight voices provided by the two Oki M6295 to play sample-based sounds like drums (but they are also sometimes used to play effects not music related).
  4. Direct triggering of Oki M6295 samples (this is not strictly part of the state machine)

Current simulation status is as follows:

  1. Not done yet.
  2. Partially done. The state machine works and seems to play notes at the correct speed. However, the pitch of the notes is way off.
  3. Seems to be ok.
  4. Is mostly ok but there are some strange things here and there - difficult to say if it's a simulation error or just how it's supposed to be.

I am growing more and more convinced that the internal ROM of the NMK004 is the same in all games. A few of the games in the driver have additional protection issues, but at this point I don't think they are related to the NMK004.

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