オーディオ

DSは16個のサウンドチャネルを持ってるらしいです。 サスペンド状態から復帰時、15ミリ秒は音を鳴らしてはいけないそうです。

   * Sampled Channels
   * Synth Channels?
   * Microphone 

(ARM7 only) Address Name 0x04000504:16 SOUND_BIAS

SOUND_BIAS is just a 16 bit? bias value. The BIOS function that adjusts it does so slowly (delay between each adjustment up or down), and only to two targets (0 and 0x200.) I can manually set it from 0x000 to 0x3FF, but there is an audible click when changing it fast.

Seemingly audio related, but pretty much unknown regs so far: Address ffff 0000 Name 0x040004?0:16 837f 0000 ? 0x040004?2:16 ff7f 0000 ? 0x040004?8:16 write-only? channel(r0).hw8 = 0x10000 - r1 in metroid

? ranges from 0x0 to 0xF, smells like 16 channels Address ffff 0000 Name 0x04000500:16 bf7f 0000 ? 0x04000508:16 8f8f 0000 ? 0x04000510:32 07fffffc 0000 ? 0x04000518:32 07fffffc 0000 ?

508:16, b7 is tested

SoundRelated1 sets the low 4 bits for either 508 or 509 (as a byte), based on 4 seperate input parameters, 508 is related to 510, and 509 to 518 (channel<<0 and channel<<3)

Dunno if these are sound either, but the BIAS register is right here.