The system command list includes tempo changes, fade in/out, stop playback, and more. The commands themselves are between $00-$1F, with a few reserved slots.
The current list is maintained in docs/functions/sound/soundCommands.txt, but replicated here in Markdown format (it may have changed; please check the text file for the latest):
$00 No Command
$01 Slot change
$02 Play eyecatch BGM (typically $5F)
$03 Soft reset
$04 Disable All (Music & Sounds)
$05 Disable Music
$06 Disable Sounds
$07 Enable All (Music & Sounds)
$08 Enable Music
$09 Enable Sounds
$0A Disable/Silence SSG (equiv. to SNK sound driver command $0F)
Part of the Sound Driver master todo list (#2)
The system command list includes tempo changes, fade in/out, stop playback, and more. The commands themselves are between
$00-$1F, with a few reserved slots.The current list is maintained in
docs/functions/sound/soundCommands.txt, but replicated here in Markdown format (it may have changed; please check the text file for the latest):$00No Command$01Slot change$02Play eyecatch BGM (typically$5F)$03Soft reset$04Disable All (Music & Sounds)$05Disable Music$06Disable Sounds$07Enable All (Music & Sounds)$08Enable Music$09Enable Sounds$0ADisable/Silence SSG (equiv. to SNK sound driver command$0F)$0BDisable/Silence FM$0CStop all ADPCM-A samples$0DStop ADPCM-B sample$0ETempo Change [1 arg;$00-$FF= 0-255bpm]$0F--currently unassigned--$10Fade Out [1 arg; speed$00-$FF]$11Stop Fade In/Out$12Fade In [1 arg; speed$00-$FF]$13--currently unassigned--$14--currently unassigned--$15--currently unassigned--$16--currently unassigned--$17--currently unassigned--$18--currently unassigned--$19--currently unassigned--$1A--currently unassigned--$1B--currently unassigned--$1C(Data Collect (Z80 -> 68K)?)$1D(Data Transfer (68K -> Z80)?)$1E--currently unassigned--$1F--currently unassigned--This list subject to change.