NEW_TUNE         EQU 1; data=tune number
NEW_FX           EQU 2; data=effect number 
FADE             EQU 3; see below 
CLR_FLAG         EQU 6; data=flag number 
TUNE_VOL         EQU 7; data=volume of tune (see below) 
FX_VOL           EQU 8; data=volume of effect (see below) 
SET_FLAG         EQU 11; data=flag number 
 
To execute a command: load the high byte of the accumulator 
with the command number and the low byte with the data.
  
I.E.  ; To play the first tune
                 LDA #256*NEW_TUNE+1 
                 JSL put_fifo  ; To play the second do  
                 LDA #256*NEW_TUNE+2 
                 JSL put_fifo  ; Note Starting tune 0 will stop the current tune.  
To play the first Sound Effect
                 LDA #256*NEW_FX+0 
                 JSL put_fifo  

NOTE: Sound Effect 0 is used by the speech and so your effects start at 1.  

FADE; The data for the fade command is as follows.  
$FF = slow fade down ; 
$fE = slightly faster fade down 
$01 = slow fade up
$02 = slightly faster fade up ; and so on 
Sorry I couldn't be more descriptive with this, but it is a matter of 
playing around until its right.  

TUNE_VOL and FX_VOL  ; Tune volume sets the volume of the currently playing tune.
(We tend to use this to fade music now) 

Effect volume sets the volume that the NEXT sound effect 
will be played at. (Values are 0 to $7F)