This is the routine that plays a SFX;
This routine is used for the in game sound fx (like shooting) <<<<<<<<<<<<

In SCC-BLAFFER I use ONLY channel 3 for PSG (drums) channel 1 and 2 are unused.
What do I need to change in the routine below to let it leave channel 3 untouched ?

;+----- Set all PSG regs.-----+ ;SEE (Sound Effects Editor)
SETPSG: 
	LD IX,PSGREG
	LD E,0		;Start reg.0
	INC HL		;[skip event byte]

;

	LD B,3 		;First 6 reg. [sound frequency]
STPS.0: PUSH BC
	LD C,(HL)	;reg. $00, $02 or $04		-> Fine tune : A,B & C channels
	INC HL
	LD B,(HL)	;reg. $01, $03 or $05		-> Coarse tune : A,B & C channels
	BIT 7,(HL)	;check and handle Tuning
	CALL NZ,TUNWUP
	BIT 6,(HL)
	CALL NZ,TUNWDW
	INC HL
	LD A,C
	CALL WRTPSG
	LD A,B
	AND $0F
	CALL WRTPSG
	POP BC
	DJNZ STPS.0

	LD A,(HL)	;reg. $06 [Rustle frequency]       -> Noise channel ?
	INC HL
	BIT 7,A
	CALL NZ,TUN_UP
	BIT 6,A
	CALL NZ,TUN_DW
	AND $1F
	CALL WRTPSG

	LD A,(HL)	;reg. $07 [set channel ON/OFF]       ->Mixer :/EN noise /EN A /EN B /EN C 
	AND $3F
	OR $80		;set bit 7 is necessary to write the PSG!! ---> pour SSG/YM2610 : idem ??? pas sur !
	INC HL
	CALL WRTPSG

	LD B,3		;reg.  $08-$0A [Volume  Channels A,B & C]
STPS.1: PUSH BC
	LD A,(HL)
	INC HL
	BIT 5,A
	JP NZ,STPS.2	;Volume pattern is set.
	LD C,A
	AND $0F
	BIT 7,C
	CALL NZ,TUN_UP
	BIT 6,C
	CALL NZ,VOL_DW
	CALL FIXVOL	; 						Volume est paramétrable !!
STPS.2: AND $1F
	CALL WRTPSG
	POP BC
	DJNZ STPS.1

	LD B,3		; reg $0B-$0D [volume effect] ->Volume envelope period fine tune/coarse tune & Volume envelop shape
STPS_2: LD A,(HL)
	INC HL
	CALL WRTPSG
	DJNZ STPS_2
	RET


; Tuning
;- byte
TUN_UP: ADD A,(IX)	; Up
	RET
TUN_DW: SUB (IX)	; Down
	NEG
	RET
;- word
TUNWUP: PUSH HL
	LD L,(IX)
	LD H,(IX+1)
	ADD HL,BC
	PUSH HL
	POP BC
	POP HL
	RET
TUNWDW: PUSH HL
	LD L,(IX)
	LD H,(IX+1)
	XOR A
	SBC HL,BC
	PUSH HL
	POP BC
	POP HL
	RET

; Volume Down
VOL_DW: AND $0F
	LD B,A
	LD A,(IX+0)
	SUB B
	RET NC
	XOR A
	RET


; Make relative volume (depending on "SEEVOL"
; In: A, volume
; Out: A, new volume [seevol - (15-volume)]
FIXVOL: AND $0F
	LD B,A
	LD A,15
	SUB B
	LD C,A
	LD A,(SEEVOL)
	AND $0F
	SUB C
	RET NC
	XOR A
	RET


; Write PSG (not ROM-BIOS compatible!)
; In: A, data
; E, port
; IX, PSG store table
; Out: E+1
; IX+1
WRTPSG: LD (IX),A
	INC IX
	PUSH AF
	LD A,E
	OUT ($A0),A		; pour MSX /port $A0(write) register Write port -> A modifier NEOGEO :OUT ($4),A
	INC E
	POP AF
	OUT ($A1),A		; pour MSX /port $A1(write) Value Write port	-> A modifier NEOGEO :OUT ($5),A
	RET


;+----------------------------< Work Area >------------------------------------+
; reg. 0 1 2 3 4 5 6 7 8 9 A B C D
PSGREG: DB 0,0,0,0,0,0,0,0,0,0,0,0,0,0 ; - PSG port store buffer -