Update ay38910.asm

- Exception for NABU in PSG initialization

Source/HBIOS/ay38910.asm

@@ -278,8 +278,14 @@ AY_TIMTIK	.DB	0		; COUNT DOWN TO FINISH BOOT BEEP
 ;======================================================================
 ;
 AY_INIT:
+#IF (AYMODE == AYMODE_NABU)
+	; I/O B=INPUT, I/O A=OUTPUT, NOISE CHANNEL C, B, A DISABLE, TONE CHANNEL C, B, A ENABLE
+	LD	DE,(AY_R7ENAB*256)+$78	; SET MIXER CONTROL / IO ENABLE.  $78 - 01 111 000
+#ELSE
+	; I/O PORTS = OUTPUT, NOISE CHANNEL C, B, A DISABLE, TONE CHANNEL C, B, A ENABLE
 	LD	DE,(AY_R7ENAB*256)+$F8	; SET MIXER CONTROL / IO ENABLE.  $F8 - 11 111 000
-	JP	AY_WRTPSG		; I/O PORTS = OUTPUT, NOISE CHANNEL C, B, A DISABLE, TONE CHANNEL C, B, A ENABLE
+#ENDIF
+	JP	AY_WRTPSG		
 ;
 AY_CHKREDY:
 	LD	A, (AY_READY)