diff --git a/Source/HBIOS/cfg_sbc.asm b/Source/HBIOS/cfg_sbc.asm
index 05fb656b..25e3c142 100644
--- a/Source/HBIOS/cfg_sbc.asm
+++ b/Source/HBIOS/cfg_sbc.asm
@@ -25,19 +25,22 @@ UARTENABLE	.EQU	TRUE		; TRUE FOR UART SUPPORT (ALMOST ALWAYS WANT THIS TO BE TRU
 UARTOSC		.EQU	1843200		; UART OSC FREQUENCY
 ACIAENABLE	.EQU	FALSE		; TRUE FOR MOTOROLA 6850 ACIA SUPPORT
 ;
-SIOENABLE	.EQU	TRUE		; TRUE FOR ZILOG SIO SUPPORT						;PS 
-SIOMODE		.EQU	SIOMODE_ZP	; SIOMODE_RC, SIOMODE_SMB, SIOMODE_ZP					;PS
-DEFSIOACFG	.EQU	SER_9600_8N1	; DEFAULT SERIAL LINE CONFIG						;PS
-DEFSIOBCFG	.EQU	SER_9600_8N1	; DEFAULT SERIAL LINE CONFIG						;PS
-DEFSIODIV	.EQU	8		; 1=RC2014, SMB, 2/4/8/16/32/64/128/256 for ZP depending on jumper X5	;PS
-DEFSIOCLK	.EQU	4915200		; 2457600/4915200=ZP,7372800=RC/SMB - SIO FIXED OSC FREQUENCY		;PS
-SIODEBUG	.EQU	TRUE		;PS
+SIOENABLE	.EQU	FALSE		; TRUE FOR ZILOG SIO SUPPORT
+SIOMODE		.EQU	SIOMODE_ZP	; SIOMODE_RC, SIOMODE_SMB, SIOMODE_ZP
+DEFSIOACFG	.EQU	SER_9600_8N1	; DEFAULT SERIAL LINE CONFIG
+DEFSIOBCFG	.EQU	SER_9600_8N1	; DEFAULT SERIAL LINE CONFIG
+DEFSIODIV	.EQU	8		; 1=RC2014, SMB, 2/4/8/16/32/64/128/256 for ZP depending on jumper X5
+DEFSIOCLK	.EQU	4915200		; 2457600/4915200=ZP,7372800=RC/SMB - SIO FIXED OSC FREQUENCY
+SIODEBUG	.EQU	FALSE		;
 ;
 VDUENABLE	.EQU	FALSE		; TRUE FOR VDU BOARD SUPPORT
 CVDUENABLE	.EQU	FALSE		; TRUE FOR CVDU BOARD SUPPORT
 NECENABLE	.EQU	FALSE		; TRUE FOR uPD7220 BOARD SUPPORT
 TMSENABLE	.EQU	FALSE		; TRUE FOR N8 (TMS9918) VIDEO/KBD SUPPORT
 VGAENABLE	.EQU	FALSE		; TRUE FOR VGA VIDEO/KBD SUPPORT
+SNDENABLE	.EQU	TRUE		; TRUE FOR PSG OR IOBIT SOUND
+CONBELL		.EQU	CONBELL_PSG ; CONBELL_IOBIT / CONBELL_PSG
+
 ;
 MDENABLE	.EQU	TRUE		; TRUE FOR ROM/RAM DISK SUPPORT (ALMOST ALWAYS WANT THIS ENABLED)
 MDTRACE		.EQU	1		; 0=SILENT, 1=ERRORS, 2=EVERYTHING (ONLY RELEVANT IF MDENABLE = TRUE)