diff --git a/Source/HBIOS/cfg_rcez80.asm b/Source/HBIOS/cfg_rcez80.asm
index 0b89a9e9..f18df695 100644
--- a/Source/HBIOS/cfg_rcez80.asm
+++ b/Source/HBIOS/cfg_rcez80.asm
@@ -132,6 +132,7 @@ BQRTC_BASE	.EQU	$50		; BQRTC: I/O BASE ADDRESS
 ;
 EZ80RTCENABLE	.EQU	TRUE		; EZ80 ON CHIP RTC
 ;
+EZ80TMR_NONE	.EQU	0		; DO NOT USE ON-BOARD TIMER TO GENERATE TICKS
 EZ80TMR_INT	.EQU	1		; MARSHALL TIMER TICK INTERRUPTS FROM EZ80 TO HBIOS
 EZ80TMR_FIRM	.EQU	2		; DELEGATE SYS TIMER HBIOS CALL TO EZ80 FIRMWARE (TIMER TICK INTS DISABLED)
 EZ80TIMER	.EQU	EZ80TMR_INT	; EZ80: TIMER TICK MODEL: EZ80TMR_[INT|FIRM]
diff --git a/Source/HBIOS/ez80systmr.asm b/Source/HBIOS/ez80systmr.asm
index 580ba4a1..00f1b6f6 100644
--- a/Source/HBIOS/ez80systmr.asm
+++ b/Source/HBIOS/ez80systmr.asm
@@ -29,7 +29,8 @@ EZ80_TMR_INT:
 	CALL	HB_TIMINT		; RETURN NZ - HANDLED
 	OR	$FF
 	RET
-#ELSE
+#ENDIF
+#IF (EZ80TIMER == EZ80TMR_FIRM)
 
 EZ80_TMR_INIT:
 	CALL	NEWLINE			; FORMATTING
@@ -79,3 +80,7 @@ SYS_SETSECS:
 	RET
 
 #ENDIF
+#IF (EZ80TIMER == EZ80TMR_NONE)
+EZ80_TMR_INIT:
+	RET
+#ENDIF