Update hbios.asm

Source/HBIOS/hbios.asm

@@ -1099,7 +1099,8 @@ Z280_BOOTERR	.TEXT	"\r\n\r\n*** Application mode boot not supported under Z280 n
 	XOR	A			; LED IS INVERTED, TURN IT ON
   #ENDIF
   #IF (LEDMODE == LEDMODE_RTC)
-	LD	A,%00000001		; LED 0
+	LD	A,(HB_RTCVAL)
+	OR	%00000001		; LED 0
 	LD	(HB_RTCVAL),A		; SAVE TO SHADOW REGISTER
   #ENDIF
 	OUT	(LEDPORT),A