+extern inline void unchime_start() { unchime_count = CHIME_TIME; }
+extern inline void chime_for(u8 time) { chime_count = time; }
+extern inline void unchime_for(u8 time) { unchime_count = time; }
+
+void chime(); /* RTI interrupt */
+
+/* internal helpers, also could be called from outside world */
+extern inline void chime_on() { bset((void*)&_io_ports[M6811_PORTA], PORTA_CHIME); }
+extern inline void chime_off() { bclr((void*)&_io_ports[M6811_PORTA], PORTA_CHIME);}