diff --git a/src/mame/drivers/hanaawas.cpp b/src/mame/drivers/hanaawas.cpp
index d361c395be4..843ad3bd9e6 100644
--- a/src/mame/drivers/hanaawas.cpp
+++ b/src/mame/drivers/hanaawas.cpp
@@ -90,7 +90,7 @@ ADDRESS_MAP_END
 static ADDRESS_MAP_START( io_map, AS_IO, 8, hanaawas_state )
 	ADDRESS_MAP_GLOBAL_MASK(0xff)
 	AM_RANGE(0x00, 0x00) AM_READWRITE(hanaawas_input_port_0_r, hanaawas_inputs_mux_w)
-	AM_RANGE(0x01, 0x01) AM_READNOP /* it must return 0 */
+	AM_RANGE(0x01, 0x01) AM_READNOP /* r bit 1: status ready, presumably of the input mux device / w = configure device? */
 	AM_RANGE(0x10, 0x10) AM_DEVREAD("aysnd", ay8910_device, data_r)
 	AM_RANGE(0x10, 0x11) AM_DEVWRITE("aysnd", ay8910_device, address_data_w)
 	AM_RANGE(0xc0, 0xc0) AM_WRITENOP // watchdog