diff --git a/src/emu/sound/sn76496.c b/src/emu/sound/sn76496.c
index 8ac32ae865a..47889acd5bf 100644
--- a/src/emu/sound/sn76496.c
+++ b/src/emu/sound/sn76496.c
@@ -202,7 +202,8 @@ void sn76496_base_device::device_start()
 
 READ_LINE_MEMBER( sn76496_base_device::ready_r )
 {
-	m_sound->update();
+	if (started())
+		m_sound->update();
 	return (m_cycles_to_ready > 0)? FALSE : TRUE;
 }
 
diff --git a/src/mess/drivers/mtx.c b/src/mess/drivers/mtx.c
index 2f10d111d64..d76219e8e67 100644
--- a/src/mess/drivers/mtx.c
+++ b/src/mess/drivers/mtx.c
@@ -379,6 +379,8 @@ static MACHINE_CONFIG_START( mtx512, mtx_state )
 	MCFG_CENTRONICS_PERROR_HANDLER(WRITELINE(mtx_state, write_centronics_perror))
 	MCFG_CENTRONICS_SELECT_HANDLER(WRITELINE(mtx_state, write_centronics_select))
 
+	MCFG_CENTRONICS_OUTPUT_LATCH_ADD("cent_data_out", "centronics")
+
 	MCFG_SNAPSHOT_ADD("snapshot", mtx_state, mtx, "mtx", 1)
 	MCFG_CASSETTE_ADD("cassette", mtx_cassette_interface)
 	MCFG_TIMER_DRIVER_ADD_PERIODIC("cassette_timer", mtx_state, cassette_tick, attotime::from_hz(44100))
diff --git a/src/mess/drivers/rmnimbus.c b/src/mess/drivers/rmnimbus.c
index 4e8bbac6d86..67bee16a053 100644
--- a/src/mess/drivers/rmnimbus.c
+++ b/src/mess/drivers/rmnimbus.c
@@ -333,6 +333,8 @@ static MACHINE_CONFIG_START( nimbus, rmnimbus_state )
 	MCFG_CENTRONICS_ADD(CENTRONICS_TAG, centronics_printers, "image")
 	MCFG_CENTRONICS_ACK_HANDLER(WRITELINE(rmnimbus_state, nimbus_ack_w))
 
+	MCFG_CENTRONICS_OUTPUT_LATCH_ADD("cent_data_out", "centronics")
+
 	/* sound hardware */
 	MCFG_SPEAKER_STANDARD_MONO(MONO_TAG)
 	MCFG_SOUND_ADD(AY8910_TAG, AY8910, 2000000)
diff --git a/src/mess/drivers/samcoupe.c b/src/mess/drivers/samcoupe.c
index d19f0c9a769..e8991d7588b 100644
--- a/src/mess/drivers/samcoupe.c
+++ b/src/mess/drivers/samcoupe.c
@@ -322,9 +322,9 @@ ADDRESS_MAP_END
 static ADDRESS_MAP_START( samcoupe_io, AS_IO, 8, samcoupe_state )
 	AM_RANGE(0x0080, 0x0081) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_WRITE(samcoupe_ext_mem_w)
 	AM_RANGE(0x00e0, 0x00e7) AM_MIRROR(0xff10) AM_MASK(0xffff) AM_READWRITE(samcoupe_disk_r, samcoupe_disk_w)
-	AM_RANGE(0x00e8, 0x00e8) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_DEVWRITE("lpt1_data", output_latch_device, write)
+	AM_RANGE(0x00e8, 0x00e8) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_DEVWRITE("lpt1_data_out", output_latch_device, write)
 	AM_RANGE(0x00e9, 0x00e9) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_READWRITE(samcoupe_lpt1_busy_r, samcoupe_lpt1_strobe_w)
-	AM_RANGE(0x00ea, 0x00ea) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_DEVWRITE("lpt2_data", output_latch_device, write)
+	AM_RANGE(0x00ea, 0x00ea) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_DEVWRITE("lpt2_data_out", output_latch_device, write)
 	AM_RANGE(0x00eb, 0x00eb) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_READWRITE(samcoupe_lpt2_busy_r, samcoupe_lpt2_strobe_w)
 	AM_RANGE(0x00f8, 0x00f8) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_READWRITE(samcoupe_pen_r, samcoupe_clut_w)
 	AM_RANGE(0x00f9, 0x00f9) AM_MIRROR(0xff00) AM_MASK(0xffff) AM_READWRITE(samcoupe_status_r, samcoupe_line_int_w)
@@ -557,9 +557,13 @@ static MACHINE_CONFIG_START( samcoupe, samcoupe_state )
 	MCFG_CENTRONICS_ADD("lpt1", centronics_printers, "image")
 	MCFG_CENTRONICS_BUSY_HANDLER(WRITELINE(samcoupe_state, write_lpt1_busy))
 
+	MCFG_CENTRONICS_OUTPUT_LATCH_ADD("lpt1_data_out", "lpt1")
+
 	MCFG_CENTRONICS_ADD("lpt2", centronics_printers, "image")
 	MCFG_CENTRONICS_BUSY_HANDLER(WRITELINE(samcoupe_state, write_lpt2_busy))
 
+	MCFG_CENTRONICS_OUTPUT_LATCH_ADD("lpt2_data_out", "lpt2")
+
 	MCFG_MSM6242_ADD("sambus_clock", samcoupe_rtc_intf)
 	MCFG_CASSETTE_ADD("cassette", samcoupe_cassette_interface)
 	MCFG_SOFTWARE_LIST_ADD("cass_list","samcoupe_cass")
diff --git a/src/mess/drivers/trs80.c b/src/mess/drivers/trs80.c
index 63ee07be23f..ec2db385717 100644
--- a/src/mess/drivers/trs80.c
+++ b/src/mess/drivers/trs80.c
@@ -627,6 +627,8 @@ static MACHINE_CONFIG_DERIVED( model1, trs80 )      // model I, level II
 
 	MCFG_DEVICE_ADD("cent_status_in", INPUT_BUFFER, 0)
 
+	MCFG_CENTRONICS_OUTPUT_LATCH_ADD("cent_data_out", "centronics")
+
 	MCFG_AY31015_ADD( "tr1602", trs80_ay31015_config )
 MACHINE_CONFIG_END
 
diff --git a/src/mess/drivers/tvc.c b/src/mess/drivers/tvc.c
index 42b7fb93927..2196ef5b2b1 100644
--- a/src/mess/drivers/tvc.c
+++ b/src/mess/drivers/tvc.c
@@ -705,6 +705,8 @@ static MACHINE_CONFIG_START( tvc, tvc_state )
 	MCFG_CENTRONICS_ADD(CENTRONICS_TAG, centronics_printers, "image")
 	MCFG_CENTRONICS_ACK_HANDLER(WRITELINE(tvc_state, tvc_centronics_ack))
 
+	MCFG_CENTRONICS_OUTPUT_LATCH_ADD("cent_data_out", "centronics")
+
 	/* cartridge */
 	MCFG_CARTSLOT_ADD("cart")
 	MCFG_CARTSLOT_EXTENSION_LIST("crt,rom,bin")