diff --git a/src/emu/bus/rs232/rs232.c b/src/emu/bus/rs232/rs232.c
index 304213750fe..eeff291621a 100644
--- a/src/emu/bus/rs232/rs232.c
+++ b/src/emu/bus/rs232/rs232.c
@@ -77,7 +77,13 @@ WRITE_LINE_MEMBER( rs232_port_device::write_dtr )
 WRITE_LINE_MEMBER( rs232_port_device::write_rts )
 {
 	if(m_dev)
-		return m_dev->input_rts(state);
+		m_dev->input_rts(state);
+}
+
+WRITE_LINE_MEMBER( rs232_port_device::write_etc )
+{
+	if(m_dev)
+		m_dev->input_etc(state);
 }
 
 device_rs232_port_interface::device_rs232_port_interface(const machine_config &mconfig, device_t &device)
diff --git a/src/emu/bus/rs232/rs232.h b/src/emu/bus/rs232/rs232.h
index 6337263c6ec..1a17d9b35d5 100644
--- a/src/emu/bus/rs232/rs232.h
+++ b/src/emu/bus/rs232/rs232.h
@@ -44,6 +44,7 @@ public:
 	DECLARE_WRITE_LINE_MEMBER( write_txd );
 	DECLARE_WRITE_LINE_MEMBER( write_dtr );
 	DECLARE_WRITE_LINE_MEMBER( write_rts );
+	DECLARE_WRITE_LINE_MEMBER( write_etc );
 
 	DECLARE_READ_LINE_MEMBER( rxd_r ) { return m_rxd; }
 	DECLARE_READ_LINE_MEMBER( dcd_r ) { return m_dcd; }
@@ -82,6 +83,7 @@ public:
 	virtual DECLARE_WRITE_LINE_MEMBER( input_txd ) {}
 	virtual DECLARE_WRITE_LINE_MEMBER( input_dtr ) {}
 	virtual DECLARE_WRITE_LINE_MEMBER( input_rts ) {}
+	virtual DECLARE_WRITE_LINE_MEMBER( input_etc ) {}
 
 	DECLARE_WRITE_LINE_MEMBER( output_rxd ) { m_port->m_rxd = state; m_port->m_rxd_handler(state); }
 	DECLARE_WRITE_LINE_MEMBER( output_dcd ) { m_port->m_dcd = state; m_port->m_dcd_handler(state); }
diff --git a/src/mess/drivers/cbm2.c b/src/mess/drivers/cbm2.c
index 72444cfd7fe..2fff94d2ba4 100644
--- a/src/mess/drivers/cbm2.c
+++ b/src/mess/drivers/cbm2.c
@@ -2142,6 +2142,9 @@ static MACHINE_CONFIG_START( p500_ntsc, p500_state )
 	MCFG_MOS6551_XTAL(XTAL_1_8432MHz)
 	MCFG_MOS6551_IRQ_HANDLER(DEVWRITELINE(MOS6525_1_TAG, tpi6525_device, i4_w))
 	MCFG_MOS6551_TXD_HANDLER(DEVWRITELINE(RS232_TAG, rs232_port_device, write_txd))
+	MCFG_MOS6551_DTR_HANDLER(DEVWRITELINE(RS232_TAG, rs232_port_device, write_dtr))
+	MCFG_MOS6551_RTS_HANDLER(DEVWRITELINE(RS232_TAG, rs232_port_device, write_rts))
+	MCFG_MOS6551_RXC_HANDLER(DEVWRITELINE(RS232_TAG, rs232_port_device, write_etc))
 
 	MCFG_MOS6526_ADD(MOS6526_TAG, XTAL_14_31818MHz/14, 60, DEVWRITELINE(MOS6525_1_TAG, tpi6525_device, i2_w))
 	MCFG_MOS6526_SERIAL_CALLBACKS(DEVWRITELINE(CBM2_USER_PORT_TAG, cbm2_user_port_device, cnt_w), DEVWRITELINE(CBM2_USER_PORT_TAG, cbm2_user_port_device, sp_w))