diff --git a/src/mess/includes/bbc.h b/src/mess/includes/bbc.h
index b386e9670d0..96200e8ca3c 100644
--- a/src/mess/includes/bbc.h
+++ b/src/mess/includes/bbc.h
@@ -161,10 +161,10 @@ public:
 	int m_len3;
 	int m_mc6850_clock;
 	UINT8 m_serproc_data;
-	int m_dcd;
-	int m_rxd;
-	int m_txd;
-	int m_cts;
+	int m_dcd_cass;
+	int m_rxd_cass;
+	int m_rxd_rs423;
+	int m_cts_rs423;
 	UINT32 m_nr_high_tones;
 	emu_timer *m_tape_timer;
 
@@ -327,9 +327,9 @@ public:
 	DECLARE_WRITE_LINE_MEMBER(bbc_wd177x_intrq_w);
 	DECLARE_WRITE_LINE_MEMBER(bbc_wd177x_drq_w);
 	DECLARE_WRITE_LINE_MEMBER(bbc_vsync);
-	DECLARE_READ_LINE_MEMBER(bbc_rxd_r) { return m_rxd; }
-	DECLARE_READ_LINE_MEMBER(bbc_dcd_r) { return m_dcd; }
-	DECLARE_READ_LINE_MEMBER(bbc_cts_r) { return m_cts; }
+	DECLARE_READ_LINE_MEMBER(bbc_rxd_r) { return ( m_serproc_data & 0x40 ) ? m_rxd_rs423 : m_rxd_cass; }
+	DECLARE_READ_LINE_MEMBER(bbc_dcd_r) { return ( m_serproc_data & 0x40 ) ? 0 : m_dcd_cass; }
+	DECLARE_READ_LINE_MEMBER(bbc_cts_r) { return ( m_serproc_data & 0x40 ) ? m_cts_rs423 : 1; }
 
 	DECLARE_DEVICE_IMAGE_LOAD_MEMBER( bbcb_cart );
 
diff --git a/src/mess/machine/bbc.c b/src/mess/machine/bbc.c
index 519659f2d69..0a82e3ed995 100644
--- a/src/mess/machine/bbc.c
+++ b/src/mess/machine/bbc.c
@@ -1292,7 +1292,7 @@ const uPD7002_interface bbc_uPD7002 =
 
 void bbc_state::MC6850_Receive_Clock(int new_clock)
 {
-	m_rxd = new_clock;
+	m_rxd_cass = new_clock;
 
 	//
 	// Somehow the "serial processor" generates 16 clock signals towards
@@ -1317,7 +1317,7 @@ TIMER_CALLBACK_MEMBER(bbc_state::bbc_tape_timer_cb)
 			//this is to long to recive anything so reset the serial IC. This is a hack, this should be done as a timer in the MC6850 code.
 			logerror ("Cassette length %d\n",m_wav_len);
 			m_nr_high_tones = 0;
-			m_dcd = 0;
+			m_dcd_cass = 0;
 			m_len0=0;
 			m_len1=0;
 			m_len2=0;
@@ -1339,7 +1339,7 @@ TIMER_CALLBACK_MEMBER(bbc_state::bbc_tape_timer_cb)
 			/* Clock a 0 onto the serial line */
 			logerror("Serial value 0\n");
 			m_nr_high_tones = 0;
-			m_dcd = 0;
+			m_dcd_cass = 0;
 			MC6850_Receive_Clock(0);
 			m_len0=0;
 			m_len1=0;
@@ -1354,7 +1354,7 @@ TIMER_CALLBACK_MEMBER(bbc_state::bbc_tape_timer_cb)
 			m_nr_high_tones++;
 			if ( m_nr_high_tones > 100 )
 			{
-				m_dcd = 1;
+				m_dcd_cass = 1;
 			}
 			MC6850_Receive_Clock(1);
 			m_len0=0;
@@ -1987,10 +1987,10 @@ DEVICE_IMAGE_LOAD_MEMBER( bbc_state, bbcb_cart )
 DRIVER_INIT_MEMBER(bbc_state,bbc)
 {
 	m_Master=0;
-	m_rxd = 0;
-	m_dcd = 0;
-	m_txd = 0;
-	m_cts = 1;
+	m_rxd_cass = 0;
+	m_rxd_rs423 = 0;
+	m_dcd_cass = 0;
+	m_cts_rs423 = 1;
 	m_nr_high_tones = 0;
 	m_serproc_data = 0;
 	m_tape_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(bbc_state::bbc_tape_timer_cb),this));
@@ -1999,10 +1999,10 @@ DRIVER_INIT_MEMBER(bbc_state,bbc)
 DRIVER_INIT_MEMBER(bbc_state,bbcm)
 {
 	m_Master=1;
-	m_rxd = 0;
-	m_dcd = 0;
-	m_txd = 0;
-	m_cts = 1;
+	m_rxd_cass = 0;
+	m_rxd_rs423 = 0;
+	m_dcd_cass = 0;
+	m_cts_rs423 = 1;
 	m_nr_high_tones = 0;
 	m_serproc_data = 0;
 	m_tape_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(bbc_state::bbc_tape_timer_cb),this));