NS8250 Fixes [smf]

Loopback: tx goes high and data is clocked at the correct rate instead of appearing instantly
Modem status register: don't lose track of external signals when starting, resetting, switching loopback off, writing to register
Handshaking: active low for consistency (RS232 port now defaults handshaking lines high and serial mouse dtr/rts handling has been adjusted).

src/emu/bus/rs232/rs232.c

@@ -50,16 +50,16 @@ void rs232_port_device::device_start()
 	save_item(NAME(m_cts));
 
 	m_rxd = 1;
-	m_dcd = 0;
+	m_dcd = 1;
-	m_dsr = 0;
+	m_dsr = 1;
-	m_ri = 0;
+	m_ri = 1;
-	m_cts = 0;
+	m_cts = 1;
 
 	m_rxd_handler(1);
-	m_dcd_handler(0);
+	m_dcd_handler(1);
-	m_dsr_handler(0);
+	m_dsr_handler(1);
-	m_ri_handler(0);
+	m_ri_handler(1);
-	m_cts_handler(0);
+	m_cts_handler(1);
 }
 
 WRITE_LINE_MEMBER( rs232_port_device::write_txd )

src/emu/bus/rs232/ser_mouse.c

@@ -13,6 +13,8 @@ serial_mouse_device::serial_mouse_device(const machine_config &mconfig, device_t
 	: device_t(mconfig, type, name, tag, owner, clock, shortname, source),
 	device_rs232_port_interface(mconfig, *this),
 	device_serial_interface(mconfig, *this),
+	m_dtr(1),
+	m_rts(1),
 	m_x(*this, "ser_mouse_x"),
 	m_y(*this, "ser_mouse_y"),
 	m_btn(*this, "ser_mouse_btn")
@@ -23,7 +25,6 @@ const device_type MSFT_SERIAL_MOUSE = &device_creator<microsoft_mouse_device>;
 
 microsoft_mouse_device::microsoft_mouse_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
 	: serial_mouse_device(mconfig, MSFT_SERIAL_MOUSE, "Microsoft Serial Mouse", tag, owner, clock, "microsoft_mouse", __FILE__)
-	, m_dtr(0)
 {
 }
 
@@ -40,9 +41,18 @@ void serial_mouse_device::device_start()
 	m_enabled = false;
 	set_frame();
 	set_tra_rate(1200);
+	reset_mouse();
+
+	save_item(NAME(m_dtr));
+	save_item(NAME(m_rts));
+	save_item(NAME(m_queue));
+	save_item(NAME(m_head));
+	save_item(NAME(m_tail));
+	save_item(NAME(m_mb));
+	save_item(NAME(m_enabled));
 }
 
-void serial_mouse_device::device_reset()
+void serial_mouse_device::reset_mouse()
 {
 	m_head = m_tail = 0;
 	output_rxd(1);
@@ -202,24 +212,30 @@ void serial_mouse_device::set_mouse_enable(bool state)
 
 }
 
-void microsoft_mouse_device::check_state()
+
+WRITE_LINE_MEMBER(serial_mouse_device::input_dtr)
 {
-	if (m_dtr && m_rts)
+	m_dtr = state;
+	check_state();
+}
+
+WRITE_LINE_MEMBER(serial_mouse_device::input_rts)
+{
+	m_rts = state;
+	check_state();
+}
+
+WRITE_LINE_MEMBER(microsoft_mouse_device::input_rts)
+{
+	if (!m_dtr && m_rts && !state)
 	{
-		/* RTS toggled */
+		reset_mouse();
-		if (!m_old_rts && m_rts)
+		/* Identify as Microsoft 3 Button Mouse */
-		{
+		queue_data('M');
-			/* reset mouse */
+		queue_data('3');
-			serial_mouse_device::device_reset();
-			/* Identify as Microsoft 3 Button Mouse */
-			queue_data('M');
-			queue_data('3');
-		}
-		/* start a timer to scan the mouse input */
-		set_mouse_enable(true);
 	}
-	else
+
-		set_mouse_enable(false);
+	serial_mouse_device::input_rts(state);
 }
 
 

src/emu/bus/rs232/ser_mouse.h

@@ -21,7 +21,6 @@ public:
 
 protected:
 	virtual void device_start();
-	virtual void device_reset();
 	virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr);
 	virtual void mouse_trans(int dx, int dy, int nb, int mbc) = 0;
 	virtual void set_frame() = 0;
@@ -30,6 +29,13 @@ protected:
 	UINT8 unqueue_data() {UINT8 ret = m_queue[m_tail]; ++m_tail %= 256; return ret;}
 	virtual void tra_complete();
 	virtual void tra_callback();
+	void reset_mouse();
+
+	virtual WRITE_LINE_MEMBER(input_dtr);
+	virtual WRITE_LINE_MEMBER(input_rts);
+	int m_dtr;
+	int m_rts;
+
 private:
 	UINT8 m_queue[256];
 	UINT8 m_head, m_tail, m_mb;
@@ -40,25 +46,20 @@ private:
 	required_ioport m_x;
 	required_ioport m_y;
 	required_ioport m_btn;
+
+	void check_state() { set_mouse_enable(!m_dtr && !m_rts); }
 };
 
 class microsoft_mouse_device : public serial_mouse_device
 {
 public:
 	microsoft_mouse_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock);
-	virtual DECLARE_WRITE_LINE_MEMBER( input_dtr ) { m_dtr = state; check_state(); }
-	virtual DECLARE_WRITE_LINE_MEMBER( input_rts ) { m_rts = state; check_state(); m_old_rts = state; }
 
 protected:
+	virtual WRITE_LINE_MEMBER(input_rts);
+
 	virtual void set_frame() { set_data_frame(1, 7, PARITY_NONE, STOP_BITS_2); }
 	virtual void mouse_trans(int dx, int dy, int nb, int mbc);
-	virtual void device_reset() {m_old_rts = 0; serial_mouse_device::device_reset();}
-
-private:
-	void check_state();
-	int m_dtr;
-	int m_rts;
-	int m_old_rts;
 };
 
 extern const device_type MSFT_SERIAL_MOUSE;
@@ -67,17 +68,10 @@ class mouse_systems_mouse_device : public serial_mouse_device
 {
 public:
 	mouse_systems_mouse_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock);
-	virtual DECLARE_WRITE_LINE_MEMBER( input_dtr ) { m_dtr = state; check_state(); }
-	virtual DECLARE_WRITE_LINE_MEMBER( input_rts ) { m_rts = state; check_state(); }
 
 protected:
 	virtual void set_frame() { set_data_frame(1, 8, PARITY_NONE, STOP_BITS_2); }
 	virtual void mouse_trans(int dx, int dy, int nb, int mbc);
-
-private:
-	void check_state() { set_mouse_enable((m_dtr && m_rts)?true:false); }
-	int m_dtr;
-	int m_rts;
 };
 
 extern const device_type MSYSTEM_SERIAL_MOUSE;

src/emu/machine/ins8250.c

@@ -97,7 +97,12 @@ ins8250_uart_device::ins8250_uart_device(const machine_config &mconfig, device_t
 			m_out_rts_cb(*this),
 			m_out_int_cb(*this),
 			m_out_out1_cb(*this),
-			m_out_out2_cb(*this)
+			m_out_out2_cb(*this),
+			m_rxd(1),
+			m_dcd(1),
+			m_dsr(1),
+			m_ri(1),
+			m_cts(1)
 {
 }
 
@@ -212,20 +217,11 @@ WRITE8_MEMBER( ins8250_uart_device::ins8250_w )
 			{
 				m_regs.thr = data;
 				m_regs.lsr &= ~0x20;
-				if ( m_regs.mcr & 0x10 )
+				if((m_device_type >= TYPE_NS16550) && (m_regs.fcr & 1))
-				{
+					push_tx(data);
-					m_regs.lsr |= 0x61;
+				clear_int(COM_INT_PENDING_TRANSMITTER_HOLDING_REGISTER_EMPTY);
-					m_regs.rbr = data;
+				if(m_regs.lsr & 0x40)
-					trigger_int(COM_INT_PENDING_RECEIVED_DATA_AVAILABLE);
+					tra_complete();
-				}
-				else
-				{
-					if((m_device_type >= TYPE_NS16550) && (m_regs.fcr & 1))
-						push_tx(data);
-					clear_int(COM_INT_PENDING_TRANSMITTER_HOLDING_REGISTER_EMPTY);
-					if(m_regs.lsr & 0x40)
-						tra_complete();
-				}
 			}
 			break;
 		case 1:
@@ -289,25 +285,25 @@ WRITE8_MEMBER( ins8250_uart_device::ins8250_w )
 			{
 				m_regs.mcr = data & 0x1f;
 
-				if ( m_regs.mcr & 0x10 )        /* loopback test */
+				update_msr();
+
+				if (m_regs.mcr & 0x10)        /* loopback test */
 				{
-					data = ( ( m_regs.mcr & 0x0c ) << 4 ) | ( ( m_regs.mcr & 0x01 ) << 5 ) | ( ( m_regs.mcr & 0x02 ) << 3 );
+					m_out_tx_cb(1);
-					if ( ( m_regs.msr & 0x20 ) != ( data & 0x20 ) )
+					device_serial_interface::rx_w(m_txd);
-						data |= 0x02;
+					m_out_dtr_cb(1);
-					if ( ( m_regs.msr & 0x10 ) != ( data & 0x10 ) )
+					m_out_rts_cb(1);
-						data |= 0x01;
+					m_out_out1_cb(1);
-					if ( ( m_regs.msr & 0x40 ) && ! ( data & 0x40 ) )
+					m_out_out2_cb(1);
-						data |= 0x04;
-					if ( ( m_regs.msr & 0x80 ) != ( data & 0x80 ) )
-						data |= 0x08;
-					m_regs.msr = data;
 				}
 				else
 				{
-					m_out_dtr_cb((m_regs.mcr & 1) ? 1 : 0);
+					m_out_tx_cb(m_txd);
-					m_out_rts_cb((m_regs.mcr & 2) ? 1 : 0);
+					device_serial_interface::rx_w(m_rxd);
-					m_out_out1_cb((m_regs.mcr & 4) ? 1 : 0);
+					m_out_dtr_cb((m_regs.mcr & 1) ? 0 : 1);
-					m_out_out2_cb((m_regs.mcr & 8) ? 1 : 0);
+					m_out_rts_cb((m_regs.mcr & 2) ? 0 : 1);
+					m_out_out1_cb((m_regs.mcr & 4) ? 0 : 1);
+					m_out_out2_cb((m_regs.mcr & 8) ? 0 : 1);
 				}
 			}
 			break;
@@ -327,15 +323,7 @@ WRITE8_MEMBER( ins8250_uart_device::ins8250_w )
 
 			break;
 		case 6:
-			/*
+			// modem status register is read only
-			  This register can be written, but if you write a 1 bit into any of
-			  bits 3 - 0, you could cause an interrupt if the appropriate IER bit
-			  is set.
-			 */
-			m_regs.msr = data;
-
-			if ( m_regs.msr & 0x0f )
-				trigger_int(COM_INT_PENDING_MODEM_STATUS_REGISTER);
 			break;
 		case 7:
 			m_regs.scr = data;
@@ -354,7 +342,7 @@ READ8_MEMBER( ins8250_uart_device::ins8250_r )
 				data = (m_regs.dl & 0xff);
 			else
 			{
-				if((m_device_type >= TYPE_NS16550) && (m_regs.fcr & 1) && !(m_regs.mcr & 0x10))
+				if((m_device_type >= TYPE_NS16550) && (m_regs.fcr & 1))
 					m_regs.rbr = pop_rx();
 				else
 				{
@@ -482,37 +470,66 @@ void ins8250_uart_device::tra_complete()
 
 void ins8250_uart_device::tra_callback()
 {
-	m_out_tx_cb(transmit_register_get_data_bit());
+	m_txd = transmit_register_get_data_bit();
+	if (m_regs.mcr & 0x10)
+	{
+		device_serial_interface::rx_w(m_txd);
+	}
+	else
+	{
+		m_out_tx_cb(m_txd);
+	}
 }
 
-void ins8250_uart_device::update_msr(int bit, UINT8 state)
+void ins8250_uart_device::update_msr()
 {
-	UINT8 mask = (1<<bit);
+	UINT8 data;
-	if((m_regs.msr & mask) == (state<<bit))
+
-		return;
+	if (m_regs.mcr & 0x10)
-	m_regs.msr |= mask;
+		data = ((m_regs.mcr & 0x0c) << 4) | ((m_regs.mcr & 0x01) << 5) | ((m_regs.mcr & 0x02) << 3);
-	m_regs.msr = (m_regs.msr & ~(mask << 4)) | (state<<(bit+4));
+	else
-	trigger_int(COM_INT_PENDING_MODEM_STATUS_REGISTER);
+		data = (!m_dcd << 7) | (!m_ri << 6) | (!m_dsr << 5) | (!m_cts << 4);
+
+	int change = (m_regs.msr ^ data) >> 4;
+
+	if (change)
+	{
+		m_regs.msr = data | (m_regs.msr & 0xf) | change;
+
+		trigger_int(COM_INT_PENDING_MODEM_STATUS_REGISTER);
+	}
 }
 
 WRITE_LINE_MEMBER(ins8250_uart_device::dcd_w)
 {
-	update_msr(3, (state ? 1 : 0));
+	m_dcd = state;
+	update_msr();
 }
 
 WRITE_LINE_MEMBER(ins8250_uart_device::dsr_w)
 {
-	update_msr(1, (state ? 1 : 0));
+	m_dsr = state;
+	update_msr();
 }
 
 WRITE_LINE_MEMBER(ins8250_uart_device::ri_w)
 {
-	update_msr(2, (state ? 1 : 0));
+	m_ri = state;
+	update_msr();
 }
 
 WRITE_LINE_MEMBER(ins8250_uart_device::cts_w)
 {
-	update_msr(0, (state ? 1 : 0));
+	m_cts = state;
+	update_msr();
+}
+
+WRITE_LINE_MEMBER(ins8250_uart_device::rx_w)
+{
+	m_rxd = state;
+
+	if (!(m_regs.mcr & 0x10))
+		device_serial_interface::rx_w(m_rxd);
 }
 
 void ins8250_uart_device::device_start()
@@ -525,7 +542,6 @@ void ins8250_uart_device::device_start()
 	m_out_out2_cb.resolve_safe();
 	set_tra_rate(0);
 	set_rcv_rate(0);
-	memset(&m_regs, 0x00, sizeof(m_regs));
 
 	device_serial_interface::register_save_state(machine().save(), name(), tag());
 	save_item(NAME(m_regs.thr));
@@ -540,24 +556,32 @@ void ins8250_uart_device::device_start()
 	save_item(NAME(m_regs.msr));
 	save_item(NAME(m_regs.scr));
 	save_item(NAME(m_int_pending));
+	save_item(NAME(m_txd));
+	save_item(NAME(m_rxd));
+	save_item(NAME(m_dcd));
+	save_item(NAME(m_dsr));
+	save_item(NAME(m_ri));
+	save_item(NAME(m_cts));
 }
 
 void ins8250_uart_device::device_reset()
 {
-	memset(&m_regs, 0x00, sizeof(m_regs));
 	m_regs.ier = 0;
 	m_regs.iir = 1;
 	m_regs.lcr = 0;
 	m_regs.mcr = 0;
 	m_regs.lsr = (1<<5) | (1<<6);
+	update_msr();
+	m_regs.msr &= 0xf0;
 	m_int_pending = 0;
 	receive_register_reset();
 	transmit_register_reset();
-	m_out_rts_cb(0);
+	m_txd = 1;
-	m_out_dtr_cb(0);
-	m_out_out1_cb(0);
-	m_out_out2_cb(0);
 	m_out_tx_cb(1);
+	m_out_rts_cb(1);
+	m_out_dtr_cb(1);
+	m_out_out1_cb(1);
+	m_out_out2_cb(1);
 }
 
 void ins8250_uart_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)

src/emu/machine/ins8250.h

@@ -32,7 +32,7 @@ public:
 	DECLARE_WRITE_LINE_MEMBER( dsr_w );
 	DECLARE_WRITE_LINE_MEMBER( ri_w );
 	DECLARE_WRITE_LINE_MEMBER( cts_w );
-	DECLARE_WRITE_LINE_MEMBER( rx_w ) { device_serial_interface::rx_w(state); }
+	DECLARE_WRITE_LINE_MEMBER( rx_w );
 
 protected:
 	virtual void device_start();
@@ -81,7 +81,14 @@ private:
 	devcb_write_line    m_out_out2_cb;
 
 	void update_interrupt();
-	void update_msr(int bit, UINT8 state);
+	void update_msr();
+
+	int m_txd;
+	int m_rxd;
+	int m_dcd;
+	int m_dsr;
+	int m_ri;
+	int m_cts;
 };
 
 class ins8250_device : public ins8250_uart_device