diff -upr mess-git/src/emu/bus/sms_ctrl/sports.c mess-new/src/emu/bus/sms_ctrl/sports.c
--- mess-git/src/emu/bus/sms_ctrl/sports.c	2015-09-12 22:45:26.000000000 -0300
+++ mess-new/src/emu/bus/sms_ctrl/sports.c	2015-09-13 01:33:14.000000000 -0300
@@ -6,6 +6,22 @@
 
 **********************************************************************/
 
+// The games designed for the US model of the Sports Pad controller use the
+// TH line of the controller port as output, to select which nibble, of the
+// two axis bytes, will be read at a time. The Japanese cartridge Sports Pad
+// Soccer uses a different mode, because the Sega Mark III lacks TH output, so
+// there is a different Sports Pad model released in Japan (see sportsjp.c).
+
+// It was discovered that games designed for the Paddle Controller, released
+// in Japan, switch to a mode incompatible with the original Paddle when
+// detect the system region as Export. Similar to how the US model of the
+// Sports Pad works, that mode uses the TH line as output to select which
+// nibble of the X axis will be read. So, on an Export console version, paddle
+// games are somewhat playable with the US Sport Pad model, though it needs to
+// be used inverted and the trackball needs to be moved slowly, else the
+// software for the paddle think it's moving backward.
+// See http://mametesters.org/view.php?id=5872 for discussion.
+
 #include "sports.h"
 
 
@@ -16,32 +32,33 @@
 
 const device_type SMS_SPORTS_PAD = &device_creator<sms_sports_pad_device>;
 
-
+// time interval not verified
 #define SPORTS_PAD_INTERVAL attotime::from_hz(XTAL_53_693175MHz/15/512)
 
 
-CUSTOM_INPUT_MEMBER( sms_sports_pad_device::dir_pins_r )
+void sms_sports_pad_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
 {
-	UINT8 data = 0;
-
-	switch (m_read_state)
+	switch (id)
 	{
-	case 0:
-		data = m_sports_x->read() >> 4;
-		break;
-	case 1:
-		data = m_sports_x->read();
-		break;
-	case 2:
-		data = m_sports_y->read() >> 4;
-		break;
-	case 3:
-		data = m_sports_y->read();
+	case TIMER_SPORTSPAD:
+		// values for x and y axis need to be resetted for Sports Pad games, but
+		// are not resetted for paddle games, so it was assumed the reset occurs
+		// only when this timer fires after the read state reached maximum value.
+		if (m_read_state == 3)
+		{
+			m_x_axis_reset_value = m_sports_x->read();
+			m_y_axis_reset_value = m_sports_y->read();
+		}
+		else
+		{
+			// set to maximum value, so it wraps to 0 at next increment
+			m_read_state = 3;
+		}
+
 		break;
+	default:
+		assert_always(FALSE, "Unknown id in sms_sports_pad_device::device_timer");
 	}
-
-	// The returned value is inverted due to IP_ACTIVE_LOW mapping.
-	return ~(data & 0x0f);
 }
 
 
@@ -53,18 +70,34 @@ CUSTOM_INPUT_MEMBER( sms_sports_pad_devi
 
 INPUT_CHANGED_MEMBER( sms_sports_pad_device::th_pin_w )
 {
-	attotime cur_time = machine().time();
+	m_read_state = (m_read_state + 1) & 3;
+	m_sportspad_timer->adjust(m_interval);
+	m_last_data = newval;
+}
 
-	if (cur_time - m_last_time > m_interval)
-	{
-		m_read_state = 0;
-	}
-	else
+
+CUSTOM_INPUT_MEMBER( sms_sports_pad_device::dir_pins_r )
+{
+	UINT8 data = 0;
+
+	switch (m_read_state)
 	{
-		m_read_state = (m_read_state + 1) & 3;
+	case 0:
+		data = (m_sports_x->read() - m_x_axis_reset_value) >> 4;
+		break;
+	case 1:
+		data = (m_sports_x->read() - m_x_axis_reset_value);
+		break;
+	case 2:
+		data = (m_sports_y->read() - m_y_axis_reset_value) >> 4;
+		break;
+	case 3:
+		data = (m_sports_y->read() - m_y_axis_reset_value);
+		break;
 	}
-	m_last_time = cur_time;
-	m_last_data = newval;
+
+	// The returned value is inverted due to IP_ACTIVE_LOW mapping.
+	return ~(data & 0x0f);
 }
 
 
@@ -84,10 +117,10 @@ static INPUT_PORTS_START( sms_sports_pad
 	PORT_BIT( 0x80, IP_ACTIVE_LOW, IPT_UNUSED ) // TR (Button 2)
 
 	PORT_START("SPORTS_X")    /* Sports Pad X axis */
-	PORT_BIT( 0xff, 0x00, IPT_TRACKBALL_X ) PORT_SENSITIVITY(50) PORT_KEYDELTA(40) PORT_RESET PORT_REVERSE
+	PORT_BIT( 0xff, 0x00, IPT_TRACKBALL_X ) PORT_SENSITIVITY(50) PORT_KEYDELTA(40) PORT_REVERSE
 
 	PORT_START("SPORTS_Y")    /* Sports Pad Y axis */
-	PORT_BIT( 0xff, 0x00, IPT_TRACKBALL_Y ) PORT_SENSITIVITY(50) PORT_KEYDELTA(40) PORT_RESET PORT_REVERSE
+	PORT_BIT( 0xff, 0x00, IPT_TRACKBALL_Y ) PORT_SENSITIVITY(50) PORT_KEYDELTA(40) PORT_REVERSE
 INPUT_PORTS_END
 
 
@@ -119,6 +152,8 @@ sms_sports_pad_device::sms_sports_pad_de
 	m_sports_y(*this, "SPORTS_Y"),
 	m_read_state(0),
 	m_last_data(0),
+	m_x_axis_reset_value(0x80), // value 0x80 helps when start playing paddle games.
+	m_y_axis_reset_value(0x80),
 	m_interval(SPORTS_PAD_INTERVAL)
 {
 }
@@ -130,11 +165,12 @@ sms_sports_pad_device::sms_sports_pad_de
 
 void sms_sports_pad_device::device_start()
 {
-	m_last_time = machine().time();
+	m_sportspad_timer = timer_alloc(TIMER_SPORTSPAD);
 
 	save_item(NAME(m_read_state));
 	save_item(NAME(m_last_data));
-	save_item(NAME(m_last_time));
+	save_item(NAME(m_x_axis_reset_value));
+	save_item(NAME(m_y_axis_reset_value));
 }
 
 
diff -upr mess-git/src/emu/bus/sms_ctrl/sports.h mess-new/src/emu/bus/sms_ctrl/sports.h
--- mess-git/src/emu/bus/sms_ctrl/sports.h	2015-09-12 22:45:40.000000000 -0300
+++ mess-new/src/emu/bus/sms_ctrl/sports.h	2015-09-12 23:15:54.000000000 -0300
@@ -53,8 +53,13 @@ private:
 
 	UINT8 m_read_state;
 	UINT8 m_last_data;
+	UINT8 m_x_axis_reset_value;
+	UINT8 m_y_axis_reset_value;
 	const attotime m_interval;
-	attotime m_last_time;
+	emu_timer *m_sportspad_timer;
+	static const device_timer_id TIMER_SPORTSPAD = 0;
+
+	void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr);
 };