diff --git a/src/emu/machine/rtc4543.c b/src/emu/machine/rtc4543.c
index 78b2b7fd9d7..6c17c12c7f5 100644
--- a/src/emu/machine/rtc4543.c
+++ b/src/emu/machine/rtc4543.c
@@ -52,6 +52,7 @@ void rtc4543_device::device_start()
 	save_item(NAME(m_clk));
 	save_item(NAME(m_wr));
 	save_item(NAME(m_data));
+	save_item(NAME(m_shiftreg));
 	save_item(NAME(m_regs));
 	save_item(NAME(m_curreg));
 }
@@ -69,7 +70,9 @@ void rtc4543_device::device_reset()
 	m_wr = 0;
 	m_clk = 0;
 	m_data = 0;
+	m_shiftreg = 0;
 	m_curreg = 0;
+	m_curbit = 0;
 }
 
 
@@ -96,16 +99,16 @@ void rtc4543_device::rtc_clock_updated(int year, int month, int day, int day_of_
 {
 	static const int weekday[7] = { 7, 1, 2, 3, 4, 5, 6 };
 
-	m_regs[0] = make_bcd(second);               // seconds (BCD, 0-59) in bits 0-6, bit 7 = battery low
-	m_regs[1] = make_bcd(minute);               // minutes (BCD, 0-59)
-	m_regs[2] = make_bcd(hour);                 // hour (BCD, 0-23)
-	m_regs[3] = make_bcd(weekday[day_of_week-1]);   // low nibble = day of the week
-	m_regs[3] |= (make_bcd(day) & 0x0f)<<4;     // high nibble = low digit of day
-	m_regs[4] = (make_bcd(day) >> 4);           // low nibble = high digit of day
-	m_regs[4] |= (make_bcd(month & 0x0f)<<4);   // high nibble = low digit of month
-	m_regs[5] = make_bcd(month & 0x0f) >> 4;    // low nibble = high digit of month
-	m_regs[5] |= (make_bcd(year % 10) << 4);    // high nibble = low digit of year
-	m_regs[6] = make_bcd(year % 100) >> 4;  // low nibble = tens digit of year (BCD, 0-9)
+	m_regs[0] = make_bcd(second);                   // seconds (BCD, 0-59) in bits 0-6, bit 7 = battery low
+	m_regs[1] = make_bcd(minute);                   // minutes (BCD, 0-59)
+	m_regs[2] = make_bcd(hour);                     // hour (BCD, 0-23)
+	m_regs[3] = make_bcd(weekday[day_of_week - 1]); // low nibble = day of the week
+	m_regs[3] |= (make_bcd(day) & 0x0f) << 4;       // high nibble = low digit of day
+	m_regs[4] = (make_bcd(day) >> 4);               // low nibble = high digit of day
+	m_regs[4] |= (make_bcd(month & 0x0f) << 4);     // high nibble = low digit of month
+	m_regs[5] = make_bcd(month & 0x0f) >> 4;        // low nibble = high digit of month
+	m_regs[5] |= (make_bcd(year % 10) << 4);        // high nibble = low digit of year
+	m_regs[6] = make_bcd(year % 100) >> 4;          // low nibble = tens digit of year (BCD, 0-9)
 }
 
 //-------------------------------------------------
@@ -116,13 +119,13 @@ WRITE_LINE_MEMBER( rtc4543_device::ce_w )
 {
 	if (VERBOSE) printf("RTC4543 '%s' CE: %u\n", tag(), state);
 
-	if (!state && m_ce)         // complete transfer
+	if (!state && m_ce) // complete transfer
 	{
 	}
-	else if (state && !m_ce)    // start new data transfer
+	else if (state && !m_ce) // start new data transfer
 	{
 		m_curreg = 0;
-		m_bit = 8;      // force immediate reload of output data
+		m_curbit = 0; // force immediate reload of output data
 	}
 
 	m_ce = state;
@@ -149,25 +152,29 @@ WRITE_LINE_MEMBER( rtc4543_device::clk_w )
 
 	if (!m_ce) return;
 
-	if (!m_clk && state) // rising edge - read data becomes valid here
+	// rising edge - read data becomes valid here
+	if (!m_clk && state)
 	{
 		if (!m_wr)
 		{
-			if (m_bit > 7)  // reload data?
+			// reload data?
+			if ((m_curbit & 7) == 0)
 			{
-				m_bit = 0;
-				m_data = m_regs[m_curreg++];
+				m_shiftreg = m_regs[m_curreg++];
+
 				if (VERBOSE)
-					logerror("RTC4543 '%s' sending byte: %02x\n", tag(), m_data);
+					logerror("RTC4543 '%s' sending byte: %02x\n", tag(), m_shiftreg);
 			}
-			else            // no reload, just continue with the current byte
+
+			// shift data bit
+			// note: output data does not change when clk at final bit
+			if (m_curbit != 55)
 			{
-				m_data >>= 1;
+				m_data = m_shiftreg & 1;
+				m_curbit++;
+				m_shiftreg >>= 1;
+				data_cb(m_data);
 			}
-
-			m_bit++;
-
-			data_cb(m_data & 0x01);
 		}
 	}
 
@@ -183,7 +190,7 @@ WRITE_LINE_MEMBER( rtc4543_device::data_w )
 {
 	if (VERBOSE) logerror("RTC4543 '%s' I/O: %u\n", tag(), state);
 
-	m_data |= (state & 1);
+	m_data = state & 1;
 }
 
 
@@ -193,5 +200,5 @@ WRITE_LINE_MEMBER( rtc4543_device::data_w )
 
 READ_LINE_MEMBER( rtc4543_device::data_r )
 {
-	return (m_data & 0x80) ? 1 : 0;
+	return m_data;
 }
diff --git a/src/emu/machine/rtc4543.h b/src/emu/machine/rtc4543.h
index dd7c11cf392..1b917566401 100644
--- a/src/emu/machine/rtc4543.h
+++ b/src/emu/machine/rtc4543.h
@@ -64,9 +64,10 @@ private:
 	int m_clk;
 	int m_wr;
 	int m_data;
+	int m_shiftreg;
 	int m_regs[7];
 	int m_curreg;
-	int m_bit;
+	int m_curbit;
 
 	// timers
 	emu_timer *m_clock_timer;