diff --git a/src/devices/cpu/h8/h8_port.cpp b/src/devices/cpu/h8/h8_port.cpp
index 521cc29dedd..87253cd3eb0 100644
--- a/src/devices/cpu/h8/h8_port.cpp
+++ b/src/devices/cpu/h8/h8_port.cpp
@@ -85,7 +85,7 @@ u8 h8_port_device::odr_r()
 
 void h8_port_device::update_output()
 {
-	u8 data = m_dr & m_ddr & ~m_mask;
+	u8 data = (m_dr | ~m_ddr) & ~m_mask;
 	u8 ddr = m_ddr & ~m_mask; // 0-bits = hi-z
 	u16 res = ddr << 8 | data;
 
diff --git a/src/mame/namco/namcos12.cpp b/src/mame/namco/namcos12.cpp
index 52659347f77..290ea9ce7c1 100644
--- a/src/mame/namco/namcos12.cpp
+++ b/src/mame/namco/namcos12.cpp
@@ -1178,9 +1178,9 @@ protected:
 	uint8_t s12_mcu_portB_r();
 	void s12_mcu_portB_w(uint8_t data);
 	uint8_t s12_mcu_p6_r();
-	uint16_t iob_p4_r();
-	uint16_t iob_p6_r();
-	void iob_p4_w(uint16_t data);
+	uint8_t iob_p4_r();
+	uint8_t iob_p6_r();
+	void iob_p4_w(uint8_t data);
 
 	required_device<psxcpu_device> m_maincpu;
 	required_device<ram_device> m_ram;
@@ -1212,9 +1212,7 @@ private:
 	uint32_t m_ttt_val[2];
 	uint8_t m_sub_porta;
 	uint8_t m_sub_portb;
-
 	uint8_t m_jvssense;
-	uint8_t m_tssio_port_4;
 
 	void sharedram_w(offs_t offset, uint16_t data, uint16_t mem_mask = ~0);
 	uint16_t sharedram_r(offs_t offset, uint16_t mem_mask = ~0);
@@ -1627,8 +1625,6 @@ void namcos12_state::machine_reset()
 	bankoffset_w(0,0,0xffff);
 
 	m_jvssense = 1;
-	m_tssio_port_4 = 0;
-
 	m_has_tektagt_dma = 0;
 }
 
@@ -1877,20 +1873,18 @@ void namcos12_state::jvsmap(address_map &map)
 	map(0xc000, 0xfb7f).ram();
 }
 
-uint16_t namcos12_state::iob_p4_r()
+uint8_t namcos12_state::iob_p4_r()
 {
-	return m_tssio_port_4;
+	return 0;
 }
 
-void namcos12_state::iob_p4_w(uint16_t data)
+void namcos12_state::iob_p4_w(uint8_t data)
 {
-	m_tssio_port_4 = data;
-
 	// bit 2 = SENSE line back to main (0 = asserted, 1 = dropped)
 	m_jvssense = (data & 0x04) ? 0 : 1;
 }
 
-uint16_t namcos12_state::iob_p6_r()
+uint8_t namcos12_state::iob_p6_r()
 {
 	// d4 is service button
 	uint8_t sb = (m_service_io->read() & 1) << 4;
diff --git a/src/mame/namco/namcos23.cpp b/src/mame/namco/namcos23.cpp
index 07884d40f1e..78cb76cf0ed 100644
--- a/src/mame/namco/namcos23.cpp
+++ b/src/mame/namco/namcos23.cpp
@@ -1818,7 +1818,6 @@ private:
 	uint8_t m_sub_port8;
 	uint8_t m_sub_porta;
 	uint8_t m_sub_portb;
-	uint8_t m_tssio_port_4;
 	output_finder<8> m_lamps;
 };
 
@@ -3331,13 +3330,11 @@ void namcos23_state::s23h8rwmap(address_map &map)
 
 uint8_t namcos23_state::iob_p4_r()
 {
-	return m_tssio_port_4;
+	return 0;
 }
 
 void namcos23_state::iob_p4_w(uint8_t data)
 {
-	m_tssio_port_4 = data;
-
 	// bit 2 = SENSE line back to main (0 = asserted, 1 = dropped)
 	m_jvssense = (data & 0x04) ? 0 : 1;
 }
@@ -3759,7 +3756,6 @@ void namcos23_state::init_s23()
 	m_sub_port8 = 0x02;
 	m_sub_porta = 0;
 	m_sub_portb = 0x50;
-	m_tssio_port_4 = 0;
 	m_subcpu_running = false;
 	m_render.count[0] = m_render.count[1] = 0;
 	m_render.cur = 0;
diff --git a/src/mame/saitek/gk2000.cpp b/src/mame/saitek/gk2000.cpp
index 1c0f4d16dc0..be6c61368d7 100644
--- a/src/mame/saitek/gk2000.cpp
+++ b/src/mame/saitek/gk2000.cpp
@@ -89,7 +89,7 @@ private:
 
 	void p2_w(u8 data);
 	u8 p4_r();
-	void p5_w(offs_t offset, u8 data, u8 mem_mask);
+	void p5_w(u8 data);
 };
 
 void gk2000_state::machine_start()
@@ -198,10 +198,8 @@ u8 gk2000_state::p4_r()
 	return ~data;
 }
 
-void gk2000_state::p5_w(offs_t offset, u8 data, u8 mem_mask)
+void gk2000_state::p5_w(u8 data)
 {
-	data |= ~mem_mask;
-
 	// P50: speaker out
 	m_dac->write(data & 1);
 
diff --git a/src/mame/yamaha/ymmu100.cpp b/src/mame/yamaha/ymmu100.cpp
index 181e0f54e48..a6e2dae03c9 100644
--- a/src/mame/yamaha/ymmu100.cpp
+++ b/src/mame/yamaha/ymmu100.cpp
@@ -337,7 +337,7 @@ u8 mu100_state::p1_r()
 void mu100_state::p2_w(u8 data)
 {
 	// LCD enable edge
-	if(!(m_cur_p2 & P2_LCD_ENABLE) && (data & P2_LCD_ENABLE)) {
+	if((m_cur_p2 & P2_LCD_ENABLE) && !(data & P2_LCD_ENABLE)) {
 		if(!(m_cur_p2 & P2_LCD_RW)) {
 			if(m_cur_p2 & P2_LCD_RS)
 				m_lcd->data_write(m_cur_p1);
diff --git a/src/mame/yamaha/ymmu128.cpp b/src/mame/yamaha/ymmu128.cpp
index 8743612aadc..94c402028ee 100644
--- a/src/mame/yamaha/ymmu128.cpp
+++ b/src/mame/yamaha/ymmu128.cpp
@@ -60,17 +60,17 @@ private:
 
 	virtual void machine_start() override;
 	virtual void machine_reset() override;
-	
+
 	u16 pe_r();
 	void pe_w(u16 data);
 };
-	
+
 void mu128_state::machine_start()
 {
 	save_item(NAME(m_pe));
 	m_pe = 0;
 }
-	
+
 void mu128_state::machine_reset()
 {
 }
@@ -107,16 +107,16 @@ u16 mu128_state::pe_r()
 
 void mu128_state::pe_w(u16 data)
 {
-	u16 prev = m_pe;
-	m_pe = data;
-	if(BIT(m_pe, 4) && !BIT(prev, 4)) {
-		if(!BIT(m_pe, 0)) {
-			if(BIT(m_pe, 2))
-				m_lcd->data_write(m_pe >> 8);
+	if(BIT(m_pe, 4) && !BIT(data, 4)) {
+		if(!BIT(data, 0)) {
+			if(BIT(data, 2))
+				m_lcd->data_write(data >> 8);
 			else
-				m_lcd->control_write(m_pe >> 8);
+				m_lcd->control_write(data >> 8);
 		}
-	}	
+	}
+
+	m_pe = data;
 }
 
 void mu128_state::map(address_map &map)
diff --git a/src/mame/yamaha/ymmu15.cpp b/src/mame/yamaha/ymmu15.cpp
index 80285e1ec93..88506fe47d2 100644
--- a/src/mame/yamaha/ymmu15.cpp
+++ b/src/mame/yamaha/ymmu15.cpp
@@ -109,7 +109,7 @@ u16 mu15_state::adc_battery_r()
 void mu15_state::p6_w(u8 data)
 {
 	data ^= P6_LCD_ENABLE;
-	if(!(cur_p6 & P6_LCD_ENABLE) && (data & P6_LCD_ENABLE)) {
+	if((cur_p6 & P6_LCD_ENABLE) && !(data & P6_LCD_ENABLE)) {
 		if(!(cur_p6 & P6_LCD_RW)) {
 			if(cur_p6 & P6_LCD_RS)
 				m_lcd->data_write(cur_pa);
diff --git a/src/mame/yamaha/ymmu50.cpp b/src/mame/yamaha/ymmu50.cpp
index bf55e2db565..16586faaeef 100644
--- a/src/mame/yamaha/ymmu50.cpp
+++ b/src/mame/yamaha/ymmu50.cpp
@@ -160,7 +160,7 @@ u16 mu50_state::adc_battery_r()
 void mu50_state::p6_w(u8 data)
 {
 	data ^= P6_LCD_ENABLE;
-	if(!(cur_p6 & P6_LCD_ENABLE) && (data & P6_LCD_ENABLE)) {
+	if((cur_p6 & P6_LCD_ENABLE) && !(data & P6_LCD_ENABLE)) {
 		if(!(cur_p6 & P6_LCD_RW)) {
 			if(cur_p6 & P6_LCD_RS)
 				m_lcd->data_write(cur_pa);
diff --git a/src/mame/yamaha/ymmu80.cpp b/src/mame/yamaha/ymmu80.cpp
index 7d9d88e22b5..065fcc63cb8 100644
--- a/src/mame/yamaha/ymmu80.cpp
+++ b/src/mame/yamaha/ymmu80.cpp
@@ -178,18 +178,6 @@ public:
 	void mu80(machine_config &config);
 
 private:
-	enum {
-		P2_LCD_RS     = 0x01,
-		P2_LCD_RW     = 0x02,
-		P2_LCD_ENABLE = 0x04
-	};
-
-	enum {
-		P6_LCD_RS     = 0x04,
-		P6_LCD_RW     = 0x02,
-		P6_LCD_ENABLE = 0x01
-	};
-
 	enum {
 		PA_LCD_RS     = 0x02,
 		PA_LCD_ENABLE = 0x20,
@@ -310,7 +298,7 @@ u8 mu80_state::p6_r()
 void mu80_state::pa_w(u8 data)
 {
 	data ^= PA_LCD_ENABLE;
-	if(!(cur_pa & PA_LCD_ENABLE) && (data & PA_LCD_ENABLE)) {
+	if((cur_pa & PA_LCD_ENABLE) && !(data & PA_LCD_ENABLE)) {
 		if(!(cur_pa & PA_LCD_RW)) {
 			if(cur_pa & PA_LCD_RS)
 				m_lcd->data_write(cur_pb);
diff --git a/src/mame/yamaha/ymmu90.cpp b/src/mame/yamaha/ymmu90.cpp
index 3d625d3aed7..d29708bd899 100644
--- a/src/mame/yamaha/ymmu90.cpp
+++ b/src/mame/yamaha/ymmu90.cpp
@@ -175,7 +175,7 @@ void mu90_state::pa_w(u8 data)
 		logerror("ad2 input level %s\n", cur_pb & 0x40 ? "line" : "mic");
 	}
 
-	if(!(cur_pa & 0x20) && (data & 0x20)) {
+	if((cur_pa & 0x20) && !(data & 0x20)) {
 		if(!(cur_pa & 0x40)) {
 			if(cur_pa & 0x02)
 				m_lcd->data_write(cur_pb);
diff --git a/src/mame/yamaha/ymvl70.cpp b/src/mame/yamaha/ymvl70.cpp
index eae1579d285..3938f6714bb 100644
--- a/src/mame/yamaha/ymvl70.cpp
+++ b/src/mame/yamaha/ymvl70.cpp
@@ -123,12 +123,12 @@ u16 vl70_state::adc_breath_r()
 
 void vl70_state::p6_w(u8 data)
 {
-	if(!(cur_p6 & P6_LCD_ENABLE) && (data & P6_LCD_ENABLE)) {
-	if(!(cur_p6 & P6_LCD_RW)) {
-		if(cur_p6 & P6_LCD_RS)
-			m_lcd->data_write(cur_pa);
-		else
-			m_lcd->control_write(cur_pa);
+	if((cur_p6 & P6_LCD_ENABLE) && !(data & P6_LCD_ENABLE)) {
+		if(!(cur_p6 & P6_LCD_RW)) {
+			if(cur_p6 & P6_LCD_RS)
+				m_lcd->data_write(cur_pa);
+			else
+				m_lcd->control_write(cur_pa);
 		}
 	}