h8: fix standby time travel problem

src/devices/cpu/h8/gt913.cpp

@@ -253,6 +253,12 @@ void gt913_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void gt913_device::notify_standby(int state)
+{
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+}
+
 void gt913_device::execute_set_input(int inputnum, int state)
 {
 	m_intc->set_input(inputnum, state);

src/devices/cpu/h8/gt913.h

@@ -56,6 +56,7 @@ protected:
 	virtual void update_irq_filter() override;
 	virtual void interrupt_taken() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void irq_setup() override;
 	virtual void execute_set_input(int inputnum, int state) override;
 

src/devices/cpu/h8/h8.cpp

@@ -13,10 +13,6 @@
       mode) and the power button triggers an IRQ to wake up instead of RES.
       Obviously, MAME always starts at reset-phase at power-on, so it's more
       like a 'known issue' instead of a TODO since it can't really be fixed.
-    - SSBY is supposed to halt the clock. But in MAME, peripherals remember
-      the last update time and will try to catch up (a lot) after the CPU
-      wakes up. For example, if h8_watchdog was enabled, it will immediately
-      trigger a reset after wake up.
     - add STBY pin (hardware standby mode, can only wake up with reset)
 
 ***************************************************************************/
@@ -43,7 +39,7 @@ h8_device::h8_device(const machine_config &mconfig, device_type type, const char
 	m_PPC(0), m_NPC(0), m_PC(0), m_PIR(0), m_EXR(0), m_CCR(0), m_MAC(0), m_MACF(0),
 	m_TMP1(0), m_TMP2(0), m_TMPR(0), m_inst_state(0), m_inst_substate(0), m_icount(0), m_bcount(0),
 	m_irq_vector(0), m_taken_irq_vector(0), m_irq_level(0), m_taken_irq_level(0), m_irq_required(false), m_irq_nmi(false),
-	m_standby_pending(false), m_nvram_defval(0), m_nvram_battery(true)
+	m_standby_pending(false), m_standby_time(0), m_nvram_defval(0), m_nvram_battery(true)
 {
 	m_supports_advanced = false;
 	m_mode_advanced = false;
@@ -169,6 +165,7 @@ void h8_device::device_start()
 	save_item(NAME(m_irq_nmi));
 	save_item(NAME(m_current_dma));
 	save_item(NAME(m_standby_pending));
+	save_item(NAME(m_standby_time));
 	save_item(NAME(m_nvram_battery));
 
 	set_icountptr(m_icount);
@@ -583,6 +580,7 @@ void h8_device::set_irq(int irq_vector, int irq_level, bool irq_nmi)
 
 	// wake up from software standby with an external interrupt
 	if(standby() && m_irq_vector) {
+		notify_standby(0);
 		resume(SUSPEND_REASON_CLOCK);
 		m_standby_cb(0);
 		take_interrupt();

src/devices/cpu/h8/h8.h

@@ -49,6 +49,7 @@ public:
 	void nvram_set_default_value(u16 val) { m_nvram_defval = val; } // default is 0
 	auto standby_cb() { return m_standby_cb.bind(); } // notifier (not an output pin)
 	int standby() { return suspended(SUSPEND_REASON_CLOCK) ? 1 : 0; }
+	u64 standby_time() { return m_standby_time; }
 
 	void internal_update();
 	void set_irq(int irq_vector, int irq_level, bool irq_nmi);
@@ -155,20 +156,20 @@ protected:
 	h8_dma_state *m_dma_channel[8];
 	int m_current_dma;
 	h8_dtc_state *m_current_dtc;
-	u64  m_cycles_base;
+	u64 m_cycles_base;
 
-	u32  m_PPC;             // previous program counter
-	u32  m_NPC;             // next start-of-instruction program counter
-	u32  m_PC;              // program counter
-	u16  m_PIR;             // Prefetched word
-	u16  m_IR[5];           // Fetched instruction
-	u16  m_R[16];           // Rn (0-7), En (8-15, h8-300h+)
-	u8   m_EXR;             // Interrupt/trace register (h8s/2000+)
-	u8   m_CCR;             // Condition-code register
-	s64   m_MAC;            // Multiply accumulator (h8s/2600+)
-	u8   m_MACF;            // MAC flags (h8s/2600+)
-	u32  m_TMP1, m_TMP2;
-	u32  m_TMPR;            // For debugger ER register import
+	u32 m_PPC;              // previous program counter
+	u32 m_NPC;              // next start-of-instruction program counter
+	u32 m_PC;               // program counter
+	u16 m_PIR;              // Prefetched word
+	u16 m_IR[5];            // Fetched instruction
+	u16 m_R[16];            // Rn (0-7), En (8-15, h8-300h+)
+	u8 m_EXR;               // Interrupt/trace register (h8s/2000+)
+	u8 m_CCR;               // Condition-code register
+	s64 m_MAC;              // Multiply accumulator (h8s/2600+)
+	u8 m_MACF;              // MAC flags (h8s/2600+)
+	u32 m_TMP1, m_TMP2;
+	u32 m_TMPR;             // For debugger ER register import
 
 	bool m_has_exr, m_has_mac, m_has_trace, m_supports_advanced, m_mode_advanced, m_mode_a20, m_mac_saturating;
 	bool m_has_hc; // GT913's CCR bit 5 is I, not H
@@ -179,6 +180,7 @@ protected:
 	int m_irq_level, m_taken_irq_level;
 	bool m_irq_required, m_irq_nmi;
 	bool m_standby_pending;
+	u64 m_standby_time;
 	u16 m_nvram_defval;
 	bool m_nvram_battery;
 
@@ -189,6 +191,7 @@ protected:
 	virtual void update_irq_filter() = 0;
 	virtual void interrupt_taken() = 0;
 	virtual void internal_update(u64 current_time) = 0;
+	virtual void notify_standby(int state) = 0;
 	void recompute_bcount(u64 event_time);
 	virtual int trace_setup();
 	virtual int trapa_setup();

src/devices/cpu/h8/h8.lst

@@ -742,6 +742,8 @@ macro jsr32 %opc %spreg
 0180         ffff         0 sleep    -        -
 	prefetch_start
 	if(m_standby_pending) {
+		m_standby_time = total_cycles();
+		notify_standby(1);
 		suspend(SUSPEND_REASON_CLOCK, true);
 		m_standby_cb(1);
 	} else {

src/devices/cpu/h8/h83002.cpp

@@ -233,6 +233,19 @@ void h83002_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h83002_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_timer16_3->notify_standby(state);
+	m_timer16_4->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83002_device::device_start()
 {
 	h8h_device::device_start();

src/devices/cpu/h8/h83002.h

@@ -86,6 +86,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h83003.cpp

@@ -260,6 +260,19 @@ void h83003_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h83003_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_timer16_3->notify_standby(state);
+	m_timer16_4->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83003_device::device_start()
 {
 	h8h_device::device_start();

src/devices/cpu/h8/h83003.h

@@ -96,6 +96,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h83006.cpp

@@ -227,6 +227,22 @@ void h83006_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h83006_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_sci[2]->notify_standby(state);
+	m_timer8_0->notify_standby(state);
+	m_timer8_1->notify_standby(state);
+	m_timer8_2->notify_standby(state);
+	m_timer8_3->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83006_device::device_start()
 {
 	h8h_device::device_start();

src/devices/cpu/h8/h83006.h

@@ -79,6 +79,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h83008.cpp

@@ -204,6 +204,21 @@ void h83008_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h83008_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_timer8_0->notify_standby(state);
+	m_timer8_1->notify_standby(state);
+	m_timer8_2->notify_standby(state);
+	m_timer8_3->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83008_device::device_start()
 {
 	h8h_device::device_start();

src/devices/cpu/h8/h83008.h

@@ -76,6 +76,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h83032.cpp

@@ -228,6 +228,18 @@ void h83032_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h83032_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_timer16_3->notify_standby(state);
+	m_timer16_4->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83032_device::device_start()
 {
 	h8h_device::device_start();

src/devices/cpu/h8/h83032.h

@@ -86,6 +86,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h83042.cpp

@@ -263,6 +263,19 @@ void h83042_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h83042_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_timer16_3->notify_standby(state);
+	m_timer16_4->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83042_device::device_start()
 {
 	h8h_device::device_start();

src/devices/cpu/h8/h83042.h

@@ -94,6 +94,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h83048.cpp

@@ -268,6 +268,19 @@ void h83048_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h83048_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_timer16_3->notify_standby(state);
+	m_timer16_4->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83048_device::device_start()
 {
 	h8h_device::device_start();

src/devices/cpu/h8/h83048.h

@@ -98,6 +98,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h83217.cpp

@@ -186,16 +186,27 @@ void h83217_device::internal_update(u64 current_time)
 
 	add_event(event_time, m_sci[0]->internal_update(current_time));
 	add_event(event_time, m_sci[1]->internal_update(current_time));
-
-	for (auto & timer8 : m_timer8)
-		add_event(event_time, timer8->internal_update(current_time));
-
+	add_event(event_time, m_timer8[0]->internal_update(current_time));
+	add_event(event_time, m_timer8[1]->internal_update(current_time));
+	add_event(event_time, m_timer8[2]->internal_update(current_time));
 	add_event(event_time, m_timer16_0->internal_update(current_time));
 	add_event(event_time, m_watchdog->internal_update(current_time));
 
 	recompute_bcount(event_time);
 }
 
+void h83217_device::notify_standby(int state)
+{
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+
+	for (auto & timer8 : m_timer8)
+		timer8->notify_standby(state);
+
+	m_timer16_0->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83217_device::device_start()
 {
 	h8_device::device_start();

src/devices/cpu/h8/h83217.h

@@ -81,6 +81,7 @@ protected:
 	virtual void interrupt_taken() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h8325.cpp

@@ -179,6 +179,15 @@ void h8325_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h8325_device::notify_standby(int state)
+{
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_timer8[0]->notify_standby(state);
+	m_timer8[1]->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+}
+
 void h8325_device::device_start()
 {
 	h8_device::device_start();

src/devices/cpu/h8/h8325.h

@@ -81,6 +81,7 @@ protected:
 	virtual void interrupt_taken() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h83337.cpp

@@ -193,6 +193,17 @@ void h83337_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h83337_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_timer8_0->notify_standby(state);
+	m_timer8_1->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h83337_device::device_start()
 {
 	h8_device::device_start();

src/devices/cpu/h8/h83337.h

@@ -92,6 +92,7 @@ protected:
 	virtual void interrupt_taken() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h8_adc.cpp

@@ -149,6 +149,12 @@ u64 h8_adc_device::internal_update(u64 current_time)
 	return m_next_event;
 }
 
+void h8_adc_device::notify_standby(int state)
+{
+	if(!state && m_next_event)
+		m_next_event += m_cpu->total_cycles() - m_cpu->standby_time();
+}
+
 void h8_adc_device::conversion_wait(bool first, bool poweron, u64 current_time)
 {
 	if(current_time)

src/devices/cpu/h8/h8_adc.h

@@ -35,6 +35,7 @@ public:
 
 	void set_suspend(bool suspend);
 	u64 internal_update(u64 current_time);
+	void notify_standby(int state);
 
 protected:
 	h8_adc_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock);

src/devices/cpu/h8/h8_sci.cpp

@@ -136,7 +136,7 @@ void h8_sci_device::scr_w(u8 data)
 			  data & SCR_TEIE ? " tei" : "",
 			  data & SCR_CKE,
 			  m_cpu->pc());
-	
+
 	u8 delta = m_scr ^ data;
 	m_scr = data;
 	clock_update();
@@ -208,7 +208,8 @@ u8 h8_sci_device::ssr_r()
 u8 h8_sci_device::rdr_r()
 {
 	LOGMASKED(LOG_RREGS, "rdr_r %02x (%06x)\n", m_rdr, m_cpu->pc());
-	if(m_cpu->access_is_dma())
+
+	if(!machine().side_effects_disabled() && m_cpu->access_is_dma())
 		m_ssr &= ~SSR_RDRF;
 	return m_rdr;
 }
@@ -292,7 +293,6 @@ void h8_sci_device::device_start()
 		m_internal_to_external_ratio = 1/m_external_to_internal_ratio;
 	}
 
-
 	save_item(NAME(m_rdr));
 	save_item(NAME(m_tdr));
 	save_item(NAME(m_smr));
@@ -315,7 +315,6 @@ void h8_sci_device::device_start()
 	save_item(NAME(m_ext_clock_value));
 	save_item(NAME(m_tx_clock_counter));
 	save_item(NAME(m_rx_clock_counter));
-	save_item(NAME(m_cur_sync_time));
 }
 
 void h8_sci_device::device_reset()
@@ -350,12 +349,17 @@ TIMER_CALLBACK_MEMBER(h8_sci_device::sync_tick)
 
 void h8_sci_device::do_rx_w(int state)
 {
+	if(m_cpu->standby()) {
+		m_rx_value = state;
+		return;
+	}
+
 	if(state != m_rx_value && (m_clock_state & CLK_RX))
 		if(m_rx_clock_counter == 1 || m_rx_clock_counter == 15)
 			m_rx_clock_counter = 0;
 
 	m_rx_value = state;
-	if(!m_rx_value && !(m_clock_state & CLK_RX) && m_rx_state != ST_IDLE && !m_cpu->standby())
+	if(!m_rx_value && !(m_clock_state & CLK_RX) && m_rx_state != ST_IDLE)
 		clock_start(CLK_RX);
 }
 
@@ -377,7 +381,7 @@ void h8_sci_device::do_clk_w(int state)
 		if(m_clock_state & CLK_TX)
 			tx_sync_tick();
 		if(m_clock_state & CLK_RX)
-			rx_sync_tick();		
+			rx_sync_tick();
 	}
 }
 
@@ -395,7 +399,7 @@ u64 h8_sci_device::internal_update(u64 current_time)
 		if(m_clock_state & CLK_TX)
 			tx_sync_tick();
 		if(m_clock_state & CLK_RX)
-			rx_sync_tick();		
+			rx_sync_tick();
 	}
 
 	if(m_clock_state) {
@@ -420,6 +424,12 @@ u64 h8_sci_device::internal_update(u64 current_time)
 	return m_clock_event;
 }
 
+void h8_sci_device::notify_standby(int state)
+{
+	if(!state && m_clock_event)
+		m_clock_event += m_cpu->total_cycles() - m_cpu->standby_time();
+}
+
 void h8_sci_device::clock_start(int mode)
 {
 	// Happens when back-to-back
@@ -509,7 +519,7 @@ void h8_sci_device::tx_async_tick()
 			m_cpu->do_sci_clk(m_id, 0);
 
 	} else if(m_tx_clock_counter == 8 && m_clock_mode == INTERNAL_ASYNC_OUT)
-		m_cpu->do_sci_clk(m_id, 1);		
+		m_cpu->do_sci_clk(m_id, 1);
 }
 
 void h8_sci_device::tx_async_step()
@@ -597,7 +607,7 @@ void h8_sci_device::tx_sync_tick()
 			m_cpu->do_sci_clk(m_id, 0);
 
 	} else if(m_tx_clock_counter == 1 && m_clock_mode == INTERNAL_SYNC_OUT)
-		m_cpu->do_sci_clk(m_id, 1);		
+		m_cpu->do_sci_clk(m_id, 1);
 }
 
 void h8_sci_device::tx_sync_step()
@@ -610,7 +620,7 @@ void h8_sci_device::tx_sync_step()
 		m_ssr |= SSR_TEND;
 		if(m_scr & SCR_TEIE)
 			m_intc->internal_interrupt(m_tei_int);
-		
+
 		// if there's more to send, start the transmitter
 		if((m_scr & SCR_TE) && !(m_ssr & SSR_TDRE))
 			tx_start();

src/devices/cpu/h8/h8_sci.h

@@ -52,6 +52,7 @@ public:
 	void do_clk_w(int state);
 
 	u64 internal_update(u64 current_time);
+	void notify_standby(int state);
 
 protected:
 	enum {
@@ -106,7 +107,7 @@ protected:
 
 	required_device<h8_device> m_cpu;
 	required_device<h8_intc_device> m_intc;
-	attotime m_external_clock_period, m_cur_sync_time;
+	attotime m_external_clock_period;
 	double m_external_to_internal_ratio, m_internal_to_external_ratio;
 	emu_timer *m_sync_timer;
 

src/devices/cpu/h8/h8_timer16.cpp

@@ -123,7 +123,8 @@ void h8_timer16_channel_device::tier_w(u8 data)
 
 u8 h8_timer16_channel_device::tsr_r()
 {
-	update_counter();
+	if(!machine().side_effects_disabled())
+		update_counter();
 	return isr_to_sr();
 }
 
@@ -137,7 +138,8 @@ void h8_timer16_channel_device::tsr_w(u8 data)
 
 u16 h8_timer16_channel_device::tcnt_r()
 {
-	update_counter();
+	if(!machine().side_effects_disabled())
+		update_counter();
 	return m_tcnt;
 }
 
@@ -224,6 +226,15 @@ u64 h8_timer16_channel_device::internal_update(u64 current_time)
 	return m_event_time;
 }
 
+void h8_timer16_channel_device::notify_standby(int state)
+{
+	if(!state && m_event_time) {
+		u64 delta = m_cpu->total_cycles() - m_cpu->standby_time();
+		m_event_time += delta;
+		m_last_clock_update += delta;
+	}
+}
+
 void h8_timer16_channel_device::update_counter(u64 cur_time)
 {
 	if(m_clock_type != DIV_1)

src/devices/cpu/h8/h8_timer16.h

@@ -91,6 +91,7 @@ public:
 	void tbr_w(offs_t offset, u16 data, u16 mem_mask = ~0);
 
 	u64 internal_update(u64 current_time);
+	void notify_standby(int state);
 	void set_ier(u8 value);
 	void set_enable(bool enable);
 	void tisr_w(int offset, u8 data);

src/devices/cpu/h8/h8_timer8.cpp

@@ -169,8 +169,10 @@ void h8_timer8_channel_device::tcor_w(offs_t offset, u8 data)
 
 u8 h8_timer8_channel_device::tcnt_r()
 {
-	update_counter();
-	recalc_event();
+	if(!machine().side_effects_disabled()) {
+		update_counter();
+		recalc_event();
+	}
 	return m_tcnt;
 }
 
@@ -212,6 +214,15 @@ u64 h8_timer8_channel_device::internal_update(u64 current_time)
 	return m_event_time;
 }
 
+void h8_timer8_channel_device::notify_standby(int state)
+{
+	if(!state && m_event_time) {
+		u64 delta = m_cpu->total_cycles() - m_cpu->standby_time();
+		m_event_time += delta;
+		m_last_clock_update += delta;
+	}
+}
+
 void h8_timer8_channel_device::update_counter(u64 cur_time, u64 delta)
 {
 	if(m_clock_type == DIV) {

src/devices/cpu/h8/h8_timer8.h

@@ -56,6 +56,7 @@ public:
 	void tcnt_w(u8 data);
 
 	u64 internal_update(u64 current_time);
+	void notify_standby(int state);
 	void set_extra_clock_bit(bool bit);
 
 	void chained_timer_overflow();

src/devices/cpu/h8/h8_watchdog.cpp

@@ -28,6 +28,14 @@ u64 h8_watchdog_device::internal_update(u64 current_time)
 		return 0;
 }
 
+void h8_watchdog_device::notify_standby(int state)
+{
+	if(state)
+		tcnt_update();
+	else
+		m_tcnt_cycle_base = m_cpu->total_cycles();
+}
+
 void h8_watchdog_device::tcnt_update(u64 cur_time)
 {
 	if(m_tcsr & TCSR_TME) {

src/devices/cpu/h8/h8_watchdog.h

@@ -31,6 +31,7 @@ public:
 	}
 
 	u64 internal_update(u64 current_time);
+	void notify_standby(int state);
 
 	u16 wd_r();
 	void wd_w(offs_t offset, u16 data, u16 mem_mask = ~0);

src/devices/cpu/h8/h8s2245.cpp

@@ -299,6 +299,20 @@ void h8s2245_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h8s2245_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_sci[2]->notify_standby(state);
+	m_timer8_0->notify_standby(state);
+	m_timer8_1->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h8s2245_device::device_start()
 {
 	h8s2000_device::device_start();

src/devices/cpu/h8/h8s2245.h

@@ -102,6 +102,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h8s2319.cpp

@@ -385,6 +385,20 @@ void h8s2319_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h8s2319_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_timer8[0]->notify_standby(state);
+	m_timer8[1]->notify_standby(state);
+
+	for (auto & timer16c : m_timer16c)
+		timer16c->notify_standby(state);
+
+	m_watchdog->notify_standby(state);
+}
+
 void h8s2319_device::device_start()
 {
 	h8s2000_device::device_start();

src/devices/cpu/h8/h8s2319.h

@@ -96,6 +96,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h8s2329.cpp

@@ -135,6 +135,12 @@ void h8s2320_device::map_2320(address_map &map)
 	map(0xffff06, 0xffff07).rw(m_dma, FUNC(h8s_dma_device::dmabcr_r), FUNC(h8s_dma_device::dmabcr_w));
 }
 
+void h8s2321_device::notify_standby(int state)
+{
+	h8s2319_device::notify_standby(state);
+	m_sci[2]->notify_standby(state);
+}
+
 void h8s2321_device::device_add_mconfig(machine_config &config)
 {
 	h8s2319_device::device_add_mconfig(config);

src/devices/cpu/h8/h8s2329.h

@@ -46,6 +46,7 @@ protected:
 	required_device<h8_port_device> m_port5;
 	required_device<h8_port_device> m_port6;
 
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map_2321(address_map &map);
 };

src/devices/cpu/h8/h8s2357.cpp

@@ -394,6 +394,23 @@ void h8s2357_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h8s2357_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_sci[2]->notify_standby(state);
+	m_timer8_0->notify_standby(state);
+	m_timer8_1->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_timer16_3->notify_standby(state);
+	m_timer16_4->notify_standby(state);
+	m_timer16_5->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h8s2357_device::device_start()
 {
 	h8s2000_device::device_start();

src/devices/cpu/h8/h8s2357.h

@@ -110,6 +110,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/h8s2655.cpp

@@ -406,6 +406,23 @@ void h8s2655_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void h8s2655_device::notify_standby(int state)
+{
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_sci[2]->notify_standby(state);
+	m_timer8_0->notify_standby(state);
+	m_timer8_1->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_timer16_3->notify_standby(state);
+	m_timer16_4->notify_standby(state);
+	m_timer16_5->notify_standby(state);
+	m_watchdog->notify_standby(state);
+}
+
 void h8s2655_device::device_start()
 {
 	h8s2600_device::device_start();

src/devices/cpu/h8/h8s2655.h

@@ -101,6 +101,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	void map(address_map &map);
 

src/devices/cpu/h8/swx00.cpp

@@ -412,6 +412,25 @@ void swx00_device::internal_update(u64 current_time)
 	recompute_bcount(event_time);
 }
 
+void swx00_device::notify_standby(int state)
+{
+#if 0
+	m_adc->notify_standby(state);
+	m_sci[0]->notify_standby(state);
+	m_sci[1]->notify_standby(state);
+	m_sci[2]->notify_standby(state);
+	m_timer8_0->notify_standby(state);
+	m_timer8_1->notify_standby(state);
+	m_timer16_0->notify_standby(state);
+	m_timer16_1->notify_standby(state);
+	m_timer16_2->notify_standby(state);
+	m_timer16_3->notify_standby(state);
+	m_timer16_4->notify_standby(state);
+	m_timer16_5->notify_standby(state);
+	m_watchdog->notify_standby(state);
+#endif
+}
+
 void swx00_device::device_start()
 {
 	h8s2000_device::device_start();

src/devices/cpu/h8/swx00.h

@@ -125,6 +125,7 @@ protected:
 	virtual int trapa_setup() override;
 	virtual void irq_setup() override;
 	virtual void internal_update(u64 current_time) override;
+	virtual void notify_standby(int state) override;
 	virtual void device_add_mconfig(machine_config &config) override;
 	virtual space_config_vector memory_space_config() const override;