diff --git a/src/emu/cpu/sm510/sm510.c b/src/emu/cpu/sm510/sm510.c
index 2968335b68a..2da7d34d19f 100644
--- a/src/emu/cpu/sm510/sm510.c
+++ b/src/emu/cpu/sm510/sm510.c
@@ -36,8 +36,13 @@ void sm510_base_device::device_start()
 	m_prgmask = (1 << m_prgwidth) - 1;
 	m_datamask = (1 << m_datawidth) - 1;
 
+	m_div_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(sm510_base_device::div_timer_cb), this));
+	reset_divider();
+
 	// resolve callbacks
 	m_read_k.resolve_safe(0);
+	m_read_ba.resolve_safe(1);
+	m_read_b.resolve_safe(1);
 	m_write_s.resolve_safe();
 
 	// zerofill
@@ -53,9 +58,11 @@ void sm510_base_device::device_start()
 	m_c = 0;
 	m_skip = false;
 	m_w = 0;
-	m_div = 0;
-	m_bdc = false;
-	m_cend = false;
+//	m_div = 0;
+	m_1s = false;
+	m_bp = false;
+	m_bc = false;
+	m_halt = false;
 
 	// register for savestates
 	save_item(NAME(m_stack));
@@ -71,8 +78,10 @@ void sm510_base_device::device_start()
 	save_item(NAME(m_skip));
 	save_item(NAME(m_w));
 	save_item(NAME(m_div));
-	save_item(NAME(m_bdc));
-	save_item(NAME(m_cend));
+	save_item(NAME(m_1s));
+	save_item(NAME(m_bp));
+	save_item(NAME(m_bc));
+	save_item(NAME(m_halt));
 
 	// register state for debugger
 	state_add(SM510_PC,  "PC",  m_pc).formatstr("%04X");
@@ -97,11 +106,66 @@ void sm510_base_device::device_start()
 void sm510_base_device::device_reset()
 {
 	m_skip = false;
-	m_bdc = false;
-	m_cend = false;
+	m_halt = false;
 	m_op = m_prev_op = 0;
 	do_branch(3, 7, 0);
 	m_prev_pc = m_pc;
+	
+	// lcd is on (Bp on, BC off)
+	m_bp = true;
+	m_bc = false;
+	
+	// y=0(bs), r=0
+}
+
+
+
+//-------------------------------------------------
+//  interrupt/timer
+//-------------------------------------------------
+
+void sm510_base_device::wake_me_up()
+{
+	// in halt mode, wake up after 1S signal or K input
+	if (m_halt)
+	{
+		m_halt = false;
+		do_branch(1, 0, 0);
+		
+		standard_irq_callback(0);
+
+		// note: official doc warns that Bl/Bm and the stack are undefined
+		// after waking up, but we leave it unchanged
+	}
+}
+
+void sm510_base_device::execute_set_input(int line, int state)
+{
+	if (line != 0)
+		return;
+}
+
+TIMER_CALLBACK_MEMBER(sm510_base_device::div_timer_cb)
+{
+	// no need to increment it by 1 everytime, since only the
+	// highest bits are accessible
+	m_div = (m_div + 0x800) & 0x7fff;
+	
+	// 1S signal on overflow(falling edge of f1)
+	if (m_div == 0)
+	{
+		m_1s = true;
+		wake_me_up();
+	}
+
+	// schedule next timeout
+	m_div_timer->adjust(attotime::from_ticks(0x800, unscaled_clock()));
+}
+
+void sm510_base_device::reset_divider()
+{
+	m_div = 0;
+	m_div_timer->adjust(attotime::from_ticks(0x800, unscaled_clock()));
 }
 
 
@@ -120,6 +184,13 @@ void sm510_base_device::increment_pc()
 
 void sm510_base_device::execute_run()
 {
+	// nothing to do if in halt mode
+	if (m_halt)
+	{
+		m_icount = 0;
+		return;
+	}
+	
 	while (m_icount > 0)
 	{
 		// remember previous state
diff --git a/src/emu/cpu/sm510/sm510.h b/src/emu/cpu/sm510/sm510.h
index 7af7f1a7542..e8d345d2389 100644
--- a/src/emu/cpu/sm510/sm510.h
+++ b/src/emu/cpu/sm510/sm510.h
@@ -14,10 +14,18 @@
 
 // I/O ports setup
 
-// 4-bit K input port
+// 4-bit K input port (pull-down)
 #define MCFG_SM510_READ_K_CB(_devcb) \
 	sm510_base_device::set_read_k_callback(*device, DEVCB_##_devcb);
 
+// 1-bit BA input pin (pull-up)
+#define MCFG_SM510_READ_BA_CB(_devcb) \
+	sm510_base_device::set_read_ba_callback(*device, DEVCB_##_devcb);
+
+// 1-bit B(beta) input pin (pull-up)
+#define MCFG_SM510_READ_B_CB(_devcb) \
+	sm510_base_device::set_read_b_callback(*device, DEVCB_##_devcb);
+
 // 8-bit S strobe output port
 #define MCFG_SM510_WRITE_S_CB(_devcb) \
 	sm510_base_device::set_write_s_callback(*device, DEVCB_##_devcb);
@@ -43,11 +51,15 @@ public:
 		, m_datawidth(datawidth)
 		, m_stack_levels(stack_levels)
 		, m_read_k(*this)
+		, m_read_ba(*this)
+		, m_read_b(*this)
 		, m_write_s(*this)
 	{ }
 
 	// static configuration helpers
 	template<class _Object> static devcb_base &set_read_k_callback(device_t &device, _Object object) { return downcast<sm510_base_device &>(device).m_read_k.set_callback(object); }
+	template<class _Object> static devcb_base &set_read_ba_callback(device_t &device, _Object object) { return downcast<sm510_base_device &>(device).m_read_ba.set_callback(object); }
+	template<class _Object> static devcb_base &set_read_b_callback(device_t &device, _Object object) { return downcast<sm510_base_device &>(device).m_read_b.set_callback(object); }
 	template<class _Object> static devcb_base &set_write_s_callback(device_t &device, _Object object) { return downcast<sm510_base_device &>(device).m_write_s.set_callback(object); }
 
 protected:
@@ -61,7 +73,7 @@ protected:
 	virtual UINT32 execute_min_cycles() const { return 1; }
 	virtual UINT32 execute_max_cycles() const { return 2; }
 	virtual UINT32 execute_input_lines() const { return 1; }
-	//virtual void execute_set_input(int line, int state);
+	virtual void execute_set_input(int line, int state);
 	virtual void execute_run();
 	virtual void execute_one() { } // -> child class
 
@@ -89,6 +101,7 @@ protected:
 	int m_stack_levels;
 	UINT16 m_stack[2];
 	int m_icount;
+	emu_timer *m_div_timer;
 	
 	UINT8 m_acc;
 	UINT8 m_bl;
@@ -97,15 +110,22 @@ protected:
 	bool m_skip;
 	UINT8 m_w;
 	UINT16 m_div;
-	bool m_bdc;
-	bool m_cend;
+	bool m_1s;
+	bool m_bp;
+	bool m_bc;
+	bool m_halt;
 
 	// i/o handlers
-	devcb_read16 m_read_k;
+	devcb_read8 m_read_k;
+	devcb_read_line m_read_ba;
+	devcb_read_line m_read_b;
 	devcb_write8 m_write_s;
 
 	// misc internal helpers
 	void increment_pc();
+	TIMER_CALLBACK_MEMBER(div_timer_cb);
+	void wake_me_up();
+	virtual void reset_divider();
 	virtual void get_opcode_param() { } // -> child class
 
 	UINT8 ram_r();
diff --git a/src/emu/cpu/sm510/sm510op.c b/src/emu/cpu/sm510/sm510op.c
index 0e3238e1739..b1391a7da8f 100644
--- a/src/emu/cpu/sm510/sm510op.c
+++ b/src/emu/cpu/sm510/sm510op.c
@@ -161,7 +161,7 @@ void sm510_base_device::op_exc()
 void sm510_base_device::op_bdc()
 {
 	// BDC: enable LCD bleeder current with C
-	m_bdc = (m_c != 0);
+	m_bc = (m_c != 0);
 }
 
 void sm510_base_device::op_exci()
@@ -217,8 +217,8 @@ void sm510_base_device::op_kta()
 
 void sm510_base_device::op_atbp()
 {
-	// ATBP: output ACC to BP
-	op_illegal();
+	// ATBP: output ACC to BP(internal LCD backplate signal)
+	m_bp = ((m_acc & 1) != 0);
 }
 
 void sm510_base_device::op_atl()
@@ -296,8 +296,8 @@ void sm510_base_device::op_sc()
 
 void sm510_base_device::op_tb()
 {
-	// TB: x
-	op_illegal();
+	// TB: skip next if B(beta) pin is set
+	m_skip = (m_read_b() != 0);
 }
 
 void sm510_base_device::op_tc()
@@ -326,32 +326,33 @@ void sm510_base_device::op_ta0()
 
 void sm510_base_device::op_tabl()
 {
-	// TABL: skip next of ACC equals BL
+	// TABL: skip next if ACC equals BL
 	m_skip = (m_acc == m_bl);
 }
 
 void sm510_base_device::op_tis()
 {
-	// TIS: x
-	op_illegal();
+	// TIS: skip next if 1S(gamma flag) is clear, reset it after
+	m_skip = !m_1s;
+	m_1s = false;
 }
 
 void sm510_base_device::op_tal()
 {
-	// TAL: x
-	op_illegal();
+	// TAL: skip next if BA pin is set
+	m_skip = (m_read_ba() != 0);
 }
 
 void sm510_base_device::op_tf1()
 {
-	// TF1: x
-	op_illegal();
+	// TF1: skip next if divider F1(d14) is set
+	m_skip = ((m_div & 0x4000) != 0);
 }
 
 void sm510_base_device::op_tf4()
 {
-	// TF4: x
-	op_illegal();
+	// TF4: skip next if divider F4(d11) is set
+	m_skip = ((m_div & 0x0800) != 0);
 }
 
 
@@ -379,14 +380,14 @@ void sm510_base_device::op_skip()
 
 void sm510_base_device::op_cend()
 {
-	// CEND: stop clock
-	m_cend = true;
+	// CEND: stop clock (halt the cpu and go into low-power mode)
+	m_halt = true;
 }
 
 void sm510_base_device::op_idiv()
 {
 	// IDIV: reset divider
-	m_div = 0;
+	reset_divider();
 }
 
 void sm510_base_device::op_illegal()