diff --git a/src/emu/cpu/sm510/sm510.c b/src/emu/cpu/sm510/sm510.c
index ddd6c6f29e1..393f920ce79 100644
--- a/src/emu/cpu/sm510/sm510.c
+++ b/src/emu/cpu/sm510/sm510.c
@@ -6,6 +6,9 @@
   - SM510: x
   - SM511: x
   - SM512: x
+  
+  Other chips that may be in the same family, investigate more when one of
+  them needs to get emulated: SM500, SM530, SM531, ..
 
   References:
   - 1990 Sharp Microcomputers Data Book
@@ -63,6 +66,7 @@ void sm510_base_device::device_start()
 	m_c = 0;
 	m_skip = false;
 	m_w = 0;
+	m_r = 0;
 	m_div = 0;
 	m_1s = false;
 	m_k_active = false;
@@ -72,6 +76,11 @@ void sm510_base_device::device_start()
 	m_bp = false;
 	m_bc = false;
 	m_halt = false;
+	m_melody_rd = 0;
+	m_melody_step_count = 0;
+	m_melody_duty_count = 0;
+	m_melody_duty_index = 0;
+	m_melody_address = 0;
 
 	// register for savestates
 	save_item(NAME(m_stack));
@@ -86,6 +95,7 @@ void sm510_base_device::device_start()
 	save_item(NAME(m_c));
 	save_item(NAME(m_skip));
 	save_item(NAME(m_w));
+	save_item(NAME(m_r));
 	save_item(NAME(m_div));
 	save_item(NAME(m_1s));
 	save_item(NAME(m_k_active));
@@ -95,6 +105,11 @@ void sm510_base_device::device_start()
 	save_item(NAME(m_bp));
 	save_item(NAME(m_bc));
 	save_item(NAME(m_halt));
+	save_item(NAME(m_melody_rd));
+	save_item(NAME(m_melody_step_count));
+	save_item(NAME(m_melody_duty_count));
+	save_item(NAME(m_melody_duty_index));
+	save_item(NAME(m_melody_address));
 
 	// register state for debugger
 	state_add(SM510_PC,  "PC",  m_pc).formatstr("%04X");
@@ -109,8 +124,10 @@ void sm510_base_device::device_start()
 
 	m_icountptr = &m_icount;
 
+	// init peripherals
 	init_divider();
 	init_lcd_driver();
+	init_melody();
 }
 
 
@@ -132,6 +149,7 @@ void sm510_base_device::device_reset()
 	m_bc = false;
 	m_y = 0;
 	
+	m_r = 0;
 	m_write_r(0, 0, 0xff);
 }
 
@@ -175,6 +193,7 @@ TIMER_CALLBACK_MEMBER(sm510_base_device::lcd_timer_cb)
 
 void sm510_base_device::init_lcd_driver()
 {
+	// note: in reality, this timer runs at high frequency off the main divider, strobing one segment at a time
 	m_lcd_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(sm510_base_device::lcd_timer_cb), this));
 	m_lcd_timer->adjust(attotime::from_ticks(0x200, unscaled_clock())); // 64hz default
 }
@@ -182,7 +201,83 @@ void sm510_base_device::init_lcd_driver()
 
 
 //-------------------------------------------------
-//  interrupt/timer
+//  melody controller
+//-------------------------------------------------
+
+void sm510_base_device::clock_melody()
+{
+	if (!m_melody_rom)
+		return;
+
+	// tone cycle table (SM511/SM512 datasheet fig.5)
+	// cmd 0 = cmd, 1 = stop, > 13 = illegal(unknown)
+	static const UINT8 lut_tone_cycles[4*16] =
+	{
+		0, 0, 7, 8, 8, 9, 9, 10,11,11,12,13,14,14, 7*2, 8*2,
+		0, 0, 8, 8, 9, 9, 10,11,11,12,13,13,14,15, 8*2, 8*2,
+		0, 0, 8, 8, 9, 9, 10,10,11,12,12,13,14,15, 8*2, 8*2,
+		0, 0, 8, 9, 9, 10,10,11,11,12,13,14,14,15, 8*2, 9*2
+	};
+	
+	UINT8 cmd = m_melody_rom[m_melody_address] & 0x3f;
+	UINT8 out = 0;
+	
+	// clock duty cycle if tone is active
+	if ((cmd & 0xf) > 1)
+	{
+		out = m_melody_duty_index & m_melody_rd & 1;
+		m_melody_duty_count++;
+		int index = m_melody_duty_index << 4 | (cmd & 0xf);
+		int shift = ~cmd >> 4 & 1; // OCT
+
+		if (m_melody_duty_count >= (lut_tone_cycles[index] << shift))
+		{
+			m_melody_duty_count = 0;
+			m_melody_duty_index = (m_melody_duty_index + 1) & 3;
+		}
+	}
+	else if ((cmd & 0xf) == 1)
+	{
+		// rest tell signal
+		m_melody_rd |= 2;
+	}
+	
+	// clock time base on F8(d7)
+	if ((m_div & 0x7f) == 0)
+	{
+		UINT8 mask = (cmd & 0x20) ? 0x1f : 0x0f;
+		m_melody_step_count = (m_melody_step_count + 1) & mask;
+
+		if (m_melody_step_count == 0)
+			m_melody_address++;
+	}
+	
+	// output to R pin
+	if (out != m_r)
+	{
+		m_write_r(0, out, 0xff);
+		m_r = out;
+	}
+}
+
+void sm510_base_device::init_melody()
+{
+	if (!m_melody_rom)
+		return;
+
+	// verify melody rom
+	for (int i = 0; i < 0x100; i++)
+	{
+		UINT8 data = m_melody_rom[i];
+		if (data & 0xc0 || (data & 0x0f) > 13)
+			logerror("%s unknown melody ROM data $%02X at $%02X\n", tag(), data, i);
+	}
+}
+
+
+
+//-------------------------------------------------
+//  interrupt/divider
 //-------------------------------------------------
 
 bool sm510_base_device::wake_me_up()
@@ -213,28 +308,19 @@ void sm510_base_device::execute_set_input(int line, int state)
 
 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;
-	
+	m_div = (m_div + 1) & 0x7fff;
+
 	// 1S signal on overflow(falling edge of f1)
 	if (m_div == 0)
 		m_1s = true;
-
-	// 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()));
+	
+	clock_melody();
 }
 
 void sm510_base_device::init_divider()
 {
 	m_div_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(sm510_base_device::div_timer_cb), this));
-	reset_divider();
+	m_div_timer->adjust(attotime::from_ticks(1, unscaled_clock()), 0, attotime::from_ticks(1, unscaled_clock()));
 }
 
 
diff --git a/src/emu/cpu/sm510/sm510.h b/src/emu/cpu/sm510/sm510.h
index a25deb938b0..bf691650547 100644
--- a/src/emu/cpu/sm510/sm510.h
+++ b/src/emu/cpu/sm510/sm510.h
@@ -77,6 +77,7 @@ public:
 		, m_stack_levels(stack_levels)
 		, m_lcd_ram_a(*this, "lcd_ram_a"), m_lcd_ram_b(*this, "lcd_ram_b"), m_lcd_ram_c(*this, "lcd_ram_c")
 		, m_write_sega(*this), m_write_segb(*this), m_write_segc(*this), m_write_segbs(*this)
+		, m_melody_rom(*this, "music")
 		, m_read_k(*this)
 		, m_read_ba(*this), m_read_b(*this)
 		, m_write_s(*this)
@@ -140,6 +141,7 @@ protected:
 	UINT8 m_c;
 	bool m_skip;
 	UINT8 m_w;
+	UINT8 m_r;
 	bool m_k_active;
 	bool m_halt;
 
@@ -156,16 +158,27 @@ protected:
 	TIMER_CALLBACK_MEMBER(lcd_timer_cb);
 	virtual void init_lcd_driver();
 
-	// clock divider
+	// melody controller
+	optional_region_ptr<UINT8> m_melody_rom;
+	UINT8 m_melody_rd;
+	UINT8 m_melody_step_count;
+	UINT8 m_melody_duty_count;
+	UINT8 m_melody_duty_index;
+	UINT8 m_melody_address;
+
+	void clock_melody();
+	void init_melody();
+
+	// interrupt/divider
 	emu_timer *m_div_timer;
 	UINT16 m_div;
 	bool m_1s;
 
-	TIMER_CALLBACK_MEMBER(div_timer_cb);
 	bool wake_me_up();
-	virtual void reset_divider();
-	void init_divider();
-
+	virtual void reset_divider() { m_div = 0; }
+	virtual void init_divider();
+	virtual TIMER_CALLBACK_MEMBER(div_timer_cb);
+	
 	// other i/o handlers
 	devcb_read8 m_read_k;
 	devcb_read_line m_read_ba;
@@ -175,7 +188,7 @@ protected:
 
 	// misc internal helpers
 	void increment_pc();
-	virtual void get_opcode_param() { } // -> child class
+	virtual void get_opcode_param() { }
 	virtual void update_w_latch() { }
 
 	UINT8 ram_r();
@@ -264,6 +277,11 @@ protected:
 	virtual void get_opcode_param();
 	
 	virtual void update_w_latch() { m_write_s(0, m_w, 0xff); } // W is connected directly to S
+	
+	// divider
+	virtual TIMER_CALLBACK_MEMBER(div_timer_cb);
+	virtual void reset_divider();
+	virtual void init_divider();
 };
 
 
diff --git a/src/emu/cpu/sm510/sm510core.c b/src/emu/cpu/sm510/sm510core.c
index 0ac9d7d3caf..cbdb4c37edd 100644
--- a/src/emu/cpu/sm510/sm510core.c
+++ b/src/emu/cpu/sm510/sm510core.c
@@ -43,6 +43,40 @@ offs_t sm510_device::disasm_disassemble(char *buffer, offs_t pc, const UINT8 *op
 }
 
 
+
+
+//-------------------------------------------------
+//  divider
+//-------------------------------------------------
+
+TIMER_CALLBACK_MEMBER(sm510_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;
+
+	// schedule next timeout
+	m_div_timer->adjust(attotime::from_ticks(0x800, unscaled_clock()));
+}
+
+void sm510_device::reset_divider()
+{
+	m_div = 0;
+	m_div_timer->adjust(attotime::from_ticks(0x800, unscaled_clock()));
+}
+
+void sm510_device::init_divider()
+{
+	m_div_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(sm510_device::div_timer_cb), this));
+	reset_divider();
+}
+
+
+
 //-------------------------------------------------
 //  execute
 //-------------------------------------------------
diff --git a/src/emu/cpu/sm510/sm510op.c b/src/emu/cpu/sm510/sm510op.c
index 16aa00dc507..f6c097932d3 100644
--- a/src/emu/cpu/sm510/sm510op.c
+++ b/src/emu/cpu/sm510/sm510op.c
@@ -248,7 +248,11 @@ void sm510_base_device::op_atfc()
 void sm510_base_device::op_atr()
 {
 	// ATR: output ACC to R
-	m_write_r(0, m_acc & 3, 0xff);
+	if (m_r != (m_acc & 3))
+	{
+		m_r = m_acc & 3;
+		m_write_r(0, m_r, 0xff);
+	}
 }
 
 
@@ -387,26 +391,28 @@ void sm510_base_device::op_sm()
 
 void sm510_base_device::op_pre()
 {
-	// PRE x: x
-	op_illegal();
+	// PRE x: melody ROM pointer preset
+	m_melody_address = m_param;
+	m_melody_step_count = 0;
 }
 
 void sm510_base_device::op_sme()
 {
-	// SME: x
-	op_illegal();
+	// SME: set melody enable
+	m_melody_rd |= 1;
 }
 
 void sm510_base_device::op_rme()
 {
-	// RME: x
-	op_illegal();
+	// RME: reset melody enable
+	m_melody_rd &= ~1;
 }
 
 void sm510_base_device::op_tmel()
 {
-	// TMEL: x
-	op_illegal();
+	// TMEL: skip next if rest signal is set, reset it
+	m_skip = ((m_melody_rd & 2) != 0);
+	m_melody_rd &= ~2;
 }
 
 
diff --git a/src/emu/cpu/sm510/sm511core.c b/src/emu/cpu/sm510/sm511core.c
index 87c4ad72bc8..07f88152e27 100644
--- a/src/emu/cpu/sm510/sm511core.c
+++ b/src/emu/cpu/sm510/sm511core.c
@@ -64,7 +64,7 @@ sm512_device::sm512_device(const machine_config &mconfig, const char *tag, devic
 void sm511_device::get_opcode_param()
 {
 	// LBL, PRE, TL, TML and prefix opcodes are 2 bytes
-	if ((m_op >= 0x5f && m_op <= 0x61) || (m_op & 0xf0) == 0x70 || (m_op & 0xfc) == 0x68)
+	if (m_op == 0x01 || (m_op >= 0x5f && m_op <= 0x61) || (m_op & 0xf0) == 0x70 || (m_op & 0xfc) == 0x68)
 	{
 		m_icount--;
 		m_param = m_program->read_byte(m_pc);
@@ -102,6 +102,7 @@ void sm511_device::execute_one()
 			switch (m_op)
 			{
 		case 0x00: op_rot(); break;
+//		case 0x01: op_xxx(); break; // ?
 		case 0x02: op_sbm(); break;
 		case 0x03: op_atpl(); break;
 		case 0x08: op_add(); break;
@@ -129,8 +130,6 @@ void sm511_device::execute_one()
 //		case 0x65: op_idiv(); break;
 		case 0x66: op_rc(); break;
 		case 0x67: op_sc(); break;
-//		case 0x68: op_tf1(); break;
-//		case 0x69: op_tf4(); break;
 		case 0x6c: op_decb(); break;
 		case 0x6d: op_ptw(); break;
 		case 0x6e: op_rtn0(); break;
diff --git a/src/mess/drivers/hh_sm510.c b/src/mess/drivers/hh_sm510.c
index f6d0c51d5e3..ff7e4b7b9cc 100644
--- a/src/mess/drivers/hh_sm510.c
+++ b/src/mess/drivers/hh_sm510.c
@@ -261,10 +261,10 @@ static INPUT_PORTS_START( ktmnt )
 	PORT_BIT( 0x08, IP_ACTIVE_HIGH, IPT_JOYSTICK_RIGHT ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL)
 
 	PORT_START("IN.1")
-	PORT_BIT( 0x01, IP_ACTIVE_HIGH, IPT_BUTTON1 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL)
-	PORT_BIT( 0x02, IP_ACTIVE_HIGH, IPT_BUTTON2 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL)
-	PORT_BIT( 0x04, IP_ACTIVE_HIGH, IPT_BUTTON3 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL)
-	PORT_BIT( 0x08, IP_ACTIVE_HIGH, IPT_BUTTON4 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL)
+	PORT_BIT( 0x01, IP_ACTIVE_HIGH, IPT_BUTTON1 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL) // game select
+	PORT_BIT( 0x02, IP_ACTIVE_HIGH, IPT_BUTTON2 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL) // sound on/off
+	PORT_BIT( 0x04, IP_ACTIVE_HIGH, IPT_BUTTON3 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL) // off
+	PORT_BIT( 0x08, IP_ACTIVE_HIGH, IPT_BUTTON4 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL) // on/start
 
 	PORT_START("IN.2")
 	PORT_BIT( 0x01, IP_ACTIVE_HIGH, IPT_BUTTON5 ) PORT_CHANGED_MEMBER(DEVICE_SELF, hh_sm510_state, input_changed, NULL)
@@ -381,8 +381,10 @@ ROM_END
 
 ROM_START( ktmnt )
 	ROM_REGION( 0x1000, "maincpu", 0 )
-	ROM_LOAD( "kms_73b_774.music", 0x0000, 0x100, CRC(8270d626) SHA1(bd91ca1d5cd7e2a62eef05c0033b19dcdbe441ca) ) //todo
 	ROM_LOAD( "kms_73b_774.prog", 0x0000, 0x1000, CRC(a1064f87) SHA1(92156c35fbbb414007ee6804fe635128a741d5f1) )
+
+	ROM_REGION( 0x100, "maincpu:music", 0 )
+	ROM_LOAD( "kms_73b_774.music", 0x000, 0x100, CRC(8270d626) SHA1(bd91ca1d5cd7e2a62eef05c0033b19dcdbe441ca) )
 ROM_END