diff --git a/src/mess/drivers/comp4.c b/src/mess/drivers/comp4.c
new file mode 100644
index 00000000000..db5a140217d
--- /dev/null
+++ b/src/mess/drivers/comp4.c
@@ -0,0 +1,164 @@
+// license:BSD-3-Clause
+// copyright-holders:hap
+/***************************************************************************
+
+  Milton Bradley Comp IV
+  * TMC0904NL CP0904A (die labeled 4A0970D-04A)
+  
+  This is a handheld Mastermind game; a code-breaking game where the player
+  needs to find out the correct sequence of colours (numbers in our case).
+  It is known as Logic 5 in Europe, and as Pythaugoras in Japan.
+  
+  Press the R key to start, followed by a set of unique numbers and E.
+  Refer to the official manual for more information.
+
+
+  TODO:
+  - write_r doesn't look right, maybe something missing in cpu emulation
+
+***************************************************************************/
+
+#include "emu.h"
+#include "cpu/tms0980/tms0980.h"
+#include "sound/speaker.h"
+
+// master clock is cpu internal, the value below is an approximation
+#define COMP4_CLOCK (250000)
+
+
+class comp4_state : public driver_device
+{
+public:
+	comp4_state(const machine_config &mconfig, device_type type, const char *tag)
+		: driver_device(mconfig, type, tag),
+		m_maincpu(*this, "maincpu"),
+		m_button_matrix(*this, "IN")
+	{ }
+
+	required_device<cpu_device> m_maincpu;
+	required_ioport_array<3> m_button_matrix;
+
+	UINT16 m_o;
+
+	DECLARE_READ8_MEMBER(read_k);
+	DECLARE_WRITE16_MEMBER(write_o);
+	DECLARE_WRITE16_MEMBER(write_r);
+
+	virtual void machine_start();
+};
+
+
+/***************************************************************************
+
+  I/O
+
+***************************************************************************/
+
+READ8_MEMBER(comp4_state::read_k)
+{
+	UINT8 k = 0;
+	
+	if (m_o == 0)
+		k |= m_button_matrix[0]->read();
+	else if (m_o == 1)
+		k |= m_button_matrix[1]->read();
+	else if (m_o == 2)
+		k |= m_button_matrix[2]->read();
+	
+	return k;
+}
+
+WRITE16_MEMBER(comp4_state::write_r)
+{
+	// LEDs?
+}
+
+WRITE16_MEMBER(comp4_state::write_o)
+{
+	// O0-O2: input mux
+	// other bits: some LEDs?
+	m_o = data;
+}
+
+
+
+/***************************************************************************
+
+  Inputs
+
+***************************************************************************/
+
+static INPUT_PORTS_START( comp4 )
+	PORT_START("IN.0")
+	PORT_BIT( 0x01, IP_ACTIVE_HIGH, IPT_BUTTON1 ) PORT_CODE(KEYCODE_R) PORT_CODE(KEYCODE_DEL_PAD) PORT_NAME("R")
+	PORT_BIT( 0x02, IP_ACTIVE_HIGH, IPT_BUTTON2 ) PORT_CODE(KEYCODE_4) PORT_CODE(KEYCODE_4_PAD) PORT_NAME("4")
+	PORT_BIT( 0x04, IP_ACTIVE_HIGH, IPT_BUTTON3 ) PORT_CODE(KEYCODE_1) PORT_CODE(KEYCODE_1_PAD) PORT_NAME("1")
+	PORT_BIT( 0x08, IP_ACTIVE_HIGH, IPT_BUTTON4 ) PORT_CODE(KEYCODE_7) PORT_CODE(KEYCODE_7_PAD) PORT_NAME("7")
+
+	PORT_START("IN.1")
+	PORT_BIT( 0x01, IP_ACTIVE_HIGH, IPT_BUTTON5 ) PORT_CODE(KEYCODE_0) PORT_CODE(KEYCODE_0_PAD) PORT_NAME("0")
+	PORT_BIT( 0x02, IP_ACTIVE_HIGH, IPT_BUTTON6 ) PORT_CODE(KEYCODE_5) PORT_CODE(KEYCODE_5_PAD) PORT_NAME("5")
+	PORT_BIT( 0x04, IP_ACTIVE_HIGH, IPT_BUTTON7 ) PORT_CODE(KEYCODE_2) PORT_CODE(KEYCODE_2_PAD) PORT_NAME("2")
+	PORT_BIT( 0x08, IP_ACTIVE_HIGH, IPT_BUTTON8 ) PORT_CODE(KEYCODE_8) PORT_CODE(KEYCODE_8_PAD) PORT_NAME("8")
+
+	PORT_START("IN.2")
+	PORT_BIT( 0x01, IP_ACTIVE_HIGH, IPT_BUTTON9 ) PORT_CODE(KEYCODE_E) PORT_CODE(KEYCODE_ENTER_PAD) PORT_NAME("E")
+	PORT_BIT( 0x02, IP_ACTIVE_HIGH, IPT_BUTTON10 ) PORT_CODE(KEYCODE_6) PORT_CODE(KEYCODE_6_PAD) PORT_NAME("6")
+	PORT_BIT( 0x04, IP_ACTIVE_HIGH, IPT_BUTTON11 ) PORT_CODE(KEYCODE_3) PORT_CODE(KEYCODE_3_PAD) PORT_NAME("3")
+	PORT_BIT( 0x08, IP_ACTIVE_HIGH, IPT_BUTTON12 ) PORT_CODE(KEYCODE_9) PORT_CODE(KEYCODE_9_PAD) PORT_NAME("9")
+INPUT_PORTS_END
+
+
+
+/***************************************************************************
+
+  Machine Config
+
+***************************************************************************/
+
+void comp4_state::machine_start()
+{
+	m_o = 0;
+	save_item(NAME(m_o));
+}
+
+
+static const UINT16 comp4_output_pla[0x20] =
+{
+	/* O output PLA configuration currently unknown */
+	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f
+};
+
+
+static MACHINE_CONFIG_START( comp4, comp4_state )
+
+	/* basic machine hardware */
+	MCFG_CPU_ADD("maincpu", TMS0970, COMP4_CLOCK)
+	MCFG_TMS1XXX_OUTPUT_PLA(comp4_output_pla)
+	MCFG_TMS1XXX_READ_K(READ8(comp4_state, read_k))
+	MCFG_TMS1XXX_WRITE_O(WRITE16(comp4_state, write_o))
+	MCFG_TMS1XXX_WRITE_R(WRITE16(comp4_state, write_r))
+
+	/* no video! */
+
+	/* no sound! */
+MACHINE_CONFIG_END
+
+
+
+/***************************************************************************
+
+  Game driver(s)
+
+***************************************************************************/
+
+ROM_START( comp4 )
+	ROM_REGION( 0x0800, "maincpu", ROMREGION_ERASE00 )
+	ROM_LOAD( "cp0904a", 0x0000, 0x0400, CRC(c502c8a1) SHA1(f82ff1a85c4849621d32344964d8b2233fc978d0) )
+ROM_END
+
+
+CONS( 1977, comp4, 0, 0, comp4, comp4, driver_device, 0, "Milton Bradley", "Comp IV", GAME_NOT_WORKING | GAME_SUPPORTS_SAVE | GAME_NO_SOUND_HW )
diff --git a/src/mess/mess.lst b/src/mess/mess.lst
index 110903f6dfa..19bf8dbf899 100644
--- a/src/mess/mess.lst
+++ b/src/mess/mess.lst
@@ -296,6 +296,7 @@ intvsrs   // Intellivision (Sears License) - 19??
 intvoice      // Mattel Intellivision + IntelliVoice expansion - 1982
 
 // Milton Bradley
+comp4
 microvsn  // MicroVision - 1979
 simon
 
diff --git a/src/mess/mess.mak b/src/mess/mess.mak
index aa5bec24951..6eaedf44fd4 100644
--- a/src/mess/mess.mak
+++ b/src/mess/mess.mak
@@ -1352,6 +1352,7 @@ $(MESSOBJ)/matsushi.a:          \
 	$(MESS_DRIVERS)/myb3k.o     \
 
 $(MESSOBJ)/mb.a:                \
+	$(MESS_DRIVERS)/comp4.o     \
 	$(MESS_DRIVERS)/microvsn.o  \
 	$(MESS_DRIVERS)/simon.o     \