diff --git a/src/mame/drivers/tk635.cpp b/src/mame/drivers/tk635.cpp
index 7ef69bd3637..996f63e094f 100644
--- a/src/mame/drivers/tk635.cpp
+++ b/src/mame/drivers/tk635.cpp
@@ -19,7 +19,6 @@
 
 	Notes:
 	- Identical to the Qume QVT-72 Plus?
-	- Character shape defintions start at 0x20000 in the ROM
 
 	TODO:
 	- Everything
@@ -36,7 +35,11 @@ class tk635_state : public driver_device
 public:
 	tk635_state(const machine_config &mconfig, device_type type, const char *tag)
 		: driver_device(mconfig, type, tag),
-		m_maincpu(*this, "maincpu")
+		m_maincpu(*this, "maincpu"),
+		m_ram(*this, "ram"),
+		m_charram(*this, "charram"),
+		m_nmi_enable(false),
+		m_voffset(0)
 	{ }
 
 	void tk635(machine_config &config);
@@ -47,37 +50,139 @@ protected:
 
 private:
 	required_device<cpu_device> m_maincpu;
+	required_shared_ptr<u8> m_ram;
+	required_shared_ptr<u8> m_charram;
 
 	void mem_map(address_map &map);
 	void io_map(address_map &map);
 
 	uint32_t screen_update(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect);
+	void vblank_w(int state);
+
+	uint8_t unk_00_r();
+	void voffset_lsb_w(uint8_t data);
+	void voffset_msb_w(uint8_t data);
+	uint8_t unk_11_r();
+	uint8_t unk_19_r();
+	void unk_f0_w(uint8_t data);
+
+	bool m_nmi_enable;
+	uint16_t m_voffset;
 };
 
 void tk635_state::mem_map(address_map &map)
 {
-	map(0x00000, 0x1ffff).ram();
+	map(0x00000, 0x1ffff).ram().share("ram");
+	map(0x20000, 0x23fff).ram().share("charram");
 	map(0xc0000, 0xfffff).rom().region("maincpu", 0);
 }
 
 void tk635_state::io_map(address_map &map)
 {
+	map(0x00, 0x00).r(FUNC(tk635_state::unk_00_r));
+	map(0x04, 0x04).w(FUNC(tk635_state::voffset_lsb_w));
+	map(0x05, 0x05).w(FUNC(tk635_state::voffset_msb_w));
+	map(0x11, 0x11).r(FUNC(tk635_state::unk_11_r));
+//	map(0x13, 0x13).ram(); // host port
+	map(0x19, 0x19).r(FUNC(tk635_state::unk_19_r));
+//	map(0x1b, 0x1b).ram(); // aux port
+	map(0xf0, 0xf0).w(FUNC(tk635_state::unk_f0_w));
 }
 
 static INPUT_PORTS_START( tk635 )
 INPUT_PORTS_END
 
+static const gfx_layout char_layout_8x16 =
+{
+	8, 16,
+	512,
+	1,
+	{ 0 },
+	{ STEP8(0, 1) },
+	{ STEP16(0, 8) },
+	8*32
+};
+
+static GFXDECODE_START(chars)
+	GFXDECODE_RAM("charram", 0, char_layout_8x16, 0, 1)
+GFXDECODE_END
+
 uint32_t tk635_state::screen_update(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect)
 {
+	for (int y = 0; y < 26; y++)
+	{
+		for (int x = 0; x < 132; x++)
+		{
+			uint8_t code = m_ram[(0x10000 | m_voffset) + (y * 132) + x];
+
+			// draw 16 lines
+			for (int i = 0; i < 16; i++)
+			{
+				uint8_t data = m_charram[(code << 5) + i];
+
+				// 8 pixels of the character
+				for (int p = 0; p < 8; p++)
+					bitmap.pix32(y * 16 + i, x * 9 + p) = BIT(data, 7 - p) ? rgb_t::white() : rgb_t::black();
+
+				// 9th pixel empty
+				bitmap.pix32(y * 16 + i, x * 9 + 8) = rgb_t::black();
+			}
+		}
+	}
+
 	return 0;
 }
 
+void tk635_state::vblank_w(int state)
+{
+	if (state == 1 && m_nmi_enable)
+		m_maincpu->pulse_input_line(INPUT_LINE_NMI, attotime::zero);
+}
+
+uint8_t tk635_state::unk_00_r()
+{
+	logerror("unk_00_r: %02x\n", 0x10);
+	return 0x10;
+}
+
+void tk635_state::voffset_lsb_w(uint8_t data)
+{
+	m_voffset = (m_voffset & 0xff00) | data;
+}
+
+void tk635_state::voffset_msb_w(uint8_t data)
+{
+	m_voffset = (data << 8) | (m_voffset & 0x00ff);
+}
+
+uint8_t tk635_state::unk_11_r()
+{
+	logerror("unk_11_r: %02x\n", 0x09);
+	return 0x09;
+}
+
+uint8_t tk635_state::unk_19_r()
+{
+	logerror("unk_19_r: %02x\n", 0x09);
+	return 0x09;
+}
+
+void tk635_state::unk_f0_w(uint8_t data)
+{
+	logerror("unk_f0_w: %02x\n", data);
+	m_nmi_enable = true;
+}
+
 void tk635_state::machine_start()
 {
+	// register for save states
+	save_item(NAME(m_nmi_enable));
+	save_item(NAME(m_voffset));
 }
 
 void tk635_state::machine_reset()
 {
+	m_nmi_enable = false;
 }
 
 void tk635_state::tk635(machine_config &config)
@@ -90,10 +195,13 @@ void tk635_state::tk635(machine_config &config)
 	screen.set_refresh_hz(70);
 	screen.set_vblank_time(ATTOSECONDS_IN_USEC(2500)); // not accurate
 	screen.set_screen_update(FUNC(tk635_state::screen_update));
-	screen.set_size(800, 600);
-	screen.set_visarea(0, 800-1, 0, 600-1);
+	screen.set_size(1188, 416);
+	screen.set_visarea(0, 1188-1, 0, 416-1);
+	screen.screen_vblank().set(FUNC(tk635_state::vblank_w));
 
 	PALETTE(config, "palette").set_entries(16);
+
+	GFXDECODE(config, "gfxdecode", "palette", chars);
 }
 
 ROM_START( tk635 )
@@ -101,4 +209,4 @@ ROM_START( tk635 )
 	ROM_LOAD("fw_v0_23.bin", 0x00000, 0x40000, CRC(bec6fdae) SHA1(37dc46f6b761d874bd1627a1137bc4082e364698))
 ROM_END
 
-COMP( 199?, tk635, 0, 0, tk635, tk635, tk635_state, empty_init, "Termtek", "TK-635", MACHINE_IS_SKELETON )
+COMP( 199?, tk635, 0, 0, tk635, tk635, tk635_state, empty_init, "Termtek", "TK-635", MACHINE_NOT_WORKING | MACHINE_NO_SOUND | MACHINE_SUPPORTS_SAVE )