diff --git a/src/mame/drivers/dorachan.cpp b/src/mame/drivers/dorachan.cpp
index 5012c96dab7..dca16872560 100644
--- a/src/mame/drivers/dorachan.cpp
+++ b/src/mame/drivers/dorachan.cpp
@@ -8,6 +8,13 @@ Similar to Beam Invader
 Todo:
 - discrete sound
 - dips (if any) - bits 5,6,7 of input port 0 ?
+
+Gameplay: run over dots in lower half while avoiding monsters and trees. This draws
+back the red curtain blocking access to top part of the screen. Go through and new dots
+below are worth more points.
+
+It appears that unused bits in port 03 are to operate the discrete sound channels.
+
 */
 
 #include "emu.h"
@@ -19,14 +26,31 @@ class dorachan_state : public driver_device
 {
 public:
 	dorachan_state(const machine_config &mconfig, device_type type, const char *tag)
-		: driver_device(mconfig, type, tag),
-		m_maincpu(*this, "maincpu"),
-		m_screen(*this, "screen"),
-		m_palette(*this, "palette"),
-		m_videoram(*this, "videoram"),
-		m_colors(*this, "colors")
+		: driver_device(mconfig, type, tag)
+		, m_maincpu(*this, "maincpu")
+		, m_screen(*this, "screen")
+		, m_palette(*this, "palette")
+		, m_videoram(*this, "videoram")
+		, m_colors(*this, "colors")
 	{ }
 
+	DECLARE_WRITE8_MEMBER(control_w);
+	DECLARE_WRITE8_MEMBER(protection_w);
+	DECLARE_READ8_MEMBER(protection_r);
+	DECLARE_READ8_MEMBER(v128_r);
+	uint32_t screen_update_dorachan(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect);
+	void dorachan(machine_config &config);
+	void dorachan_io_map(address_map &map);
+	void dorachan_map(address_map &map);
+
+private:
+	// internal state
+	uint8_t m_flip_screen;
+	uint16_t m_prot_value;
+
+	virtual void machine_start() override;
+	virtual void machine_reset() override;
+
 	// devices, memory pointers
 	required_device<cpu_device> m_maincpu;
 	required_device<screen_device> m_screen;
@@ -34,20 +58,6 @@ public:
 
 	required_shared_ptr<uint8_t> m_videoram;
 	required_region_ptr<uint8_t> m_colors;
-
-	// internal state
-	uint8_t m_flip_screen;
-
-	DECLARE_WRITE8_MEMBER(control_w);
-	DECLARE_READ8_MEMBER(protection_r);
-	DECLARE_READ8_MEMBER(v128_r);
-	uint32_t screen_update_dorachan(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect);
-
-	virtual void machine_start() override;
-	virtual void machine_reset() override;
-	void dorachan(machine_config &config);
-	void dorachan_io_map(address_map &map);
-	void dorachan_map(address_map &map);
 };
 
 
@@ -79,11 +89,8 @@ uint32_t dorachan_state::screen_update_dorachan(screen_device &screen, bitmap_rg
 
 		for (int i = 0; i < 8; i++)
 		{
-			uint8_t color = (data & 0x01) ? fore_color : 0;
-			bitmap.pix32(y, x) = m_palette->pen_color(color);
-
-			data = data >> 1;
-			x = x + 1;
+			uint8_t color = BIT(data, i) ? fore_color : 0;
+			bitmap.pix32(y, x++) = m_palette->pen_color(color);
 		}
 	}
 
@@ -98,35 +105,45 @@ uint32_t dorachan_state::screen_update_dorachan(screen_device &screen, bitmap_rg
  *
  *************************************/
 
+WRITE8_MEMBER(dorachan_state::protection_w)
+{
+	// e0 seems like some sort of control byte?
+	// ignore f3 writes, written after every command?
+	if (data != 0xf3)
+	{
+		m_prot_value <<= 8;
+		m_prot_value |= data;
+	}
+}
+
 READ8_MEMBER(dorachan_state::protection_r)
 {
-	uint8_t ret = 0;
-
-	switch (m_maincpu->pcbase())
+	switch (m_prot_value)
 	{
-	case 0x70ce: ret = 0xf2; break;
-	case 0x72a2: ret = 0xd5; break;
-	case 0x72b5: ret = 0xcb; break;
+	case 0xfbf7:
+		return 0xf2;
 
-	default:
-		osd_printf_debug("unhandled $2400 read @ %x\n", m_maincpu->pcbase());
-		break;
+	case 0xf9f7:
+		return 0xd5;
+
+	case 0xf7f4:
+		return 0xcb;
 	}
 
-	return ret;
+	return 0;
 }
 
 READ8_MEMBER(dorachan_state::v128_r)
 {
 	// to avoid resetting (when player 2 starts) bit 0 need to be inverted when screen is flipped
-	return 0xfe | ((m_screen->vpos() >> 7 & 1) ^ m_flip_screen);
+	return 0xfe | (BIT(m_screen->vpos(), 7) ^ m_flip_screen);
 }
 
 WRITE8_MEMBER(dorachan_state::control_w)
 {
 	// d6: flip screen
 	// other: ?
-	m_flip_screen = data >> 6 & 1;
+	m_flip_screen = BIT(data, 6);
 }
 
 
@@ -147,7 +164,7 @@ void dorachan_state::dorachan_io_map(address_map &map)
 {
 	map.global_mask(0xff);
 	map(0x01, 0x01).nopw();
-	map(0x02, 0x02).nopw();
+	map(0x02, 0x02).w(this, FUNC(dorachan_state::protection_w));
 	map(0x03, 0x03).w(this, FUNC(dorachan_state::control_w));
 }
 
@@ -198,11 +215,13 @@ INPUT_PORTS_END
 void dorachan_state::machine_start()
 {
 	save_item(NAME(m_flip_screen));
+	save_item(NAME(m_prot_value));
 }
 
 void dorachan_state::machine_reset()
 {
 	m_flip_screen = 0;
+	m_prot_value = 0;
 }
 
 MACHINE_CONFIG_START(dorachan_state::dorachan)