diff --git a/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj b/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
index 58dd4df88e..92a232e83c 100644
--- a/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
+++ b/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
@@ -643,6 +643,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper213.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper214.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper218.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\Mapper220.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper221.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper222.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper225.cs" />
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/Mapper220.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/Mapper220.cs
new file mode 100644
index 0000000000..bc8f4c5682
--- /dev/null
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/Mapper220.cs
@@ -0,0 +1,98 @@
+using BizHawk.Common;
+using BizHawk.Common.NumberExtensions;
+
+namespace BizHawk.Emulation.Cores.Nintendo.NES
+{
+	// Ported from FCEUX
+	public sealed class Mapper220 : NES.NESBoardBase
+	{
+		private ByteBuffer reg = new ByteBuffer(8);
+		private int prg_mask_2k;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "UNIF_UNL-KS7057":
+				case "MAPPER220":
+					break;
+				default:
+					return false;
+			}
+
+			prg_mask_2k = Cart.prg_size / 2 - 1;
+			return true;
+		}
+
+		public override void Dispose()
+		{
+			reg.Dispose();
+			base.Dispose();
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			ser.Sync("reg", ref reg);
+			base.SyncState(ser);
+		}
+
+		public override void WritePRG(int addr, byte value)
+		{
+			addr += 0x8000;
+			switch (addr & 0xF003)
+			{
+				case 0x8000:
+				case 0x8001:
+				case 0x8002:
+				case 0x8003:
+				case 0x9000:
+				case 0x9001:
+				case 0x9002:
+				case 0x9003:
+					SetMirrorType(value.Bit(0) ? EMirrorType.Vertical : EMirrorType.Horizontal);
+					break;
+				case 0xB000: reg[0] = (byte)((reg[0] & 0xF0) | (value & 0x0F)); break;
+				case 0xB001: reg[0] = (byte)((reg[0] & 0x0F) | (value << 4)); break;
+				case 0xB002: reg[1] = (byte)((reg[1] & 0xF0) | (value & 0x0F)); break;
+				case 0xB003: reg[1] = (byte)((reg[1] & 0x0F) | (value << 4)); break;
+				case 0xC000: reg[2] = (byte)((reg[2] & 0xF0) | (value & 0x0F)); break;
+				case 0xC001: reg[2] = (byte)((reg[2] & 0x0F) | (value << 4)); break;
+				case 0xC002: reg[3] = (byte)((reg[3] & 0xF0) | (value & 0x0F)); break;
+				case 0xC003: reg[3] = (byte)((reg[3] & 0x0F) | (value << 4)); break;
+				case 0xD000: reg[4] = (byte)((reg[4] & 0xF0) | (value & 0x0F)); break;
+				case 0xD001: reg[4] = (byte)((reg[4] & 0x0F) | (value << 4)); break;
+				case 0xD002: reg[5] = (byte)((reg[5] & 0xF0) | (value & 0x0F)); break;
+				case 0xD003: reg[5] = (byte)((reg[5] & 0x0F) | (value << 4)); break;
+				case 0xE000: reg[6] = (byte)((reg[6] & 0xF0) | (value & 0x0F)); break;
+				case 0xE001: reg[6] = (byte)((reg[6] & 0x0F) | (value << 4)); break;
+				case 0xE002: reg[7] = (byte)((reg[7] & 0xF0) | (value & 0x0F)); break;
+				case 0xE003: reg[7] = (byte)((reg[7] & 0x0F) | (value << 4)); break;
+			}
+		}
+
+		public override byte ReadWRAM(int addr)
+		{
+			int i = ((addr >> 11) & 3) + 4;
+			int bank = reg[i] & prg_mask_2k;
+			return ROM[(bank << 11) + (addr & 0x7FF)];
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			if (addr < 0x2000)
+			{
+				int i = (addr >> 11) & 3;
+				int bank = reg[i] & prg_mask_2k;
+				return ROM[(bank << 11) + (addr & 0x7FF)];
+			}
+			else if (addr < 0x4000)
+			{
+				return ROM[0x1A000 /* bank 0xd*/ + (addr & 0x1FFF)];
+			}
+			else
+			{
+				return ROM[0x1C000 /* bank 7*/ + (addr & 0x3FFF)];
+			}
+		}
+	}
+}