diff --git a/BizHawk.Emulation/BizHawk.Emulation.csproj b/BizHawk.Emulation/BizHawk.Emulation.csproj
index 47679139e5..1cd7d3df26 100644
--- a/BizHawk.Emulation/BizHawk.Emulation.csproj
+++ b/BizHawk.Emulation/BizHawk.Emulation.csproj
@@ -158,6 +158,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper090.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper107.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper116.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\Mapper120.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper164.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper176.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper178.cs" />
diff --git a/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/Mapper120.cs b/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/Mapper120.cs
new file mode 100644
index 0000000000..e72fb66ebf
--- /dev/null
+++ b/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/Mapper120.cs
@@ -0,0 +1,51 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Consoles.Nintendo
+{
+	class Mapper120 : NES.NESBoardBase
+	{
+		//Used by Tobidase Daisakusen (FDS Conversion).  Undocumented by Disch docs, this implementation is based on FCEUX
+		
+		byte prg_reg;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "MAPPER120":
+					break;
+				default:
+					return false;
+			}
+			SetMirrorType(EMirrorType.Vertical);
+			return true;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			ser.Sync("prg_reg", ref prg_reg);
+			base.SyncState(ser);
+		}
+
+		public override void WriteEXP(int addr, byte value)
+		{
+			if (addr == 0x01FF)
+			{
+				prg_reg = (byte)(value & 0x07);
+			}
+		}
+
+		public override byte ReadWRAM(int addr)
+		{
+			return ROM[((prg_reg & 7) * 0x2000) + (addr & 0x1FFF)];
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			return ROM[0x10000 + addr];
+		}
+	}
+}