diff --git a/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/MMC3_family/Mapper205.cs b/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/MMC3_family/Mapper205.cs
new file mode 100644
index 0000000000..dfc1d3d9c0
--- /dev/null
+++ b/BizHawk.Emulation/Consoles/Nintendo/NES/Boards/MMC3_family/Mapper205.cs
@@ -0,0 +1,121 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Consoles.Nintendo
+{
+	class Mapper205 : MMC3Board_Base
+	{
+		//Mapper 205 info: http://wiki.nesdev.com/w/index.php/INES_Mapper_205
+
+		int block;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			//analyze board type
+			switch (Cart.board_type)
+			{
+				case "MAPPER205":
+					break;
+				default:
+					return false;
+			}
+
+			block = 0;
+
+			BaseSetup();
+			return true;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			ser.Sync("mode", ref block);
+			base.SyncState(ser);
+		}
+
+		public override void WritePPU(int addr, byte value)
+		{
+			if (addr < 0x2000)
+			{
+				block = value & 0x03;
+			}
+
+			base.WritePPU(addr, value);
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			int bank_8k = Get_PRGBank_8K(addr);
+			bank_8k &= prg_mask;
+
+			switch (block)
+			{
+				case 0:
+					bank_8k &= 0x1F;
+					bank_8k |= 0x00;
+					break;
+				case 1:
+					bank_8k &= 0x1F;
+					bank_8k |= 0x10;
+					break;
+				case 2:
+					bank_8k &= 0x0F;
+					bank_8k |= 0x20;
+					break;
+				case 3:
+					bank_8k &= 0x0F;
+					bank_8k |= 0x30;
+					break;
+			}
+
+			addr = (bank_8k << 13) | (addr & 0x1FFF);
+			return ROM[addr];
+		}
+
+		int MapCHR(int addr)
+		{
+			int bank_1k = Get_CHRBank_1K(addr);
+			bank_1k &= chr_mask;
+			switch (bank_1k)
+			{
+				case 0:
+					bank_1k &= 0xFF;
+					bank_1k |= 0x00;
+					break;
+				case 1:
+					bank_1k &= 0xFF;
+					bank_1k |= 0x80;
+					break;
+				case 2:
+					bank_1k &= 0x7F;
+					bank_1k |= 0x100;
+					break;
+				case 3:
+					bank_1k &= 0x7F;
+					bank_1k |= 0x180;
+					break;
+			}
+			addr = (bank_1k << 10) | (addr & 0x3FF);
+			return addr;
+		}
+
+		public override byte ReadPPU(int addr)
+		{
+			if (addr < 0x2000)
+			{
+				addr = MapCHR(addr);
+				if (VROM != null)
+					return VROM[addr + extra_vrom];
+				else return VRAM[addr];
+			}
+			else return base.ReadPPU(addr);
+		}
+
+		public override void NESSoftReset()
+		{
+			block = 0;
+			base.NESSoftReset();
+		}
+	}
+}