diff --git a/BizHawk.Emulation/BizHawk.Emulation.csproj b/BizHawk.Emulation/BizHawk.Emulation.csproj
index c6df43885f..beead85920 100644
--- a/BizHawk.Emulation/BizHawk.Emulation.csproj
+++ b/BizHawk.Emulation/BizHawk.Emulation.csproj
@@ -84,6 +84,7 @@
     <Compile Include="Computers\Commodore64\Cartridges\Mapper0000.cs" />
     <Compile Include="Computers\Commodore64\C64.Input.cs" />
     <Compile Include="Computers\Commodore64\Cartridges\Mapper0005.cs" />
+    <Compile Include="Computers\Commodore64\Cartridges\Mapper000F.cs" />
     <Compile Include="Computers\Commodore64\Cartridges\Mapper0012.cs" />
     <Compile Include="Computers\Commodore64\Cartridges\Mapper0013.cs" />
     <Compile Include="Computers\Commodore64\Cartridges\Mapper0020.cs" />
diff --git a/BizHawk.Emulation/Computers/Commodore64/Cartridges/Cartridge.cs b/BizHawk.Emulation/Computers/Commodore64/Cartridges/Cartridge.cs
index d9b70fef38..a5d3ce9f1b 100644
--- a/BizHawk.Emulation/Computers/Commodore64/Cartridges/Cartridge.cs
+++ b/BizHawk.Emulation/Computers/Commodore64/Cartridges/Cartridge.cs
@@ -70,6 +70,9 @@ namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
 						case 0x0005:
 							result = new Mapper0005(chipAddress, chipBank, chipData);
 							break;
+						case 0x000F:
+							result = new Mapper000F(chipAddress, chipBank, chipData);
+							break;
 						case 0x0012:
 							result = new Mapper0012(chipAddress, chipBank, chipData);
 							break;
diff --git a/BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper0005.cs b/BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper0005.cs
index e6079d6ed3..c2a48e2fd1 100644
--- a/BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper0005.cs
+++ b/BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper0005.cs
@@ -33,6 +33,7 @@ namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
 			}
 			else if (count == 32) //256k
 			{
+				// this specific config is a weird exception
 				pinGame = false;
 				pinExRom = false;
 				bankMask = 0x0F;
@@ -46,6 +47,13 @@ namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
 				bankMask = 0x0F;
 				banksA = new byte[16][];
 			}
+			else if (count == 8) //64k
+			{
+				pinGame = true;
+				pinExRom = false;
+				bankMask = 0x07;
+				banksA = new byte[8][];
+			}
 			else if (count == 4) //32k
 			{
 				pinGame = true;
@@ -53,6 +61,20 @@ namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
 				bankMask = 0x03;
 				banksA = new byte[4][];
 			}
+			else if (count == 2) //16k
+			{
+				pinGame = true;
+				pinExRom = false;
+				bankMask = 0x01;
+				banksA = new byte[2][];
+			}
+			else if (count == 1) //8k
+			{
+				pinGame = true;
+				pinExRom = false;
+				bankMask = 0x00;
+				banksA = new byte[1][];
+			}
 			else
 			{
 				// we don't know what format this is...
diff --git a/BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper000F.cs b/BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper000F.cs
new file mode 100644
index 0000000000..1349679c66
--- /dev/null
+++ b/BizHawk.Emulation/Computers/Commodore64/Cartridges/Mapper000F.cs
@@ -0,0 +1,123 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Computers.Commodore64.Cartridges
+{
+	// This is a mapper used commonly by System 3. It is
+	// also utilized by the short-lived C64 Game System.
+
+	// Bank select is DExx. You select them by writing to the
+	// register DE00+BankNr. For example, bank 01 is a write
+	// to DE01.
+
+	public class Mapper000F : Cartridge
+	{
+		private byte[][] banks = new byte[0][]; //8000
+		private uint bankMask;
+		private uint bankNumber;
+		private byte[] currentBank;
+		private byte[] dummyBank;
+
+		public Mapper000F(List<uint> newAddresses, List<uint> newBanks, List<byte[]> newData)
+		{
+			uint count = (uint)newAddresses.Count;
+
+			pinGame = true;
+			pinExRom = false;
+
+			// build dummy bank
+			dummyBank = new byte[0x2000];
+			for (uint i = 0; i < 0x2000; i++)
+				dummyBank[i] = 0xFF; // todo: determine if this is correct
+
+			if (count == 64) //512k
+			{
+				bankMask = 0x3F;
+				banks = new byte[64][];
+			}
+			else if (count == 32) //256k
+			{
+				bankMask = 0x1F;
+				banks = new byte[32][];
+			}
+			else if (count == 16) //128k
+			{
+				bankMask = 0x0F;
+				banks = new byte[16][];
+			}
+			else if (count == 8) //64k
+			{
+				bankMask = 0x07;
+				banks = new byte[8][];
+			}
+			else if (count == 4) //32k
+			{
+				bankMask = 0x03;
+				banks = new byte[4][];
+			}
+			else if (count == 2) //16k
+			{
+				bankMask = 0x01;
+				banks = new byte[2][];
+			}
+			else if (count == 1) //8k
+			{
+				bankMask = 0x00;
+				banks = new byte[1][];
+			}
+			else
+			{
+				// we don't know what format this is...
+				throw new Exception("This looks like a System 3/C64GS cartridge but cannot be loaded...");
+			}
+
+			// for safety, initialize all banks to dummy
+			for (uint i = 0; i < banks.Length; i++)
+				banks[i] = dummyBank;
+
+			// now load in the banks
+			for (int i = 0; i < count; i++)
+			{
+				if (newAddresses[i] == 0x8000)
+				{
+					banks[newBanks[i] & bankMask] = newData[i];
+				}
+			}
+
+			BankSet(0);
+		}
+
+		private void BankSet(uint index)
+		{
+			bankNumber = index & bankMask;
+			UpdateState();
+		}
+
+		public override byte Peek8000(int addr)
+		{
+			return currentBank[addr];
+		}
+
+		public override void PokeDE00(int addr, byte val)
+		{
+			BankSet((uint)addr);
+		}
+
+		public override byte Read8000(ushort addr)
+		{
+			return currentBank[addr];
+		}
+
+		private void UpdateState()
+		{
+			currentBank = banks[bankNumber];
+		}
+
+		public override void WriteDE00(ushort addr, byte val)
+		{
+			BankSet((uint)addr);
+		}
+	}
+}