diff --git a/BizHawk.Emulation/Consoles/Atari/2600/Mappers/mE7.cs b/BizHawk.Emulation/Consoles/Atari/2600/Mappers/mE7.cs
index bea152eea8..7b38fe5a2b 100644
--- a/BizHawk.Emulation/Consoles/Atari/2600/Mappers/mE7.cs
+++ b/BizHawk.Emulation/Consoles/Atari/2600/Mappers/mE7.cs
@@ -5,8 +5,118 @@ using System.Text;
 
 namespace BizHawk.Emulation.Consoles.Atari._2600
 {
+	/*
+	E7 (M-Network)
+	-----
+
+	M-network wanted something of their own too, so they came up with what they called 
+	"Big Game" (this was printed on the prototype ASICs on the prototype carts).  It
+	can handle up to 16K of ROM and 2K of RAM.
+
+	1000-17FF is selectable
+	1800-19FF is RAM
+	1A00-1FFF is fixed to the last 1.5K of ROM
+
+	Accessing 1FE0 through 1FE6 selects bank 0 through bank 6 of the ROM into 1000-17FF.
+	Accessing 1FE7 enables 1K of the 2K RAM, instead.
+
+	When the RAM is enabled, this 1K appears at 1000-17FF.  1000-13FF is the write port, 1400-17FF
+	is the read port.  
+
+	1800-19FF also holds RAM. 1800-18FF is the write port, 1900-19FF is the read port.  
+	Only 256 bytes of RAM is accessable at time, but there are four different 256 byte
+	banks making a total of 1K accessable here.
+
+	Accessing 1FE8 through 1FEB select which 256 byte bank shows up.
+	*/
+
 	class mE7 : MapperBase
 	{
+		int toggle = 0;
+		int rambank1_toggle = 0;
+		ByteBuffer rambank0 = new ByteBuffer(1024);
+		ByteBuffer rambank1 = new ByteBuffer(1024);
+		bool EnableRam0 = false;
 
+		public override byte ReadMemory(ushort addr)
+		{
+			Address(addr);
+			if (addr < 0x1000) return base.ReadMemory(addr);
+			else if (addr < 0x1400)
+			{
+				if (EnableRam0)
+				{
+					return rambank0[(addr & 1023)];
+				}
+				else
+				{
+					return core.rom[toggle * 2 * 1024 + (addr & 0x7FF)];
+				}
+			}
+			else if (addr < 0x1800) return core.rom[toggle * 2 * 1024 + (addr & 0x7FF)];
+			else if (addr < 0x1A00) return rambank1[toggle * 256 + (addr & 0x255)];
+			else if (addr < 0x2000) return core.rom[14848 + (addr & 0x5FF)]; //Fixed to last 1.5K
+			else return base.ReadMemory(addr);
+		}
+		public override void WriteMemory(ushort addr, byte value)
+		{
+			Address(addr);
+			if (addr < 0x1000) base.WriteMemory(addr, value);
+			else if (addr < 0x1400) rambank0[addr & 0x3FF] = value;
+			else if (addr >= 0x1800 && addr < 0x2000) rambank0[(addr & 0xFF) + (rambank1_toggle * 0x100)] = value;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			base.SyncState(ser);
+			ser.Sync("toggle", ref toggle);
+			ser.Sync("rambank0", ref rambank0);
+			ser.Sync("rambank1", ref rambank1);
+			ser.Sync("EnableRam0", ref EnableRam0);
+			ser.Sync("rambank1_toggle", ref rambank1_toggle);
+		}
+
+		void Address(ushort addr)
+		{
+			switch (addr)
+			{
+				case 0x1FE0:
+					toggle = 0;
+					break;
+				case 0x1FE1:
+					toggle = 1;
+					break;
+				case 0x1FE2:
+					toggle = 2;
+					break;
+				case 0x1FE3:
+					toggle = 3;
+					break;
+				case 0x1FE4:
+					toggle = 4;
+					break;
+				case 0x1FE5:
+					toggle = 5;
+					break;
+				case 0x1FE6:
+					toggle = 6;
+					break;
+				case 0x1FE7:
+					EnableRam0 = true;
+					break;
+				case 0x1FE8:
+					rambank1_toggle = 0;
+					break;
+				case 0x1FE9:
+					rambank1_toggle = 1;
+					break;
+				case 0x1FEA:
+					rambank1_toggle = 2;
+					break;
+				case 0x1FEB:
+					rambank1_toggle = 3;
+					break;
+			}
+		}
 	}
 }