diff --git a/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj b/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
index 7734af1173..1ca6b88156 100644
--- a/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
+++ b/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
@@ -338,6 +338,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper250.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\MMC3.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\NES-QJ.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\RexSoftSL1632.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\TQROM.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\TLSROM.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\TVROM.cs" />
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/MMC3.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/MMC3.cs
index 12a15c7311..5d23863f4b 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/MMC3.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/MMC3.cs
@@ -12,7 +12,9 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 	{
 		//state
 		int reg_addr;
-		bool chr_mode, prg_mode;
+		public bool get_chr_mode { get { return chr_mode; } } // one of the pirate mappers needs this
+		bool chr_mode;
+		bool prg_mode;
 		public ByteBuffer regs = new ByteBuffer(8);
 
 		public byte mirror;
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/RexSoftSL1632.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/RexSoftSL1632.cs
new file mode 100644
index 0000000000..919f3555f6
--- /dev/null
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/RexSoftSL1632.cs
@@ -0,0 +1,139 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using BizHawk.Common;
+
+namespace BizHawk.Emulation.Cores.Nintendo.NES
+{
+	// p-p-p-p-pirate?
+	// http://svn.opennestopia.staulkor.com/Nestopia/core/board/NstBoardRexSoftSl1632.cpp
+	public class RexSoftSL1632 : MMC3Board_Base
+	{
+		// state
+		byte exmode;
+		int[] exprg = new int[4];
+		int[] exchr = new int[8];
+		byte exnmt;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "UNIF_UNL-SL1632":
+					break;
+				default:
+					return false;
+			}
+			BaseSetup();
+			exprg[3] = prg_mask;
+			exprg[2] = prg_mask - 1;
+			return true;
+		}
+
+		public override void SyncState(BizHawk.Common.Serializer ser)
+		{
+			base.SyncState(ser);
+			ser.Sync("exmode", ref exmode);
+			ser.Sync("exprg", ref exprg, false);
+			ser.Sync("exchr", ref exchr, false);
+			ser.Sync("exnmt", ref exnmt);
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			if (exmode.Bit(1))
+			{
+				return base.ReadPRG(addr);
+			}
+			else
+			{
+				int b = addr >> 13;
+				b = exprg[b];
+				b &= prg_mask;
+				return ROM[addr & 0x1fff | b << 13];
+			}
+		}
+
+		void SinkMirror()
+		{
+			SetMirrorType(exnmt.Bit(0) ? EMirrorType.Vertical : EMirrorType.Horizontal);
+		}
+
+		readonly static byte[] modes = { 5, 5, 3, 1 };
+		public override byte ReadPPU(int addr)
+		{
+			if (addr < 0x2000)
+			{
+				int bank;
+				if (exmode.Bit(1))
+				{
+					bank = Get_CHRBank_1K(addr);
+					int tmp = mmc3.get_chr_mode ? 2 : 0;
+					bank |= exmode << modes[addr >> 11 ^ tmp] & 0x100;
+				}
+				else
+				{
+					bank = exchr[addr >> 10];
+				}
+				bank &= chr_mask;
+				return VROM[addr & 0x3ff | bank << 10];
+			}
+			else
+			{
+				return base.ReadPPU(addr);
+			}
+		}
+
+
+		// this is stupid as hell
+		public override void WritePRG(int addr, byte value)
+		{
+			Console.WriteLine("{0:x4}:{1:x2}", addr, value);
+
+			if ((addr & 0x2131) == 0x2131)
+			{
+				exmode = value;
+				if (!exmode.Bit(1))
+				{
+					SinkMirror();
+				}
+			}
+
+			if (exmode.Bit(1))
+			{
+				switch (addr & 0x6001)
+				{
+					case 0x0000: base.WritePRG(0x0000, value); break;
+					case 0x0001: base.WritePRG(0x0001, value); break;
+					case 0x2000: SinkMirror(); break;
+					case 0x2001: base.WritePRG(0x2001, value); break;
+					case 0x4000: base.WritePRG(0x4000, value); break;
+					case 0x4001: base.WritePRG(0x4001, value); break;
+					case 0x6000: base.WritePRG(0x6000, value); break;
+					case 0x6001: base.WritePRG(0x6001, value); break;
+
+				}
+			}
+			else if (addr >= 3000 && addr <= 0x6003)
+			{
+				int offset = addr << 2 & 4;
+				addr = ((((addr & 0x2) | addr >> 10) >> 1) + 2) & 0x7;
+				exchr[addr] = (exchr[addr] & 0xf0 >> offset) | ((value & 0x0f) >> offset);
+				// sync chr
+			}
+			else
+			{
+				switch (addr & 0x7003)
+				{
+					case 0x0000: exprg[0] = value; break;
+					case 0x1000: exnmt = value; SinkMirror(); break;
+					case 0x2000: exprg[1] = value; break;
+				}
+			}
+		}
+
+
+
+	}
+}
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/SxROM.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/SxROM.cs
index 073353eb0c..d62b70753f 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/SxROM.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/SxROM.cs
@@ -532,6 +532,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 					Cart.vram_size = 8;
 					Cart.wram_size = 8;
 					Cart.wram_battery = true; // all SUROM boards had batteries
+					Console.WriteLine("Guessing SUROM for 512KiB PRG ROM");
 					break;
 				case "NES-SUROM": //dragon warrior 4
 				case "HVC-SUROM":