attempt to implement UNIF_UNL-SHERO - works except for Sachen title screen chr mapping

BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj

@@ -757,6 +757,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\UNIF\UNIF_UNL-CC-21.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\UNIF\UNIF_UNL-EDU2000.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\UNIF\UNIF_UNL-KOF97.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\UNIF\UNIF_UNL-SHERO.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\UNIF\UNIF_UNL-TF1201.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\UNIF\UNIF_UNL_DripGame.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\UxROM.cs">

BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/UNIF/UNIF_UNL-SHERO.cs

@@ -0,0 +1,87 @@
+using BizHawk.Common;
+
+namespace BizHawk.Emulation.Cores.Nintendo.NES
+{
+	public class UNIF_UNL_SHERO : MMC3Board_Base
+	{
+		[MapperProp]
+		public bool RegionAsia = false;
+
+		private byte reg;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "UNIF_UNL-SHERO":
+					break;
+				default:
+					return false;
+			}
+
+			BaseSetup();
+			AutoMapperProps.Apply(this);
+
+			return true;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			base.SyncState(ser);
+			ser.Sync("reg", ref reg);
+			ser.Sync("RegionAsia", ref RegionAsia);
+		}
+
+		public override void WriteEXP(int addr, byte value)
+		{
+			if (addr == 0x100)
+			{
+				reg = value;
+			}
+
+			base.WriteEXP(addr, value);
+		}
+
+		public override byte ReadEXP(int addr)
+		{
+			if (addr == 0x100)
+			{
+				return (byte)(RegionAsia ? 0xFF : 00);
+			}
+
+			return base.ReadEXP(addr);
+		}
+
+
+		public override byte ReadPPU(int addr)
+		{
+			// TODO: why doesn't this work?
+			if (addr < 0x2000 & ((reg & 0x40) > 0))
+			{
+				return VROM[addr];
+			}
+
+			return base.ReadPPU(addr);
+		}
+
+		protected override int Get_CHRBank_1K(int addr)
+		{
+			if (addr < 0x800)
+			{
+				return base.Get_CHRBank_1K(addr) | ((reg & 8) << 5);
+			}
+			else if (addr < 0x1000)
+			{
+				return base.Get_CHRBank_1K(addr) | ((reg & 4) << 6);
+			}
+			else if (addr < 0x1800)
+			{
+				return base.Get_CHRBank_1K(addr) | ((reg & 1) << 8);
+			}
+			else
+			{
+				return base.Get_CHRBank_1K(addr) | ((reg & 2) << 7);
+			}
+		}
+	}
+}