nes: implement NROM-368. doesn't implement any of the other variants like CNROM-368. supports both 48k and 64k modes

BizHawk.Emulation/BizHawk.Emulation.csproj

@@ -357,6 +357,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\NROM.cs">
       <SubType>Code</SubType>
     </Compile>
+    <Compile Include="Consoles\Nintendo\NES\Boards\NROM368.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\PxROM_FxROM.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\SachenSimple.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Sunsoft1.cs" />

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/NROM.cs

@@ -19,6 +19,10 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			switch (Cart.board_type)
 			{
 				case "MAPPER000":
+					if (Cart.prg_size <= 32)
+						break;
+					else
+						return false; // NROM-368
 				case "MAPPER219": //adelikat: a version of 3D-Block tries to use this ROM, but plays fine as NROM and 219 is undocumented by Disch
 					break;
 

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/NROM368.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Consoles.Nintendo
+{
+	public class NROM368 : NES.NESBoardBase
+	{
+		// not even one actual prototype of this pile of shit exists, and
+		// there are already two incompatible implementations.  pathetic.
+		bool small;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "UNIF_NROM-368": // ??
+					break;
+				case "MAPPER000":
+					if (Cart.prg_size == 48 || Cart.prg_size == 64)
+						break;
+					else
+						return false;
+				default:
+					return false;
+			}
+			AssertPrg(48, 64);
+			small = Cart.prg_size == 48;
+			SetMirrorType(Cart.pad_h, Cart.pad_v);
+			return true;
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			if (small)
+				return ROM[addr + 0x4000];
+			else
+				return ROM[addr];
+		}
+
+		public override byte ReadWRAM(int addr)
+		{
+			if (small)
+				return ROM[addr + 0x2000];
+			else
+				return ROM[addr + 0xa000];
+		}
+
+		public override byte ReadEXP(int addr)
+		{
+			if (addr < 0x800)
+				return NES.DB;
+			if (small)
+				return ROM[addr];
+			else
+				return ROM[addr + 0x8000];
+		}
+	}
+}