NES - add mapper 61, chr mapping is off somehow

BizHawk.Emulation/BizHawk.Emulation.csproj

@@ -174,6 +174,7 @@
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper046.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper246.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper60.cs" />
+    <Compile Include="Consoles\Nintendo\NES\Boards\Mapper61.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\Mapper62.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\HKROM.cs" />
     <Compile Include="Consoles\Nintendo\NES\Boards\MMC3_family\Mapper012.cs" />

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/Mapper61.cs

@@ -0,0 +1,96 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BizHawk.Emulation.Consoles.Nintendo
+{
+	class Mapper61 : NES.NESBoardBase
+	{
+		/*
+		* Here are Disch's original notes:  
+		========================
+		=  Mapper 061          =
+		========================
+ 
+		Example Game:
+		--------------------------
+		20-in-1
+ 
+ 
+		Registers:
+		---------------------------
+ 
+		$8000-FFFF:  A~[.... .... M.LO HHHH]
+		H = High 4 bits of PRG Reg
+		L = Low bit of PRG Reg
+		O = PRG Mode
+		M = Mirroring (0=Vert, 1=Horz)
+ 
+ 
+		PRG Setup:
+		---------------------------
+ 
+		PRG Reg is 5 bits -- combination of 'H' and 'L' bits.
+ 
+					  $8000   $A000   $C000   $E000  
+					+-------------------------------+
+		PRG Mode 0: |            <$8000>            |
+					+-------------------------------+
+		PRG Mode 1: |     $8000     |     $8000     |
+					+---------------+---------------+
+		*/
+
+		public int prg_page;
+		public bool prg_mode;
+
+		public override bool Configure(NES.EDetectionOrigin origin)
+		{
+			switch (Cart.board_type)
+			{
+				case "MAPPER061":
+					break;
+				default:
+					return false;
+			}
+			SetMirrorType(EMirrorType.Vertical);
+			prg_page = 0;
+			prg_mode = false;
+			return true;
+		}
+
+		public override void SyncState(Serializer ser)
+		{
+			ser.Sync("prg_page", ref prg_page);
+			ser.Sync("prg_mode", ref prg_mode);
+			base.SyncState(ser);
+		}
+
+		public override void WritePRG(int addr, byte value)
+		{
+			if (addr.Bit(7))
+			{
+				SetMirrorType(EMirrorType.Horizontal);
+			}
+			else
+			{
+				SetMirrorType(EMirrorType.Vertical);
+			}
+
+			prg_mode = addr.Bit(4);
+			prg_page = ((addr & 0x0F) << 1) | ((addr & 0x20) >> 4);
+		}
+
+		public override byte ReadPRG(int addr)
+		{
+			if (prg_mode == false)
+			{
+				return ROM[((prg_page >> 1) * 0x8000) + addr];
+			}
+			else
+			{
+				return ROM[(prg_page * 0x4000) + (addr & 0x03FFF)];
+			}
+		}
+	}
+}