diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.Core.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.Core.cs
index 1699e2d2ec..ee1267a5fd 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.Core.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.Core.cs
@@ -60,18 +60,15 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 		// keeps track of tia cycles, 3 cycles per CPU cycle
 		private int cyc_counter;
 
-		private static MapperBase SetMultiCartMapper(int romLength, int gameTotal)
+		private MapperBase SetMultiCartMapper(int romLength, int gameTotal)
 		{
-			switch (romLength / gameTotal)
+			return (romLength / gameTotal) switch
 			{
-				case 1024 * 2: // 2K
-					return new Multicart2K(gameTotal);
-				default:
-				case 1024 * 4: // 4K
-					return new Multicart4K(gameTotal);
-				case 1024 * 8: // 8K
-					return new Multicart8K(gameTotal);
-			}
+				1024 * 2 => new Multicart2K(this, gameTotal),
+				1024 * 4 => new Multicart4K(this, gameTotal),
+				1024 * 8 => new Multicart8K(this, gameTotal),
+				_ => new Multicart4K(this, gameTotal)
+			};
 		}
 
 		internal byte BaseReadMemory(ushort addr)
@@ -199,123 +196,47 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 		private void RebootCore()
 		{
 			// Regenerate mapper here to make sure its state is entirely clean
-			switch (_game.GetOptionsDict()["m"])
+			_mapper = _game.GetOptionsDict()["m"] switch
 			{
-				case "2IN1":
-					_mapper = SetMultiCartMapper(Rom.Length, 2);
-					break;
-				case "4IN1":
-					_mapper = SetMultiCartMapper(Rom.Length, 4);
-					break;
-				case "8IN1":
-					_mapper = SetMultiCartMapper(Rom.Length, 8);
-					break;
-				case "16IN1":
-					_mapper = SetMultiCartMapper(Rom.Length, 16);
-					break;
-				case "32IN1":
-					_mapper = SetMultiCartMapper(Rom.Length, 32);
-					break;
-				case "AR":
-					_mapper = new mAR(this); // This mapper has to set up configurations in the contructor.
-					break;
-				case "4K":
-					_mapper = new m4K();
-					break;
-				case "2K":
-					_mapper = new m2K();
-					break;
-				case "CM":
-					_mapper = new mCM();
-					break;
-				case "CV":
-					_mapper = new mCV();
-					break;
-				case "DPC":
-					_mapper = new mDPC();
-					break;
-				case "DPC+":
-					_mapper = new mDPCPlus();
-					break;
-				case "F8":
-					_mapper = new mF8();
-					break;
-				case "F8SC":
-					_mapper = new mF8SC();
-					break;
-				case "F6":
-					_mapper = new mF6();
-					break;
-				case "F6SC":
-					_mapper = new mF6SC();
-					break;
-				case "F4":
-					_mapper = new mF4();
-					break;
-				case "F4SC":
-					_mapper = new mF4SC();
-					break;
-				case "FE":
-					_mapper = new mFE();
-					break;
-				case "E0":
-					_mapper = new mE0();
-					break;
-				case "3F":
-					_mapper = new m3F();
-					break;
-				case "FA":
-					_mapper = new mFA();
-					break;
-				case "FA2":
-					_mapper = new mFA2();
-					break;
-				case "E7":
-					_mapper = new mE7();
-					break;
-				case "F0":
-					_mapper = new mF0();
-					break;
-				case "UA":
-					_mapper = new mUA();
-					break;
-
-				// Special Sega Mapper which has swapped banks
-				case "F8_sega":
-					_mapper = new mF8_sega();
-					break;
+				"2IN1" => SetMultiCartMapper(Rom.Length, 2),
+				"4IN1" => SetMultiCartMapper(Rom.Length, 4),
+				"8IN1" => SetMultiCartMapper(Rom.Length, 8),
+				"16IN1" => SetMultiCartMapper(Rom.Length, 16),
+				"32IN1" => SetMultiCartMapper(Rom.Length, 32),
+				"AR" => new mAR(this),
+				"4K" => new m4K(this),
+				"2K" => new m2K(this),
+				"CM" => new mCM(this),
+				"CV" => new mCV(this),
+				"DPC" => new mDPC(this),
+				"DPC+" => new mDPCPlus(this),
+				"F8" => new mF8(this),
+				"F8SC" => new mF8SC(this),
+				"F6" => new mF6(this),
+				"F6SC" => new mF6SC(this),
+				"F4" => new mF4(this),
+				"F4SC" => new mF4SC(this),
+				"FE" => new mFE(this),
+				"E0" => new mE0(this),
+				"3F" => new m3F(this),
+				"FA" => new mFA(this),
+				"FA2" => new mFA2(this),
+				"E7" => new mE7(this),
+				"F0" => new mF0(this),
+				"UA" => new mUA(this),
+				"F8_sega" => new mF8_sega(this),
 
 				// Homebrew mappers
-				case "3E":
-					_mapper = new m3E();
-					break;
-				case "0840":
-					_mapper = new m0840();
-					break;
-				case "MC":
-					_mapper = new mMC();
-					break;
-				case "EF":
-					_mapper = new mEF();
-					break;
-				case "EFSC":
-					_mapper = new mEFSC();
-					break;
-				case "X07":
-					_mapper = new mX07();
-					break;
-				case "4A50":
-					_mapper = new m4A50();
-					break;
-				case "SB":
-					_mapper = new mSB();
-					break;
-
-				default:
-					throw new InvalidOperationException("mapper not supported: " + _game.GetOptionsDict()["m"]);
-			}
-
-			_mapper.Core = this;
+				"3E" => new m3E(this),
+				"0840" => new m0840(this),
+				"MC" => new mMC(this),
+				"EF" => new mEF(this),
+				"EFSC" => new mEFSC(this),
+				"X07" => new mX07(this),
+				"4A50" => new m4A50(this),
+				"SB" => new mSB(this),
+				_ => throw new InvalidOperationException("mapper not supported: " + _game.GetOptionsDict()["m"])
+			};
 
 			_lagCount = 0;
 			Cpu = new MOS6502X<CpuLink>(new CpuLink(this));
@@ -342,7 +263,6 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 			HardReset();
 
-			// Show mapper class on romstatusdetails
 			RomDetails = $"{_game.Name}\r\nSHA1:{Rom.HashSHA1()}\r\nMD5:{Rom.HashMD5()}\r\nMapper Impl \"{_mapper.GetType()}\"";
 
 			// Some games (ex. 3D tic tac toe), turn off the screen for extended periods, so we need to allow for this here.
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/MapperBase.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/MapperBase.cs
index ab0116ae2e..a91421c1a8 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/MapperBase.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/MapperBase.cs
@@ -4,29 +4,26 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 {
 	public class MapperBase
 	{
-		public Atari2600 Core { get; set; }
+		public MapperBase(Atari2600 core)
+		{
+			Core = core;
+		}
+
+		protected readonly Atari2600 Core;
 
 		public virtual byte[] CartRam => new byte[0];
 
 		public virtual byte ReadMemory(ushort addr)
-		{
-			return Core.BaseReadMemory(addr);
-		}
+			=> Core.BaseReadMemory(addr);
 
 		public virtual byte PeekMemory(ushort addr)
-		{
-			return Core.BasePeekMemory(addr);
-		}
+			=> Core.BasePeekMemory(addr);
 
 		public virtual void WriteMemory(ushort addr, byte value)
-		{
-			Core.BaseWriteMemory(addr, value);
-		}
+			=> Core.BaseWriteMemory(addr, value);
 
 		public virtual void PokeMemory(ushort addr, byte value)
-		{
-			Core.BasePokeMemory(addr, value);
-		}
+			=> Core.BasePokeMemory(addr, value);
 
 		public virtual void SyncState(Serializer ser)
 		{
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart2K.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart2K.cs
index f98905f8d4..ade1261eba 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart2K.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart2K.cs
@@ -10,7 +10,8 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 		private int _gameTotal;
 		private int _currentGame;
 
-		public Multicart2K(int gameTotal)
+		public Multicart2K(Atari2600 core, int gameTotal)
+			: base(core)
 		{
 			_gameTotal = gameTotal;
 			_currentGame = 0;
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart4K.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart4K.cs
index 2ae332d828..e28ed8153e 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart4K.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart4K.cs
@@ -10,7 +10,8 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 		private int _gameTotal;
 		private int _currentGame;
 
-		public Multicart4K(int gameTotal)
+		public Multicart4K(Atari2600 core, int gameTotal)
+			: base(core)
 		{
 			_gameTotal = gameTotal;
 			_currentGame = 0;
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart8K.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart8K.cs
index b7aac4dc1e..fd2612e641 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart8K.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/Multicart8K.cs
@@ -12,7 +12,8 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 		private int _gameTotal;
 		private int _currentGame;
 
-		public Multicart8K(int gameTotal)
+		public Multicart8K(Atari2600 core, int gameTotal)
+			: base(core)
 		{
 			_gameTotal = gameTotal;
 			_currentGame = 0;
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m0840.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m0840.cs
index e6ae90984d..ab36f1637d 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m0840.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m0840.cs
@@ -23,6 +23,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	*/
 	internal class m0840 : MapperBase 
 	{
+		public m0840(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _bank4K;
 
 		public override void SyncState(Serializer ser)
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m2K.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m2K.cs
index 94dfc502a0..701f8a595b 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m2K.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m2K.cs
@@ -2,6 +2,10 @@
 {
 	internal class m2K : MapperBase
 	{
+		public m2K(Atari2600 core) : base(core)
+		{
+		}
+
 		public override byte ReadMemory(ushort addr)
 		{
 			if (addr < 0x1000)
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3E.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3E.cs
index 14d73498cc..4ef09e19c3 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3E.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3E.cs
@@ -22,6 +22,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	*/
 	internal class m3E : MapperBase
 	{
+		public m3E(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _lowbank2K;
 		private int _rambank1K;
 		private bool _hasRam;
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3F.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3F.cs
index bc23b12875..5f2bf09f8a 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3F.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3F.cs
@@ -23,6 +23,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 	internal class m3F : MapperBase 
 	{
+		public m3F(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _lowbank2K;
 
 		public override void SyncState(Serializer ser)
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m4A50.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m4A50.cs
index 115ece1869..dd727e07a2 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m4A50.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m4A50.cs
@@ -43,6 +43,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 	internal class m4A50 : MapperBase 
 	{
+		public m4A50(Atari2600 core) : base(core)
+		{
+		}
+
 		private byte[] _ram = new byte[32768];
 
 		private byte _lastData = 0xFF;
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m4K.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m4K.cs
index 44f9bef985..feba337201 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m4K.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m4K.cs
@@ -2,6 +2,10 @@
 {
 	internal class m4K : MapperBase
 	{
+		public m4K(Atari2600 core) : base(core)
+		{
+		}
+
 		public override byte ReadMemory(ushort addr)
 		{
 			if (addr < 0x1000)
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mAR.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mAR.cs
index 15b46362b9..fa0e034daa 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mAR.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mAR.cs
@@ -33,9 +33,8 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 {
 	internal class mAR : MapperBase
 	{
-		public mAR(Atari2600 core)
+		public mAR(Atari2600 core) : base(core)
 		{
-			Core = core;
 			InitializeSettings();
 		}
 
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mCM.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mCM.cs
index 8b576f71b9..86b781337a 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mCM.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mCM.cs
@@ -179,6 +179,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	*/
 	internal class mCM : MapperBase
 	{
+		public mCM(Atari2600 core) : base(core)
+		{
+		}
+
 		// TODO: PokeMem
 		private byte[] _ram = new byte[2048];
 		private int _bank4K = 3; // On Start up, controller port is all 1's, so start on the last bank, flags enabled
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mCV.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mCV.cs
index 35b7d1a992..5947f62757 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mCV.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mCV.cs
@@ -17,6 +17,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	 */
 	internal class mCV : MapperBase
 	{
+		public mCV(Atari2600 core) : base(core)
+		{
+		}
+
 		private byte[] _ram = new byte[1024];
 
 		public override byte[] CartRam => _ram;
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mDPC.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mDPC.cs
index 89ed8c7749..1fb081a310 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mDPC.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mDPC.cs
@@ -225,6 +225,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	 */
 	internal class mDPC : MapperBase
 	{
+		public mDPC(Atari2600 core) : base(core)
+		{
+		}
+
 		// Table for computing the input bit of the random number generator's
 		// shift register (it's the NOT of the EOR of four bits)
 		private readonly byte[] _randomInputBits = { 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1 };
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mDPCPlus.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mDPCPlus.cs
index 40537e32e1..f8962c29a8 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mDPCPlus.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mDPCPlus.cs
@@ -12,7 +12,7 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	internal class mDPCPlus : MapperBase
 	{
 		// TODO: PokeMem, and everything else
-		public mDPCPlus()
+		public mDPCPlus(Atari2600 core) : base(core)
 		{
 			throw new NotImplementedException();
 		}
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mE0.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mE0.cs
index 3e79c1bedb..04a0941117 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mE0.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mE0.cs
@@ -25,6 +25,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 	internal class mE0 : MapperBase 
 	{
+		public mE0(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _toggle1;
 		private int _toggle2;
 		private int _toggle3;
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mE7.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mE7.cs
index 2f4e251d4d..cfac7bd5dc 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mE7.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mE7.cs
@@ -36,6 +36,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 		private bool _enableRam0;
 
+		public mE7(Atari2600 core) : base(core)
+		{
+		}
+
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mEF.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mEF.cs
index 8edd72cf65..b32c627cb4 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mEF.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mEF.cs
@@ -16,6 +16,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	{
 		private int _toggle;
 
+		public mEF(Atari2600 core) : base(core)
+		{
+		}
+
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mEFSC.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mEFSC.cs
index 03784243db..fe56954157 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mEFSC.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mEFSC.cs
@@ -9,6 +9,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	*/
 	internal class mEFSC : MapperBase
 	{
+		public mEFSC(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _bank4k;
 		private byte[] _ram = new byte[128];
 
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF0.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF0.cs
index a46bb897be..c1e6328f84 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF0.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF0.cs
@@ -22,6 +22,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	{
 		private int _bank;
 
+		public mF0(Atari2600 core) : base(core)
+		{
+		}
+
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF4.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF4.cs
index 22d395cf16..56a48af6a4 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF4.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF4.cs
@@ -14,6 +14,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	{
 		private int _toggle;
 
+		public mF4(Atari2600 core) : base(core)
+		{
+		}
+
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF4SC.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF4SC.cs
index d557160f48..38506d9312 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF4SC.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF4SC.cs
@@ -11,6 +11,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 		private int _bank4k;
 		private byte[] _ram = new byte[128];
 
+		public mF4SC(Atari2600 core) : base(core)
+		{
+		}
+
 		public override byte[] CartRam => _ram;
 
 		public override void SyncState(Serializer ser)
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF6.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF6.cs
index 4206b25ca5..0ca2abd16e 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF6.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF6.cs
@@ -13,6 +13,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 	internal class mF6 : MapperBase 
 	{
+		public mF6(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _toggle;
 
 		public override void SyncState(Serializer ser)
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF6SC.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF6SC.cs
index a9020458a0..8d1283634c 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF6SC.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF6SC.cs
@@ -8,6 +8,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	*/
 	internal class mF6SC : MapperBase
 	{
+		public mF6SC(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _bank4k;
 		private byte[] _ram = new byte[128];
 
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8.cs
index 45643c6650..006b8e7ce6 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8.cs
@@ -23,6 +23,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	{
 		private int _bank4K;
 
+		public mF8(Atari2600 core) : base(core)
+		{
+		}
+
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8SC.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8SC.cs
index e7c97daa9d..0054ce4464 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8SC.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8SC.cs
@@ -8,6 +8,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	*/
 	internal class mF8SC : MapperBase
 	{
+		public mF8SC(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _bank_4K;
 		private byte[] _ram = new byte[128];
 
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8_sega.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8_sega.cs
index 50dc0c866b..1707ad3dea 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8_sega.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mF8_sega.cs
@@ -13,6 +13,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	{
 		private int _bank4K = 1;
 
+		public mF8_sega(Atari2600 core) : base(core)
+		{
+		}
+
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFA.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFA.cs
index 8c4563a86a..52b76f4dfa 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFA.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFA.cs
@@ -19,6 +19,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 		private int _toggle;
 		private byte[] _ram = new byte[256];
 
+		public mFA(Atari2600 core) : base(core)
+		{
+		}
+
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFA2.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFA2.cs
index 7e33f5f07b..b6e7c713ea 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFA2.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFA2.cs
@@ -10,6 +10,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	*/
 	internal class mFA2 : MapperBase
 	{
+		public mFA2(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _bank4k;
 		private byte[] _ram = new  byte[256];
 
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFE.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFE.cs
index cca8c8983d..2889b2de74 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFE.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mFE.cs
@@ -56,6 +56,10 @@
 	*/
 	internal class mFE : MapperBase 
 	{
+		public mFE(Atari2600 core) : base(core)
+		{
+		}
+
 		public override byte ReadMemory(ushort addr)
 		{
 			if (addr < 0x1000)
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mMC.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mMC.cs
index 0ca8918345..4236f549a3 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mMC.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mMC.cs
@@ -61,7 +61,7 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 	internal class mMC : MapperBase 
 	{
-		public mMC()
+		public mMC(Atari2600 core) : base(core)
 		{
 			throw new NotImplementedException();
 		}
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mSB.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mSB.cs
index f978fb10b6..3ef4b4277a 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mSB.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mSB.cs
@@ -11,6 +11,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 		private int _bank4K;
 		private int myStartBank => (Core.Rom.Length >> 12) - 1;
 
+		public mSB(Atari2600 core) : base(core)
+		{
+		}
+
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mUA.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mUA.cs
index 75e9c372ea..e392bbc2d1 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mUA.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mUA.cs
@@ -14,6 +14,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 	internal class mUA : MapperBase 
 	{
+		public mUA(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _toggle;
 
 		public override void SyncState(Serializer ser)
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mX07.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mX07.cs
index 895a8082e9..7fc4c2f039 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mX07.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mX07.cs
@@ -35,6 +35,10 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 	internal class mX07 : MapperBase
 	{
+		public mX07(Atari2600 core) : base(core)
+		{
+		}
+
 		private int _rombank2K;
 
 		public override void SyncState(Serializer ser)