diff --git a/BizHawk.Emulation.Cores/Calculator/TI83.cs b/BizHawk.Emulation.Cores/Calculator/TI83.cs
index a91bc2af6b..cbd23e1e28 100644
--- a/BizHawk.Emulation.Cores/Calculator/TI83.cs
+++ b/BizHawk.Emulation.Cores/Calculator/TI83.cs
@@ -1049,7 +1049,77 @@ namespace BizHawk.Emulation.Cores.Calculators
 
 		public void SetCpuRegister(string register, int value)
 		{
-			throw new NotImplementedException();
+			switch (register)
+			{
+				default:
+					throw new InvalidOperationException();
+				case "A":
+					cpu.RegisterA = (byte)value;
+					break;
+				case "AF":
+					cpu.RegisterAF = (byte)value;
+					break;
+				case "B":
+					cpu.RegisterB = (byte)value;
+					break;
+				case "BC":
+					cpu.RegisterBC = (byte)value;
+					break;
+				case "C":
+					cpu.RegisterC = (byte)value;
+					break;
+				case "D":
+					cpu.RegisterD = (byte)value;
+					break;
+				case "DE":
+					cpu.RegisterDE = (byte)value;
+					break;
+				case "E":
+					cpu.RegisterE = (byte)value;
+					break;
+				case "F":
+					cpu.RegisterF = (byte)value;
+					break;
+				case "H":
+					cpu.RegisterH = (byte)value;
+					break;
+				case "HL":
+					cpu.RegisterHL = (byte)value;
+					break;
+				case "I":
+					cpu.RegisterI = (byte)value;
+					break;
+				case "IX":
+					cpu.RegisterIX = (byte)value;
+					break;
+				case "IY":
+					cpu.RegisterIY = (byte)value;
+					break;
+				case "L":
+					cpu.RegisterL = (byte)value;
+					break;
+				case "PC":
+					cpu.RegisterPC = (ushort)value;
+					break;
+				case "R":
+					cpu.RegisterR = (byte)value;
+					break;
+				case "Shadow AF":
+					cpu.RegisterShadowAF = (byte)value;
+					break;
+				case "Shadow BC":
+					cpu.RegisterShadowBC = (byte)value;
+					break;
+				case "Shadow DE":
+					cpu.RegisterShadowDE = (byte)value;
+					break;
+				case "Shadow HL":
+					cpu.RegisterShadowHL = (byte)value;
+					break;
+				case "SP":
+					cpu.RegisterSP = (byte)value;
+					break;
+			}
 		}
 	}
 }
\ No newline at end of file
diff --git a/BizHawk.Emulation.Cores/Computers/Commodore64/C64.Core.cs b/BizHawk.Emulation.Cores/Computers/Commodore64/C64.Core.cs
index 666c92abe1..4aa03d21ae 100644
--- a/BizHawk.Emulation.Cores/Computers/Commodore64/C64.Core.cs
+++ b/BizHawk.Emulation.Cores/Computers/Commodore64/C64.Core.cs
@@ -123,7 +123,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64
 					board.cpu.S = (byte)value;
 					break;
 				case "PC":
-					board.cpu.PC = (byte)value;
+					board.cpu.PC = (ushort)value;
 					break;
 			}
 		}
diff --git a/BizHawk.Emulation.Cores/Computers/Commodore64/C64.cs b/BizHawk.Emulation.Cores/Computers/Commodore64/C64.cs
index 5521e72f69..e93ba91d49 100644
--- a/BizHawk.Emulation.Cores/Computers/Commodore64/C64.cs
+++ b/BizHawk.Emulation.Cores/Computers/Commodore64/C64.cs
@@ -141,7 +141,7 @@ namespace BizHawk.Emulation.Cores.Computers.Commodore64
 
 			//Console.WriteLine("CPUPC: " + C64Util.ToHex(board.cpu.PC, 4) + " 1541PC: " + C64Util.ToHex(disk.PC, 4));
 
-            int test = board.cpu.LagCycles;
+			int test = board.cpu.LagCycles;
 			CoreComm.DriveLED = DriveLED;
 		}
 
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.cs
index 0291938fc5..ea37d5104c 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Atari2600.cs
@@ -212,7 +212,7 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 					Cpu.S = (byte)value;
 					break;
 				case "PC":
-					Cpu.PC = (byte)value;
+					Cpu.PC = (ushort)value;
 					break;
 				case "Flag I":
 					Cpu.FlagI = value > 0;
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/7800/Atari7800.Core.cs b/BizHawk.Emulation.Cores/Consoles/Atari/7800/Atari7800.Core.cs
index 6f5aec8ed9..28a6c87e83 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/7800/Atari7800.Core.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/7800/Atari7800.Core.cs
@@ -49,7 +49,7 @@ namespace BizHawk.Emulation.Cores.Atari.Atari7800
 					theMachine.CPU.P = (byte)value;
 					break;
 				case "PC":
-					theMachine.CPU.PC = (byte)value;
+					theMachine.CPU.PC = (ushort)value;
 					break;
 				case "S":
 					theMachine.CPU.S = (byte)value;
diff --git a/BizHawk.Emulation.Cores/Consoles/Coleco/ColecoVision.cs b/BizHawk.Emulation.Cores/Consoles/Coleco/ColecoVision.cs
index 30e92e344e..4788fe9a17 100644
--- a/BizHawk.Emulation.Cores/Consoles/Coleco/ColecoVision.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Coleco/ColecoVision.cs
@@ -296,7 +296,77 @@ namespace BizHawk.Emulation.Cores.ColecoVision
 
 		public void SetCpuRegister(string register, int value)
 		{
-			throw new NotImplementedException();
+			switch (register)
+			{
+				default:
+					throw new InvalidOperationException();
+				case "A":
+					Cpu.RegisterA = (byte)value;
+					break;
+				case "AF":
+					Cpu.RegisterAF = (byte)value;
+					break;
+				case "B":
+					Cpu.RegisterB = (byte)value;
+					break;
+				case "BC":
+					Cpu.RegisterBC = (byte)value;
+					break;
+				case "C":
+					Cpu.RegisterC = (byte)value;
+					break;
+				case "D":
+					Cpu.RegisterD = (byte)value;
+					break;
+				case "DE":
+					Cpu.RegisterDE = (byte)value;
+					break;
+				case "E":
+					Cpu.RegisterE = (byte)value;
+					break;
+				case "F":
+					Cpu.RegisterF = (byte)value;
+					break;
+				case "H":
+					Cpu.RegisterH = (byte)value;
+					break;
+				case "HL":
+					Cpu.RegisterHL = (byte)value;
+					break;
+				case "I":
+					Cpu.RegisterI = (byte)value;
+					break;
+				case "IX":
+					Cpu.RegisterIX = (byte)value;
+					break;
+				case "IY":
+					Cpu.RegisterIY = (byte)value;
+					break;
+				case "L":
+					Cpu.RegisterL = (byte)value;
+					break;
+				case "PC":
+					Cpu.RegisterPC = (ushort)value;
+					break;
+				case "R":
+					Cpu.RegisterR = (byte)value;
+					break;
+				case "Shadow AF":
+					Cpu.RegisterShadowAF = (byte)value;
+					break;
+				case "Shadow BC":
+					Cpu.RegisterShadowBC = (byte)value;
+					break;
+				case "Shadow DE":
+					Cpu.RegisterShadowDE = (byte)value;
+					break;
+				case "Shadow HL":
+					Cpu.RegisterShadowHL = (byte)value;
+					break;
+				case "SP":
+					Cpu.RegisterSP = (byte)value;
+					break;
+			}
 		}
 	}
 }
\ No newline at end of file
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.cs
index f99a0a7c51..52246d92a8 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.cs
@@ -906,7 +906,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 					cpu.S = (byte)value;
 					break;
 				case "PC":
-					cpu.PC = (byte)value;
+					cpu.PC = (ushort)value;
 					break;
 				case "Flag I":
 					cpu.FlagI = value > 0;
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
index 2869c3e760..780832a7c2 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
@@ -512,7 +512,77 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 
 		public void SetCpuRegister(string register, int value)
 		{
-			throw new NotImplementedException();
+			switch (register)
+			{
+				default:
+					throw new InvalidOperationException();
+				case "A":
+					Cpu.RegisterA = (byte)value;
+					break;
+				case "AF":
+					Cpu.RegisterAF = (byte)value;
+					break;
+				case "B":
+					Cpu.RegisterB = (byte)value;
+					break;
+				case "BC":
+					Cpu.RegisterBC = (byte)value;
+					break;
+				case "C":
+					Cpu.RegisterC = (byte)value;
+					break;
+				case "D":
+					Cpu.RegisterD = (byte)value;
+					break;
+				case "DE":
+					Cpu.RegisterDE = (byte)value;
+					break;
+				case "E":
+					Cpu.RegisterE = (byte)value;
+					break;
+				case "F":
+					Cpu.RegisterF = (byte)value;
+					break;
+				case "H":
+					Cpu.RegisterH = (byte)value;
+					break;
+				case "HL":
+					Cpu.RegisterHL = (byte)value;
+					break;
+				case "I":
+					Cpu.RegisterI = (byte)value;
+					break;
+				case "IX":
+					Cpu.RegisterIX = (byte)value;
+					break;
+				case "IY":
+					Cpu.RegisterIY = (byte)value;
+					break;
+				case "L":
+					Cpu.RegisterL = (byte)value;
+					break;
+				case "PC":
+					Cpu.RegisterPC = (ushort)value;
+					break;
+				case "R":
+					Cpu.RegisterR = (byte)value;
+					break;
+				case "Shadow AF":
+					Cpu.RegisterShadowAF = (byte)value;
+					break;
+				case "Shadow BC":
+					Cpu.RegisterShadowBC = (byte)value;
+					break;
+				case "Shadow DE":
+					Cpu.RegisterShadowDE = (byte)value;
+					break;
+				case "Shadow HL":
+					Cpu.RegisterShadowHL = (byte)value;
+					break;
+				case "SP":
+					Cpu.RegisterSP = (byte)value;
+					break;
+			}
 		}
 
 		public void Dispose() { }