diff --git a/BizHawk.Emulation.Cores/CPUs/Z80A/Execute.cs b/BizHawk.Emulation.Cores/CPUs/Z80A/Execute.cs
index ce3fb3f729..089185c7ca 100644
--- a/BizHawk.Emulation.Cores/CPUs/Z80A/Execute.cs
+++ b/BizHawk.Emulation.Cores/CPUs/Z80A/Execute.cs
@@ -593,7 +593,7 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 					case 0x5C: INT_OP(NEG, A);							break; // NEG
 					case 0x5D: RETN_();									break; // RETI
 					case 0x5E: INT_MODE_(2);							break; // IM $0
-					case 0x5F: REG_OP_IR(TR, A, R);						break; // LD R, A
+					case 0x5F: REG_OP_IR(TR, A, R);						break; // LD A, R
 					case 0x60: IN_REG_(H, C);							break; // IN H, (C)
 					case 0x61: OUT_REG_(C, H);							break; // OUT (C), H
 					case 0x62: REG_OP_16_(SBC16, L, H, L, H);			break; // SBC HL, HL
diff --git a/BizHawk.Emulation.Cores/CPUs/Z80A/Operations.cs b/BizHawk.Emulation.Cores/CPUs/Z80A/Operations.cs
index 64ddc1ae5c..d80fb48022 100644
--- a/BizHawk.Emulation.Cores/CPUs/Z80A/Operations.cs
+++ b/BizHawk.Emulation.Cores/CPUs/Z80A/Operations.cs
@@ -12,17 +12,27 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 
 		public void I_Read_Func(ushort dest, ushort src_l, ushort src_h, ushort inc)
 		{
-			Regs[dest] = ReadMemory((ushort)((Regs[src_l] | (Regs[src_h]) << 8) + inc));
+			Regs[dest] = ReadMemory((ushort)((Regs[src_l] | (Regs[src_h] << 8)) + inc));
 		}
 
 		public void Write_Func(ushort dest_l, ushort dest_h, ushort src)
 		{
-			WriteMemory((ushort)(Regs[dest_l] | (Regs[dest_h]) << 8), (byte)Regs[src]);
+			WriteMemory((ushort)(Regs[dest_l] | (Regs[dest_h] << 8)), (byte)Regs[src]);
 		}
 
 		public void I_Write_Func(ushort dest_l, ushort dest_h, ushort inc,  ushort src)
 		{
-			WriteMemory((ushort)((Regs[dest_l] | (Regs[dest_h] + inc)) << 8), (byte)Regs[src]);
+			WriteMemory((ushort)((Regs[dest_l] | (Regs[dest_h] << 8)) + inc), (byte)Regs[src]);
+		}
+
+		public void OUT_Func(ushort dest, ushort src)
+		{
+			WriteHardware(Regs[dest], (byte)(Regs[src]));
+		}
+
+		public void IN_Func(ushort dest, ushort src)
+		{
+			Regs[dest] = ReadHardware(Regs[src]);
 		}
 
 		public void TR_Func(ushort dest, ushort src)
@@ -260,7 +270,7 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 
 		public void XOR8_Func(ushort dest, ushort src)
 		{
-			Regs[dest] = (ushort)(Regs[dest] ^ Regs[src]);
+			Regs[dest] = (ushort)((Regs[dest] ^ Regs[src]));
 
 			FlagZ = Regs[dest] == 0;
 			FlagC = false;
@@ -582,16 +592,6 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 			Regs[src_h] = temp;
 		}
 
-		public void OUT_Func(ushort dest, ushort src)
-		{
-			WriteHardware(Regs[dest], (byte)(Regs[src]));
-		}
-
-		public void IN_Func(ushort dest, ushort src)
-		{
-			Regs[dest] = ReadHardware(Regs[src]);
-		}
-
 		public void SBC_16_Func(ushort dest_l, ushort dest_h, ushort src_l, ushort src_h)
 		{
 			int Reg16_d = Regs[dest_l] | (Regs[dest_h] << 8);
diff --git a/BizHawk.Emulation.Cores/CPUs/Z80A/Z80A.cs b/BizHawk.Emulation.Cores/CPUs/Z80A/Z80A.cs
index 0f640eb124..dd982d720c 100644
--- a/BizHawk.Emulation.Cores/CPUs/Z80A/Z80A.cs
+++ b/BizHawk.Emulation.Cores/CPUs/Z80A/Z80A.cs
@@ -138,6 +138,7 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 		// Execute instructions
 		public void ExecuteOne()
 		{
+			if (Regs[A] > 255) { Console.WriteLine(RegPC); }
 			switch (cur_instr[instr_pntr++])
 			{
 				case IDLE:
@@ -172,7 +173,6 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 						iff1 = false;
 						NMI_();
 						NMICallback();
-
 					}
 					else if (iff1 && FlagI && NO_prefix)
 					{
@@ -213,6 +213,7 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 					}
 					instr_pntr = 0;
 					Regs[R]++;
+					Regs[R] &= 0xFF;
 					break;
 				case OP_R:
 					// determine if we repeat based on what operation we are doing
@@ -243,7 +244,6 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 					// if we don't repeat, continue on as a normal opcode fetch
 					if (repeat && temp3 > 0)
 					{
-						instr_pntr = 0;
 						cur_instr = new ushort[]
 									{IDLE,
 									DEC16, PCl, PCh,
@@ -278,7 +278,7 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 					{
 						// Interrupts can occur at this point, so process them accordingly
 						// Read the opcode of the next instruction				
-						if (EI_pending > 0)
+						if (EI_pending > 0 && NO_prefix)
 						{
 							EI_pending--;
 							if (EI_pending == 0)
@@ -343,10 +343,11 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 							if (OnExecFetch != null) OnExecFetch(RegPC);
 							if (TraceCallback != null) TraceCallback(State());
 							FetchInstruction(ReadMemory(RegPC++));
-							instr_pntr = 0;
 							Regs[R]++;
+							Regs[R] &= 0xFF;
 						}
 					}
+					instr_pntr = 0;
 					break;
 
 				case HALT:
@@ -378,7 +379,7 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 						iff1 = false;
 						NMI_();
 						NMICallback();
-
+						halted = false;
 					}
 					else if (iff1 && FlagI && NO_prefix)
 					{
@@ -410,11 +411,13 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 								break;
 						}
 						IRQCallback();
+						halted = false;
 					}
 					else
 					{
 						instr_pntr = 0;
 						Regs[R]++;
+						Regs[R] &= 0xFF;
 						cur_instr = new ushort[]
 						{IDLE,
 						IDLE,
@@ -538,7 +541,6 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 					break;
 				case DI:
 					IFF1 = IFF2 = false;
-					EI_pending = 0;
 					break;
 				case EXCH:
 					EXCH_16_Func(F_s, A_s, F, A);
@@ -561,6 +563,7 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 					if (prefix_src == IXCBpre) { IXCB_prefix = true; IXCB_prefetch = true; }
 					if (prefix_src == IYCBpre) { IYCB_prefix = true; IYCB_prefetch = true; }
 					Regs[R]++;
+					Regs[R] &= 0xFF;
 					break;
 				case ASGN:
 					ASGN_Func(cur_instr[instr_pntr++], cur_instr[instr_pntr++]);
@@ -577,7 +580,7 @@ namespace BizHawk.Emulation.Common.Components.Z80A
 					// Not currently implemented here
 					break;
 				case EI_RETN:
-					EI_pending = 1;
+					iff1 = iff2;
 					break;
 				case OUT:
 					OUT_Func(cur_instr[instr_pntr++], cur_instr[instr_pntr++]);