fix 2600 Peek support, as best I can tell how.

BizHawk.Emulation/Consoles/Atari/2600/Atari2600.Core.cs

@@ -63,11 +63,28 @@ namespace BizHawk
 			addr = (ushort)(addr & 0x1FFF);
 			if ((addr & 0x1080) == 0)
 			{
-				return tia.ReadMemory(addr);
+				return tia.ReadMemory(addr, false);
 			}
 			else if ((addr & 0x1080) == 0x0080)
 			{
-				return m6532.ReadMemory(addr);
+				return m6532.ReadMemory(addr, false);
+			}
+			else
+			{
+				return rom[addr & 0x0FFF];
+			}
+		}
+
+		public byte BasePeekMemory(ushort addr)
+		{
+			addr = (ushort)(addr & 0x1FFF);
+			if ((addr & 0x1080) == 0)
+			{
+				return tia.ReadMemory(addr, true);
+			}
+			else if ((addr & 0x1080) == 0x0080)
+			{
+				return m6532.ReadMemory(addr, true);
 			}
 			else
 			{
@@ -106,8 +123,6 @@ namespace BizHawk
 
 		public byte PeekMemory(ushort addr)
 		{
-			//TODO - this is dangerous, because at least, the lag flag can get set by a read
-
 			byte temp = mapper.ReadMemory((ushort)(addr & 0x1FFF));
 
 			return temp;
@@ -217,7 +232,7 @@ namespace BizHawk
 			//if (render == false) return;
 		}
 
-		public byte ReadControls1()
+		public byte ReadControls1(bool peek)
 		{
 			if (CoreInputComm.InputCallback != null) CoreInputComm.InputCallback();
 			byte value = 0xFF;
@@ -227,11 +242,11 @@ namespace BizHawk
 			if (Controller["P1 Left"]) value &= 0xBF;
 			if (Controller["P1 Right"]) value &= 0x7F;
 			if (Controller["P1 Button"]) value &= 0xF7;
-			_islag = false;
+			if(!peek) _islag = false;
 			return value;
 		}
 
-		public byte ReadControls2()
+		public byte ReadControls2(bool peek)
 		{
 			if (CoreInputComm.InputCallback != null) CoreInputComm.InputCallback();
 			byte value = 0xFF;
@@ -241,7 +256,7 @@ namespace BizHawk
 			if (Controller["P2 Left"]) value &= 0xBF;
 			if (Controller["P2 Right"]) value &= 0x7F;
 			if (Controller["P2 Button"]) value &= 0xF7;
-			_islag = false;
+			if (!peek) _islag = false;
 			return value;
 		}
 
@@ -253,8 +268,9 @@ namespace BizHawk
 		public void SetP0Diff(bool setting) { p0difficulty = setting; }
 		public void SetP1Diff(bool setting) { p1difficulty = setting; }
 
-		public byte ReadConsoleSwitches()
+		public byte ReadConsoleSwitches(bool peek)
 		{
+			//TODO - zeromus isnt sure this should clear the lag flag
 			byte value = 0xFF;
 
 			bool select = Controller["Select"];
@@ -265,7 +281,7 @@ namespace BizHawk
 			if (bw) value &= 0xF7;
 			if (p0difficulty) value &= 0xBF;
 			if (p1difficulty) value &= 0x7F;
-			_islag = false;
+			if(!peek) _islag = false;
 			return value;
 		}
 	}
@@ -274,6 +290,7 @@ namespace BizHawk
 	{
 		public Atari2600 core;
 		public virtual byte ReadMemory(ushort addr) { return core.BaseReadMemory(addr); }
+		public virtual byte PeekMemory(ushort addr) { return core.BasePeekMemory(addr); }
 		public virtual void WriteMemory(ushort addr, byte value) { core.BaseWriteMemory(addr, value); }
 		public virtual void SyncState(Serializer ser) { }
 		public virtual void Dispose() { }

BizHawk.Emulation/Consoles/Atari/2600/M6532.cs

@@ -65,7 +65,7 @@ namespace BizHawk.Emulation.Consoles.Atari
 			timer.prescalerCount = 1 << timer.prescalerShift;
 		}
 
-		public byte ReadMemory(ushort addr)
+		public byte ReadMemory(ushort addr, bool peek)
 		{
 			// Register Select (?)
 			bool RS = (addr & 0x0200) != 0;
@@ -83,7 +83,7 @@ namespace BizHawk.Emulation.Consoles.Atari
 				{
 					// Read Output reg A
 					// Combine readings from player 1 and player 2
-					byte temp = (byte)(core.ReadControls1() & 0xF0 | ((core.ReadControls2() >> 4) & 0x0F));
+					byte temp = (byte)(core.ReadControls1(peek) & 0xF0 | ((core.ReadControls2(peek) >> 4) & 0x0F));
 					temp = (byte)(temp & ~ddra);
 					return temp;
 				}
@@ -95,7 +95,7 @@ namespace BizHawk.Emulation.Consoles.Atari
 				else if (registerAddr == 0x02)
 				{
 					// Read Output reg B
-					byte temp = core.ReadConsoleSwitches();
+					byte temp = core.ReadConsoleSwitches(peek);
 					temp = (byte)(temp & ~ddrb);
 					return temp;
 

BizHawk.Emulation/Consoles/Atari/2600/TIA.cs

@@ -999,8 +999,8 @@ namespace BizHawk.Emulation.Consoles.Atari
 				}
 			}
 		}
-
+		
-		public byte ReadMemory(ushort addr)
+		public byte ReadMemory(ushort addr, bool peek)
 		{
 			ushort maskedAddr = (ushort)(addr & 0x000F);
 			if (maskedAddr == 0x00) // CXM0P
@@ -1050,11 +1050,11 @@ namespace BizHawk.Emulation.Consoles.Atari
 			}
 			else if (maskedAddr == 0x0C) // INPT4
 			{
-				return (byte)((core.ReadControls1() & 0x08) != 0 ? 0x80 : 0x00);
+				return (byte)((core.ReadControls1(peek) & 0x08) != 0 ? 0x80 : 0x00);
 			}
 			else if (maskedAddr == 0x0D) // INPT5
 			{
-				return (byte)((core.ReadControls2() & 0x08) != 0 ? 0x80 : 0x00);
+				return (byte)((core.ReadControls2(peek) & 0x08) != 0 ? 0x80 : 0x00);
 			}
 
 			return 0x00;

BizHawk.Emulation/Consoles/Atari/2600/oldTIA.cs

@@ -352,7 +352,7 @@ namespace BizHawk.Emulation.Consoles.Atari
 			}
 		}
 
-		public byte ReadMemory(ushort addr)
+		public byte ReadMemory(ushort addr, bool peek)
 		{
 			ushort maskedAddr = (ushort)(addr & 0x000F);
 			Console.WriteLine("TIA read:  " + maskedAddr.ToString("x"));
@@ -370,12 +370,12 @@ namespace BizHawk.Emulation.Consoles.Atari
 				{
 					if (inpt4 == true)
 					{
-						inpt4 = ((core.ReadControls1() & 0x08) != 0);
+						inpt4 = ((core.ReadControls1(peek) & 0x08) != 0);
 					}
 				}
 				else
 				{
-					inpt4 = ((core.ReadControls1() & 0x08) != 0);
+					inpt4 = ((core.ReadControls1(peek) & 0x08) != 0);
 				}
 				return (byte)(inpt4 ? 0x80 : 0x00);