diff --git a/source/CPU/cpu65d02.h b/source/CPU/cpu65d02.h
index d9ea6595..60a239df 100644
--- a/source/CPU/cpu65d02.h
+++ b/source/CPU/cpu65d02.h
@@ -41,11 +41,23 @@ inline u8 DecClamp8( u8 x )
 // 1 B Exec
 // 2 G Read
 // 3 R Write
-// RGBA r= write, g = read, b = pc
-int g_aMemoryAccess[ 65536 ]; // TODO: Change to <stdint.h> int32_t
-u8 *g_pRead  = 0;
-u8 *g_pWrite = 0;
-u8 *g_pExec  = 0;
+// RGBA r = write, g = read, b = Program Counter
+const int HEATMAP_W_MASK = 0x00FF0000; // Red   Store
+const int HEATMAP_R_MASK = 0x0000FF00; // Green Load
+const int HEATMAP_X_MASK = 0x000000FF; // Blue  Exec
+
+
+// This is a memory heatmap
+// FF = accessed on this clock cycle
+// FE = accessed 1 clock cycles ago
+// FD = accessed 2 clock cycles ago
+// etc.
+// Displayed as 256x256 64K memory access
+int g_aMemoryHeatmap[ 65536 ]; // TODO: Change to <stdint.h> int32_t
+
+#define HEATMAP_W(addr) g_aMemoryHeatmap[ addr ] |= HEATMAP_W_MASK
+#define HEATMAP_R(addr) g_aMemoryHeatmap[ addr ] |= HEATMAP_R_MASK
+#define HEATMAP_X(addr) g_aMemoryHeatmap[ addr ] |= HEATMAP_X_MASK
 
 #undef READ
 #define READ ReadByte( addr, uExecutedCycles )
@@ -53,8 +65,7 @@ u8 *g_pExec  = 0;
 inline u8 ReadByte( u16 addr, int uExecutedCycles )
 {
     // TODO: We should have a single g_bDebuggerActive so we can have a single implementation across ][+ //e
-	(u8*) g_pRead = ((u8*)g_aMemoryAccess) + (addr * 4) + 3;
-	*g_pRead = IncClamp8( *g_pRead );
+	HEATMAP_R(addr);
 
 	return
 	( \
@@ -66,8 +77,7 @@ inline u8 ReadByte( u16 addr, int uExecutedCycles )
 
 #undef WRITE		 
 #define WRITE(a) \
-	(u8*) g_pWrite = ((u8*)g_aMemoryAccess) + (addr * 4) + 0; \
-	*g_pWrite = DecClamp8( *g_pWrite ); \
+	HEATMAP_W(addr);                                    \
 	{							    \
 	   memdirty[addr >> 8] = 0xFF;				    \
 	   LPBYTE page = memwrite[addr >> 8];		    \
@@ -112,6 +122,8 @@ static DWORD Cpu65D02 (DWORD uTotalCycles)
 		}
 		else
 
+        HEATMAP_X( regs.pc );
+
 		if (!Fetch(iOpcode, uExecutedCycles))
 			break;