diff --git a/src/debugger/DiStella.cxx b/src/debugger/DiStella.cxx
index 3e559a972..bbed933ea 100644
--- a/src/debugger/DiStella.cxx
+++ b/src/debugger/DiStella.cxx
@@ -102,8 +102,25 @@ DiStella::DiStella(const CartDebug& dbg, CartDebug::DisassemblyList& list,
       myAddressQueue.pop();
       disasm(myPC, 1);
       if(myPCBeg <= myPCEnd)
+      {
+        // Tentatively mark all addresses in the range as CODE
+        // Note that this is a 'best-effort' approach, since
+        // Distella will normally keep going until the end of the
+        // range or branch is encountered
+        // However, addresses *specifically* marked as DATA/GFX/PGFX
+        // in the emulation core indicate that the CODE range has finished
+        // Therefore, we stop at the first such address encountered
         for (uInt32 k = myPCBeg; k <= myPCEnd; k++)
+        {
+          if(Debugger::debugger().getAddressDisasmType(k) &
+             (CartDebug::DATA|CartDebug::GFX|CartDebug::PGFX))
+          {
+            myPCEnd = k - 1;
+            break;
+          }
           mark(k, CartDebug::CODE);
+        }
+      }
 
       // When we get to this point, all addresses have been processed
       // starting from the initial one in the address list
diff --git a/src/emucore/M6502.ins b/src/emucore/M6502.ins
index c60e2ab39..41623269d 100644
--- a/src/emucore/M6502.ins
+++ b/src/emucore/M6502.ins
@@ -14,7 +14,7 @@
 // See the file "License.txt" for information on usage and redistribution of
 // this file, and for a DISCLAIMER OF ALL WARRANTIES.
 //
-// $Id: M6502.m4 2157 2010-10-21 21:01:00Z stephena $
+// $Id: M6502.m4 2158 2010-10-21 21:16:55Z stephena $
 //============================================================================
 
 /** 
@@ -24,7 +24,7 @@
     'm4 M6502.m4 > M6502.ins'
 
   @author  Bradford W. Mott
-  @version $Id: M6502.m4 2157 2010-10-21 21:01:00Z stephena $
+  @version $Id: M6502.m4 2158 2010-10-21 21:16:55Z stephena $
 */
 
 #ifndef NOTSAMEPAGE
@@ -916,10 +916,10 @@ case 0x90:
 {
   if(!C)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }
@@ -933,10 +933,10 @@ case 0xb0:
 {
   if(C)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }
@@ -950,10 +950,10 @@ case 0xf0:
 {
   if(!notZ)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }
@@ -993,10 +993,10 @@ case 0x30:
 {
   if(N)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }
@@ -1010,10 +1010,10 @@ case 0xD0:
 {
   if(notZ)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }
@@ -1027,10 +1027,10 @@ case 0x10:
 {
   if(!N)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }
@@ -1062,10 +1062,10 @@ case 0x50:
 {
   if(!V)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }
@@ -1079,10 +1079,10 @@ case 0x70:
 {
   if(V)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }
diff --git a/src/emucore/M6502.m4 b/src/emucore/M6502.m4
index 1de77dfff..9d05aefff 100644
--- a/src/emucore/M6502.m4
+++ b/src/emucore/M6502.m4
@@ -268,10 +268,10 @@ define(M6502_INDIRECTY_READMODIFYWRITE, `{
 define(M6502_BCC, `{
   if(!C)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }')
@@ -279,10 +279,10 @@ define(M6502_BCC, `{
 define(M6502_BCS, `{
   if(C)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }')
@@ -290,10 +290,10 @@ define(M6502_BCS, `{
 define(M6502_BEQ, `{
   if(!notZ)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }')
@@ -301,10 +301,10 @@ define(M6502_BEQ, `{
 define(M6502_BMI, `{
   if(N)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }')
@@ -312,10 +312,10 @@ define(M6502_BMI, `{
 define(M6502_BNE, `{
   if(notZ)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }')
@@ -323,10 +323,10 @@ define(M6502_BNE, `{
 define(M6502_BPL, `{
   if(!N)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }')
@@ -334,10 +334,10 @@ define(M6502_BPL, `{
 define(M6502_BVC, `{
   if(!V)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }')
@@ -345,10 +345,10 @@ define(M6502_BVC, `{
 define(M6502_BVS, `{
   if(V)
   {
-    peek(PC, DISASM_DATA);
+    peek(PC, DISASM_NONE);
     uInt16 address = PC + (Int8)operand;
     if(NOTSAMEPAGE(PC, address))
-      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_DATA);
+      peek((PC & 0xFF00) | (address & 0x00FF), DISASM_NONE);
     PC = address;
   }
 }')