diff --git a/src/debugger/CartDebug.cxx b/src/debugger/CartDebug.cxx
index b1111c057..1a01fbc43 100644
--- a/src/debugger/CartDebug.cxx
+++ b/src/debugger/CartDebug.cxx
@@ -30,11 +30,13 @@
 #include "Settings.hxx"
 #include "Version.hxx"
 #include "CartDebug.hxx"
+#include "CartDebugWidget.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 CartDebug::CartDebug(Debugger& dbg, Console& console, const OSystem& osystem)
   : DebuggerSystem(dbg, console),
     myOSystem(osystem),
+    myDebugWidget(0),
     myRWPortAddress(0),
     myLabelLength(8)   // longest pre-defined label
 {
@@ -147,6 +149,9 @@ void CartDebug::saveOldState()
   myOldState.ram.clear();
   for(uInt32 i = 0; i < myOldState.rport.size(); ++i)
     myOldState.ram.push_back(peek(myOldState.rport[i]));
+
+  if(myDebugWidget)
+    myDebugWidget->saveOldState();
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/debugger/CartDebug.hxx b/src/debugger/CartDebug.hxx
index 7bb0a9a2e..c6c71b92d 100644
--- a/src/debugger/CartDebug.hxx
+++ b/src/debugger/CartDebug.hxx
@@ -21,6 +21,7 @@
 #define CART_DEBUG_HXX
 
 class Settings;
+class CartDebugWidget;
 
 #include <map>
 #include <set>
@@ -97,6 +98,11 @@ class CartDebug : public DebuggerSystem
     void saveOldState();
     string toString();
 
+    // Used to get/set the debug widget, which contains cart-specific
+    // functionality
+    CartDebugWidget* getDebugWidget() const { return myDebugWidget; }
+    void setDebugWidget(CartDebugWidget* w) { myDebugWidget = w; }
+
     // The following assume that the given addresses are using the
     // correct read/write port ranges; no checking will be done to
     // confirm this.
@@ -321,6 +327,8 @@ class CartDebug : public DebuggerSystem
     CartState myState;
     CartState myOldState;
 
+    CartDebugWidget* myDebugWidget;
+
     // A complete record of relevant diassembly information for each bank
     Common::Array<BankInfo> myBankInfo;
 
diff --git a/src/debugger/Debugger.cxx b/src/debugger/Debugger.cxx
index 4ecbb4537..e5a18e865 100644
--- a/src/debugger/Debugger.cxx
+++ b/src/debugger/Debugger.cxx
@@ -40,6 +40,7 @@
 #include "TIA.hxx"
 
 #include "CartDebug.hxx"
+#include "CartDebugWidget.hxx"
 #include "CpuDebug.hxx"
 #include "RiotDebug.hxx"
 #include "TIADebug.hxx"
@@ -181,6 +182,7 @@ void Debugger::initialize()
   myBaseDialog = myDialog;
 
   myRewindManager = new RewindManager(*myOSystem, myDialog->rewindButton());
+  myCartDebug->setDebugWidget(&(myDialog->cartDebug()));
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
diff --git a/src/debugger/Debugger.hxx b/src/debugger/Debugger.hxx
index 4ad16e8af..54b1dcb5e 100644
--- a/src/debugger/Debugger.hxx
+++ b/src/debugger/Debugger.hxx
@@ -75,7 +75,6 @@ class Debugger : public DialogContainer
   // Make these friend classes, to ease communications with the debugger
   // Although it isn't enforced, these classes should use accessor methods
   // directly, and not touch the instance variables
-  friend class CartDebugWidget;
   friend class DebuggerDialog;
   friend class DebuggerParser;
   friend class EventHandler;
diff --git a/src/debugger/gui/CartDPCWidget.cxx b/src/debugger/gui/CartDPCWidget.cxx
index cf22e252d..159c42667 100644
--- a/src/debugger/gui/CartDPCWidget.cxx
+++ b/src/debugger/gui/CartDPCWidget.cxx
@@ -18,6 +18,7 @@
 //============================================================================
 
 #include "CartDPC.hxx"
+#include "DataGridWidget.hxx"
 #include "PopUpWidget.hxx"
 #include "CartDPCWidget.hxx"
 
@@ -59,6 +60,98 @@ CartridgeDPCWidget::CartridgeDPCWidget(
                     font.getStringWidth("Set bank: "), kBankChanged);
   myBank->setTarget(this);
   addFocusWidget(myBank);
+  ypos += myLineHeight + 12;
+
+  // Data fetchers
+  int lwidth = font.getStringWidth("Data Fetchers: ");
+  new StaticTextWidget(boss, font, xpos, ypos, lwidth,
+        myFontHeight, "Data Fetchers: ", kTextAlignLeft);
+
+  // Top registers
+  lwidth = font.getStringWidth("Counter Registers: ");
+  xpos = 18;  ypos += myLineHeight + 8;
+  new StaticTextWidget(boss, font, xpos, ypos, lwidth,
+        myFontHeight, "Top Registers: ", kTextAlignLeft);
+  xpos += lwidth;
+
+  myTops = new DataGridWidget(boss, font, xpos, ypos-2, 8, 1, 2, 8, kBASE_16);
+  myTops->setTarget(this);
+  myTops->setEditable(false);
+
+  // Bottom registers
+  xpos = 18;  ypos += myLineHeight + 8;
+  new StaticTextWidget(boss, font, xpos, ypos, lwidth,
+        myFontHeight, "Bottom Registers: ", kTextAlignLeft);
+  xpos += lwidth;
+
+  myBottoms = new DataGridWidget(boss, font, xpos, ypos-2, 8, 1, 2, 8, kBASE_16);
+  myBottoms->setTarget(this);
+  myBottoms->setEditable(false);
+
+  // Counter registers
+  xpos = 18;  ypos += myLineHeight + 8;
+  new StaticTextWidget(boss, font, xpos, ypos, lwidth,
+        myFontHeight, "Counter Registers: ", kTextAlignLeft);
+  xpos += lwidth;
+
+  myCounters = new DataGridWidget(boss, font, xpos, ypos-2, 8, 1, 4, 16, kBASE_16_4);
+  myCounters->setTarget(this);
+  myCounters->setEditable(false);
+
+  // Flag registers
+  xpos = 18;  ypos += myLineHeight + 8;
+  new StaticTextWidget(boss, font, xpos, ypos, lwidth,
+        myFontHeight, "Bottom Registers: ", kTextAlignLeft);
+  xpos += lwidth;
+
+  myFlags = new DataGridWidget(boss, font, xpos, ypos-2, 8, 1, 2, 8, kBASE_16);
+  myFlags->setTarget(this);
+  myFlags->setEditable(false);
+
+  // Music mode
+  xpos = 10;  ypos += myLineHeight + 12;
+  lwidth = font.getStringWidth("Music mode (DF5/DF6/DF7): ");
+  new StaticTextWidget(boss, font, xpos, ypos, lwidth,
+        myFontHeight, "Music mode (DF5/DF6/DF7): ", kTextAlignLeft);
+  xpos += lwidth;
+
+  myMusicMode = new DataGridWidget(boss, font, xpos, ypos-2, 3, 1, 2, 8, kBASE_16);
+  myMusicMode->setTarget(this);
+  myMusicMode->setEditable(false);
+
+  // Current random number
+  xpos = 10;  ypos += myLineHeight + 8;
+  new StaticTextWidget(boss, font, xpos, ypos, lwidth,
+        myFontHeight, "Current random number: ", kTextAlignLeft);
+  xpos += lwidth;
+
+  myRandom = new DataGridWidget(boss, font, xpos, ypos-2, 1, 1, 2, 8, kBASE_16);
+  myRandom->setTarget(this);
+  myRandom->setEditable(false);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+void CartridgeDPCWidget::saveOldState()
+{
+  myOldState.tops.clear();
+  myOldState.bottoms.clear();
+  myOldState.counters.clear();
+  myOldState.flags.clear();
+  myOldState.music.clear();
+
+  for(int i = 0; i < 8; ++i)
+  {
+    myOldState.tops.push_back(myCart.myTops[i]);
+    myOldState.bottoms.push_back(myCart.myBottoms[i]);
+    myOldState.counters.push_back(myCart.myCounters[i]);
+    myOldState.flags.push_back(myCart.myFlags[i]);
+  }
+  for(int i = 0; i < 3; ++i)
+  {
+    myOldState.music.push_back(myCart.myMusicMode[i]);
+  }
+
+  myOldState.random = myCart.myRandomNumber;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -66,6 +159,54 @@ void CartridgeDPCWidget::loadConfig()
 {
   myBank->setSelected(myCart.myCurrentBank);
 
+  // Get registers, using change tracking
+  IntArray alist;
+  IntArray vlist;
+  BoolArray changed;
+
+  alist.clear();  vlist.clear();  changed.clear();
+  for(int i = 0; i < 8; ++i)
+  {
+    alist.push_back(0);  vlist.push_back(myCart.myTops[i]);
+    changed.push_back(myCart.myTops[i] != myOldState.tops[i]);
+  }
+  myTops->setList(alist, vlist, changed);
+  
+  alist.clear();  vlist.clear();  changed.clear();
+  for(int i = 0; i < 8; ++i)
+  {
+    alist.push_back(0);  vlist.push_back(myCart.myBottoms[i]);
+    changed.push_back(myCart.myBottoms[i] != myOldState.bottoms[i]);
+  }
+  myBottoms->setList(alist, vlist, changed);
+
+  alist.clear();  vlist.clear();  changed.clear();
+  for(int i = 0; i < 8; ++i)
+  {
+    alist.push_back(0);  vlist.push_back(myCart.myCounters[i]);
+    changed.push_back(myCart.myCounters[i] != myOldState.counters[i]);
+  }
+  myCounters->setList(alist, vlist, changed);
+
+  alist.clear();  vlist.clear();  changed.clear();
+  for(int i = 0; i < 8; ++i)
+  {
+    alist.push_back(0);  vlist.push_back(myCart.myFlags[i]);
+    changed.push_back(myCart.myFlags[i] != myOldState.flags[i]);
+  }
+  myFlags->setList(alist, vlist, changed);
+
+  alist.clear();  vlist.clear();  changed.clear();
+  for(int i = 0; i < 3; ++i)
+  {
+    alist.push_back(0);  vlist.push_back(myCart.myMusicMode[i]);
+    changed.push_back(myCart.myMusicMode[i] != myOldState.music[i]);
+  }
+  myMusicMode->setList(alist, vlist, changed);
+
+  myRandom->setList(0, myCart.myRandomNumber,
+      myCart.myRandomNumber != myOldState.random);
+
   CartDebugWidget::loadConfig();
 }
 
diff --git a/src/debugger/gui/CartDPCWidget.hxx b/src/debugger/gui/CartDPCWidget.hxx
index 6958ceba5..9a43c4116 100644
--- a/src/debugger/gui/CartDPCWidget.hxx
+++ b/src/debugger/gui/CartDPCWidget.hxx
@@ -22,6 +22,7 @@
 
 class CartridgeDPC;
 class PopUpWidget;
+class DataGridWidget;
 
 #include "CartDebugWidget.hxx"
 
@@ -33,13 +34,34 @@ class CartridgeDPCWidget : public CartDebugWidget
                        CartridgeDPC& cart);
     virtual ~CartridgeDPCWidget() { }
 
+    void saveOldState();
+
     void loadConfig();
     void handleCommand(CommandSender* sender, int cmd, int data, int id);
 
+  private:
+    struct CartState {
+      ByteArray tops;
+      ByteArray bottoms;
+      IntArray counters;
+      ByteArray flags;
+      BoolArray music;
+      uInt8 random;
+    };
+
   private:
     CartridgeDPC& myCart;
     PopUpWidget* myBank;
 
+    DataGridWidget* myTops;
+    DataGridWidget* myBottoms;
+    DataGridWidget* myCounters;
+    DataGridWidget* myFlags;
+    DataGridWidget* myMusicMode;
+    DataGridWidget* myRandom;
+
+    CartState myState, myOldState;
+
     enum { kBankChanged = 'bkCH' };
 };
 
diff --git a/src/debugger/gui/CartDebugWidget.hxx b/src/debugger/gui/CartDebugWidget.hxx
index 732d6b338..60288de67 100644
--- a/src/debugger/gui/CartDebugWidget.hxx
+++ b/src/debugger/gui/CartDebugWidget.hxx
@@ -100,9 +100,13 @@ class CartDebugWidget : public Widget, public CommandSender
     // Inform the ROM Widget that the underlying cart has somehow changed
     void invalidate()
     {
-      Debugger::debugger().rom().invalidate();
+      sendCommand(RomWidget::kInvalidateListing, -1, -1);
     }
 
+    // Some carts need to save old state in the debugger, so that we can
+    // implement change tracking; most carts probably won't do anything here
+    virtual void saveOldState() { }
+
     virtual void loadConfig() { myDesc->setSelected(0); }
     virtual void handleCommand(CommandSender* sender, int cmd, int data, int id) { };
 
diff --git a/src/debugger/gui/CpuWidget.cxx b/src/debugger/gui/CpuWidget.cxx
index 2f7cc80c6..b00b257e5 100644
--- a/src/debugger/gui/CpuWidget.cxx
+++ b/src/debugger/gui/CpuWidget.cxx
@@ -138,7 +138,7 @@ void CpuWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
 
   switch(cmd)
   {
-    case kDGItemDataChangedCmd:
+    case DataGridWidget::kItemDataChangedCmd:
       switch(id)
       {
         case kPCRegID:
@@ -190,7 +190,7 @@ void CpuWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
       }
       break;
 
-    case kTWItemDataChangedCmd:
+    case ToggleWidget::kItemDataChangedCmd:
     {
       bool state = myPSRegister->getSelectedState();
 
diff --git a/src/debugger/gui/DataGridWidget.cxx b/src/debugger/gui/DataGridWidget.cxx
index ff22ab4c6..c30e49728 100644
--- a/src/debugger/gui/DataGridWidget.cxx
+++ b/src/debugger/gui/DataGridWidget.cxx
@@ -60,11 +60,17 @@ DataGridWidget::DataGridWidget(GuiObject* boss, const GUI::Font& font,
   // _textcolorhi to erase it
   _caretInverse = true;
 
-  // Make sure hilite list contains all false values
+  // Make sure all lists contain some default values
   _hiliteList.clear();
   int size = _rows * _cols;
   while(size--)
+  {
+    _addrList.push_back(0);
+    _valueList.push_back(0);
+    _valueStringList.push_back("");
+    _changedList.push_back(0);
     _hiliteList.push_back(false);
+  }
 
   // Set lower and upper bounds to sane values
   setRange(0, 1 << bits);
@@ -100,7 +106,6 @@ cerr << "alist.size() = "     << alist.size()
   assert(size == _rows * _cols);
 
   _addrList.clear();
-  _addrStringList.clear();
   _valueList.clear();
   _valueStringList.clear();
   _changedList.clear();
@@ -127,7 +132,7 @@ cerr << "_addrList.size() = "     << _addrList.size()
   _editMode = false;
 
   // Send item selected signal for starting with cell 0
-  sendCommand(kDGSelectionChangedCmd, _selectedItem, _id);
+  sendCommand(DataGridWidget::kSelectionChangedCmd, _selectedItem, _id);
 
   setDirty(); draw();
 }
@@ -200,7 +205,7 @@ void DataGridWidget::setValue(int position, int value, bool changed)
     _changedList[position] = changed;
     _valueList[position] = value;
 
-    sendCommand(kDGItemDataChangedCmd, position, _id);
+    sendCommand(DataGridWidget::kItemDataChangedCmd, position, _id);
 
     setDirty(); draw();
   }
@@ -234,7 +239,7 @@ void DataGridWidget::handleMouseDown(int x, int y, int button, int clickCount)
     _currentRow = _selectedItem / _cols;
     _currentCol = _selectedItem - (_currentRow * _cols);
 
-    sendCommand(kDGSelectionChangedCmd, _selectedItem, _id);
+    sendCommand(DataGridWidget::kSelectionChangedCmd, _selectedItem, _id);
     setDirty(); draw();
   }
 }
@@ -246,7 +251,7 @@ void DataGridWidget::handleMouseUp(int x, int y, int button, int clickCount)
   // send the double click command
   if (clickCount == 2 && (_selectedItem == findItem(x, y)))
   {
-    sendCommand(kDGItemDoubleClickedCmd, _selectedItem, _id);
+    sendCommand(DataGridWidget::kItemDoubleClickedCmd, _selectedItem, _id);
 
     // Start edit mode
     if(_editable && !_editMode)
@@ -464,7 +469,7 @@ bool DataGridWidget::handleKeyDown(StellaKey key, StellaMod mod, char ascii)
     _selectedItem = _currentRow*_cols + _currentCol;
 
     if(_selectedItem != oldItem)
-      sendCommand(kDGSelectionChangedCmd, _selectedItem, _id);
+      sendCommand(DataGridWidget::kSelectionChangedCmd, _selectedItem, _id);
 
     setDirty(); draw();
   }
diff --git a/src/debugger/gui/DataGridWidget.hxx b/src/debugger/gui/DataGridWidget.hxx
index d64297132..a8ed9334d 100644
--- a/src/debugger/gui/DataGridWidget.hxx
+++ b/src/debugger/gui/DataGridWidget.hxx
@@ -33,17 +33,18 @@ class ScrollBarWidget;
 #include "Array.hxx"
 #include "Rect.hxx"
 
-// Some special commands
-enum {
-  kDGItemDoubleClickedCmd = 'DGdb',
-  kDGItemActivatedCmd     = 'DGac',
-  kDGItemDataChangedCmd   = 'DGch',
-  kDGSelectionChangedCmd  = 'DGsc'
-};
-
 /* DataGridWidget */
 class DataGridWidget : public EditableWidget
 {
+  public:
+    // Commands emitted by this commandsender
+    enum {
+      kItemDoubleClickedCmd = 'DGdb',
+      kItemActivatedCmd     = 'DGac',
+      kItemDataChangedCmd   = 'DGch',
+      kSelectionChangedCmd  = 'DGsc'
+    };
+
   public:
     DataGridWidget(GuiObject* boss, const GUI::Font& font,
                    int x, int y, int cols, int rows,
@@ -120,7 +121,6 @@ class DataGridWidget : public EditableWidget
 
     IntArray    _addrList;
     IntArray    _valueList;
-    StringList  _addrStringList;
     StringList  _valueStringList;
     BoolArray   _changedList;
     BoolArray   _hiliteList;
diff --git a/src/debugger/gui/DebuggerDialog.cxx b/src/debugger/gui/DebuggerDialog.cxx
index f6338b171..03975bf7d 100644
--- a/src/debugger/gui/DebuggerDialog.cxx
+++ b/src/debugger/gui/DebuggerDialog.cxx
@@ -147,6 +147,10 @@ void DebuggerDialog::handleCommand(CommandSender* sender, int cmd,
       doExitRom();
       break;
 
+    case RomWidget::kInvalidateListing:
+      myRom->invalidate();
+      break;
+
     default:
       Dialog::handleCommand(sender, cmd, data, id);
   }
diff --git a/src/debugger/gui/DebuggerDialog.hxx b/src/debugger/gui/DebuggerDialog.hxx
index 3f63a5b39..ada9eff7f 100644
--- a/src/debugger/gui/DebuggerDialog.hxx
+++ b/src/debugger/gui/DebuggerDialog.hxx
@@ -53,6 +53,7 @@ class DebuggerDialog : public Dialog
     TiaOutputWidget& tiaOutput() { return *myTiaOutput;    }
     TiaZoomWidget& tiaZoom()     { return *myTiaZoom;      }
     RomWidget& rom()             { return *myRom;          }
+    CartDebugWidget& cartDebug() { return *myCartDebug;    }
     EditTextWidget& message()    { return *myMessageBox;   }
     ButtonWidget& rewindButton() { return *myRewindButton; }
 
diff --git a/src/debugger/gui/RamWidget.cxx b/src/debugger/gui/RamWidget.cxx
index 25845016c..d4b9f7d50 100644
--- a/src/debugger/gui/RamWidget.cxx
+++ b/src/debugger/gui/RamWidget.cxx
@@ -164,7 +164,7 @@ void RamWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
   const CartState& state = (CartState&) dbg.getState();
   switch(cmd)
   {
-    case kDGItemDataChangedCmd:
+    case DataGridWidget::kItemDataChangedCmd:
     {
       addr  = myRamGrid->getSelectedAddr();
       value = myRamGrid->getSelectedValue();
@@ -189,7 +189,7 @@ void RamWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
       break;
     }
 
-    case kDGSelectionChangedCmd:
+    case DataGridWidget::kSelectionChangedCmd:
     {
       addr  = myRamGrid->getSelectedAddr();
       value = myRamGrid->getSelectedValue();
diff --git a/src/debugger/gui/RiotWidget.cxx b/src/debugger/gui/RiotWidget.cxx
index 42f0a4c68..8cf967fb7 100644
--- a/src/debugger/gui/RiotWidget.cxx
+++ b/src/debugger/gui/RiotWidget.cxx
@@ -320,7 +320,7 @@ void RiotWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
 
   switch(cmd)
   {
-    case kDGItemDataChangedCmd:
+    case DataGridWidget::kItemDataChangedCmd:
       switch(id)
       {
         case kTimWriteID:
@@ -343,7 +343,7 @@ void RiotWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
       }
       break;
 
-    case kTWItemDataChangedCmd:
+    case ToggleWidget::kItemDataChangedCmd:
       switch(id)
       {
         case kSWCHABitsID:
diff --git a/src/debugger/gui/RomWidget.cxx b/src/debugger/gui/RomWidget.cxx
index f1a537025..1d7118ea1 100644
--- a/src/debugger/gui/RomWidget.cxx
+++ b/src/debugger/gui/RomWidget.cxx
@@ -202,7 +202,7 @@ void RomWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
       break;  // kCMenuItemSelectedCmd
     }
 
-    case kDGItemDataChangedCmd:
+    case DataGridWidget::kItemDataChangedCmd:
       setBank(myBank->getSelectedValue());
       break;
 
diff --git a/src/debugger/gui/RomWidget.hxx b/src/debugger/gui/RomWidget.hxx
index 4de51a043..ff32b9e53 100644
--- a/src/debugger/gui/RomWidget.hxx
+++ b/src/debugger/gui/RomWidget.hxx
@@ -38,6 +38,13 @@ class StringList;
 
 class RomWidget : public Widget, public CommandSender
 {
+  public:
+    enum {
+      kResolveDataChanged = 'ACrd',
+      kRomNameEntered     = 'RWrn',
+      kInvalidateListing  = 'INli'
+    };
+
   public:
     RomWidget(GuiObject* boss, const GUI::Font& font, int x, int y, int w, int h);
     virtual ~RomWidget();
@@ -58,11 +65,6 @@ class RomWidget : public Widget, public CommandSender
     void saveROM(const string& rom);
 
   private:
-    enum {
-      kResolveDataChanged = 'ACrd',
-      kRomNameEntered  = 'RWrn'
-    };
-
     RomListWidget*   myRomList;
     DataGridWidget*  myBank;
     PopUpWidget*     myResolveData;
diff --git a/src/debugger/gui/TiaWidget.cxx b/src/debugger/gui/TiaWidget.cxx
index e6d2e6de6..96b8019a7 100644
--- a/src/debugger/gui/TiaWidget.cxx
+++ b/src/debugger/gui/TiaWidget.cxx
@@ -585,7 +585,7 @@ void TiaWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
       tia.strobeCxclr();
       break;
 
-    case kDGItemDataChangedCmd:
+    case DataGridWidget::kItemDataChangedCmd:
       switch(id)
       {
         case kColorRegsID:
@@ -660,7 +660,7 @@ void TiaWidget::handleCommand(CommandSender* sender, int cmd, int data, int id)
       }
       break;
 
-    case kTWItemDataChangedCmd:
+    case ToggleWidget::kItemDataChangedCmd:
       switch(id)
       {
         case kGRP0ID:
diff --git a/src/debugger/gui/ToggleWidget.cxx b/src/debugger/gui/ToggleWidget.cxx
index 2c1535de1..cb07e136c 100644
--- a/src/debugger/gui/ToggleWidget.cxx
+++ b/src/debugger/gui/ToggleWidget.cxx
@@ -79,7 +79,7 @@ void ToggleWidget::handleMouseUp(int x, int y, int button, int clickCount)
   {
     _stateList[_selectedItem] = !_stateList[_selectedItem];
     _changedList[_selectedItem] = !_changedList[_selectedItem];
-    sendCommand(kTWItemDataChangedCmd, _selectedItem, _id);
+    sendCommand(ToggleWidget::kItemDataChangedCmd, _selectedItem, _id);
     setDirty(); draw();
   }
 }
@@ -193,7 +193,7 @@ bool ToggleWidget::handleKeyDown(StellaKey key, StellaMod mod, char ascii)
     {
       _stateList[_selectedItem] = !_stateList[_selectedItem];
       _changedList[_selectedItem] = !_changedList[_selectedItem];
-      sendCommand(kTWItemDataChangedCmd, _selectedItem, _id);
+      sendCommand(ToggleWidget::kItemDataChangedCmd, _selectedItem, _id);
     }
 
     setDirty(); draw();
diff --git a/src/debugger/gui/ToggleWidget.hxx b/src/debugger/gui/ToggleWidget.hxx
index 081ba82bd..1f78b2e66 100644
--- a/src/debugger/gui/ToggleWidget.hxx
+++ b/src/debugger/gui/ToggleWidget.hxx
@@ -27,15 +27,16 @@
 #include "Command.hxx"
 #include "Array.hxx"
 
-// Some special commands
-enum {
-  kTWItemDataChangedCmd   = 'TWch',
-  kTWSelectionChangedCmd  = 'TWsc'
-};
-
 /* ToggleWidget */
 class ToggleWidget : public Widget, public CommandSender
 {
+  public:
+    // Commands emitted by this commandsender
+    enum {
+      kItemDataChangedCmd   = 'TWch',
+      kSelectionChangedCmd  = 'TWsc'
+    };
+
   public:
     ToggleWidget(GuiObject* boss, const GUI::Font& font,
                  int x, int y, int cols, int rows);
diff --git a/src/emucore/CartDPC.cxx b/src/emucore/CartDPC.cxx
index 0ebf3beb0..0f5f8cc46 100644
--- a/src/emucore/CartDPC.cxx
+++ b/src/emucore/CartDPC.cxx
@@ -42,7 +42,7 @@ CartridgeDPC::CartridgeDPC(const uInt8* image, uInt32 size,
   myDisplayImage = myProgramImage + 8192;
 
   // Initialize the DPC data fetcher registers
-  for(uInt16 i = 0; i < 8; ++i)
+  for(int i = 0; i < 8; ++i)
     myTops[i] = myBottoms[i] = myCounters[i] = myFlags[i] = 0;
 
   // None of the data fetchers are in music mode
diff --git a/src/emucore/CartDPC.hxx b/src/emucore/CartDPC.hxx
index dfbed84c2..20b0de496 100644
--- a/src/emucore/CartDPC.hxx
+++ b/src/emucore/CartDPC.hxx
@@ -30,8 +30,12 @@ class System;
 
 /**
   Cartridge class used for Pitfall II.  There are two 4K program banks, a 
-  2K display bank, and the DPC chip.  For complete details on the DPC chip 
-  see David P. Crane's United States Patent Number 4,644,495.
+  2K display bank, and the DPC chip.  The bankswitching itself is the same
+  as F8 scheme (hotspots at $1FF8 and $1FF9).  DPC chip access is mapped to
+  $1000 - $1080 ($1000 - $103F is read port, $1040 - $107F is write port).
+
+  For complete details on the DPC chip see David P. Crane's United States
+  Patent Number 4,644,495.
 
   @author  Bradford W. Mott
   @version $Id$
diff --git a/src/emucore/CartDPCPlus.cxx b/src/emucore/CartDPCPlus.cxx
index 6e8b9172d..c52f27c2d 100644
--- a/src/emucore/CartDPCPlus.cxx
+++ b/src/emucore/CartDPCPlus.cxx
@@ -56,10 +56,7 @@ CartridgeDPCPlus::CartridgeDPCPlus(const uInt8* image, uInt32 size,
   // If the image is larger than 29K, we assume any excess at the
   // beginning is ARM code, and skip over it
   if(size > 29 * 1024)
-  {
-    int offset = size - 29 * 1024;
-    myProgramImage   += offset;
-  }
+    myProgramImage += (size - 29 * 1024);
 
 #ifdef THUMB_SUPPORT
   // Create Thumbulator ARM emulator
diff --git a/src/gui/Dialog.cxx b/src/gui/Dialog.cxx
index 2366edb70..9fbbaa417 100644
--- a/src/gui/Dialog.cxx
+++ b/src/gui/Dialog.cxx
@@ -582,7 +582,7 @@ bool Dialog::handleNavEvent(Event::Type e)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void Dialog::getTabIdForWidget(Widget* w)
 {
-  if(_myTabList.size() == 0)
+  if(_myTabList.size() == 0 || !w)
     return;
 
   for(uInt32 id = 0; id < _myTabList.size(); ++id)