diff --git a/SourceGen/AppSettings.cs b/SourceGen/AppSettings.cs
index 62abcd5..8ddbefc 100644
--- a/SourceGen/AppSettings.cs
+++ b/SourceGen/AppSettings.cs
@@ -111,6 +111,10 @@ namespace SourceGen {
         // ASCII chart viewer settings.
         public const string ASCCH_MODE = "ascch-mode1";
 
+        // Instruction chart settings.
+        public const string INSTCH_MODE = "instch-mode";
+        public const string INSTCH_SHOW_UNDOC = "instch-show-undoc";
+
         // Source generation settings.
         public const string SRCGEN_DEFAULT_ASM = "srcgen-default-asm";
         public const string SRCGEN_ADD_IDENT_COMMENT = "srcgen-add-ident-comment";
diff --git a/SourceGen/RuntimeData/Help/tools.html b/SourceGen/RuntimeData/Help/tools.html
index 9b909fc..99ca3fa 100644
--- a/SourceGen/RuntimeData/Help/tools.html
+++ b/SourceGen/RuntimeData/Help/tools.html
@@ -14,8 +14,9 @@
 
 <h2><a name="instruction-chart">Instruction Chart</a></h2>
 <p>This opens a window with a summary of all 256 opcodes.  The CPU can
-be chosen from the pop-up list at the bottom.  Undocumented opcodes are
-shown in italics.</p>
+be chosen from the pop-up list at the bottom.  Undocumented opcodes for
+6502/65C02 are shown in italics, and can be excluded from the list
+by unchecking the box at the bottom.</p>
 <p>The status flags affected by each instruction reflect their behavior
 on the 65816.  The only significant difference between 65816 and
 6502/65C02 is the way the BRK instruction affects the D and B/X flags.</p>
diff --git a/SourceGen/Tools/WpfGui/FileConcatenator.xaml b/SourceGen/Tools/WpfGui/FileConcatenator.xaml
index 57b88be..f4a856f 100644
--- a/SourceGen/Tools/WpfGui/FileConcatenator.xaml
+++ b/SourceGen/Tools/WpfGui/FileConcatenator.xaml
@@ -81,7 +81,7 @@ limitations under the License.
         </DataGrid>
 
         <StackPanel Grid.Row="1" Grid.Column="1" Margin="4,0,0,0">
-            <Button Width="90" Content="Add File..." Click="AddButton_Click"/>
+            <Button Width="90" Content="Add Files..." Click="AddButton_Click"/>
             <Button Width="90" Margin="0,4,0,0" Content="Remove File"
                     IsEnabled="{Binding IsRemoveEnabled}" Click="RemoveButton_Click"/>
             <Button Width="90" Margin="0,12,0,0" Content="Up"
diff --git a/SourceGen/Tools/WpfGui/InstructionChart.xaml b/SourceGen/Tools/WpfGui/InstructionChart.xaml
index 7c3863d..0e7542e 100644
--- a/SourceGen/Tools/WpfGui/InstructionChart.xaml
+++ b/SourceGen/Tools/WpfGui/InstructionChart.xaml
@@ -41,6 +41,9 @@ limitations under the License.
                       HorizontalAlignment="Left"
                       ItemsSource="{Binding CpuItems}" DisplayMemberPath="Name"
                       SelectionChanged="CpuSelectionComboBox_SelectionChanged"/>
+
+            <CheckBox Margin="32,4,0,0" Content="Show undocumented instructions"
+                      IsChecked="{Binding ShowUndocumented}"/>
         </StackPanel>
 
         <DataGrid DockPanel.Dock="Top" Name="instructionGrid"
@@ -57,8 +60,9 @@ limitations under the License.
                   SelectionMode="Extended"
                   VerticalScrollBarVisibility="Visible">
             <DataGrid.Resources>
-                <Style x:Key="undocCellStyle" TargetType="{x:Type DataGridCell}">
+                <Style x:Key="cellStyle" TargetType="{x:Type DataGridCell}">
                     <Style.Triggers>
+                        <!-- show undocumented opcodes differently -->
                         <DataTrigger Binding="{Binding Path=IsUndocumented}" Value="True">
                             <Setter Property="FontStyle" Value="Italic"/>
                             <Setter Property="Foreground"
@@ -70,7 +74,7 @@ limitations under the License.
             <DataGrid.Columns>
                 <DataGridTextColumn Header="Opc" Binding="{Binding Opcode}"/>
                 <DataGridTextColumn Header="Instruction" Binding="{Binding Sample}"
-                                    CellStyle="{StaticResource undocCellStyle}"/>
+                                    CellStyle="{StaticResource cellStyle}"/>
                 <DataGridTextColumn Header="Flags" Binding="{Binding Flags}"/>
                 <DataGridTextColumn Header="Cyc" Binding="{Binding Cycles}"/>
                 <DataGridTextColumn Header="Description" Binding="{Binding ShortDesc}"
diff --git a/SourceGen/Tools/WpfGui/InstructionChart.xaml.cs b/SourceGen/Tools/WpfGui/InstructionChart.xaml.cs
index 3cacb86..f6e5cd5 100644
--- a/SourceGen/Tools/WpfGui/InstructionChart.xaml.cs
+++ b/SourceGen/Tools/WpfGui/InstructionChart.xaml.cs
@@ -45,6 +45,12 @@ namespace SourceGen.Tools.WpfGui {
         }
         public CpuItem[] CpuItems { get; private set; }
 
+        public bool ShowUndocumented {
+            get { return mShowUndocumented; }
+            set { mShowUndocumented = value; OnPropertyChanged(); UpdateControls(); }
+        }
+        private bool mShowUndocumented;
+
         /// <summary>
         /// Item for main list.
         /// </summary>
@@ -104,9 +110,11 @@ namespace SourceGen.Tools.WpfGui {
         }
 
         public void Window_Loaded(object sender, RoutedEventArgs e) {
-            // Restore chart mode setting.
+            // Restore chart settings.
             CpuDef.CpuType type = (CpuDef.CpuType)AppSettings.Global.GetEnum(
-                AppSettings.ASCCH_MODE, typeof(CpuDef.CpuType), (int)CpuDef.CpuType.Cpu6502);
+                AppSettings.INSTCH_MODE, typeof(CpuDef.CpuType), (int)CpuDef.CpuType.Cpu6502);
+            ShowUndocumented = AppSettings.Global.GetBool(AppSettings.INSTCH_SHOW_UNDOC, true);
+
             int index = 0;
             for (int i = 0; i < CpuItems.Length; i++) {
                 if (CpuItems[i].Type == type) {
@@ -137,14 +145,18 @@ namespace SourceGen.Tools.WpfGui {
             }
 
             // Push current choice to settings.
-            AppSettings.Global.SetEnum(AppSettings.ASCCH_MODE, typeof(CpuDef.CpuType),
+            AppSettings.Global.SetEnum(AppSettings.INSTCH_MODE, typeof(CpuDef.CpuType),
                 (int)item.Type);
+            AppSettings.Global.SetBool(AppSettings.INSTCH_SHOW_UNDOC, mShowUndocumented);
 
             // Populate the items source.
             InstructionItems.Clear();
             CpuDef cpuDef = CpuDef.GetBestMatch(item.Type, true, false);
             for (int opc = 0; opc < 256; opc++) {
                 OpDef op = cpuDef[opc];
+                if (!mShowUndocumented && op.IsUndocumented) {
+                    continue;
+                }
 
                 int opLen = op.GetLength(StatusFlags.AllIndeterminate);
                 string sampleValue = "$12";
@@ -155,7 +167,8 @@ namespace SourceGen.Tools.WpfGui {
                 } else if (opLen == 4) {
                     sampleValue = "$123456";
                 }
-                string instrSample = op.Mnemonic + " " +
+                string instrSample = mFormatter.FormatMnemonic(op.Mnemonic,
+                        OpDef.WidthDisambiguation.None) + " " +
                     mFormatter.FormatOperand(op, sampleValue, OpDef.WidthDisambiguation.None);