diff --git a/src/main/java/de/neemann/digital/analyse/TruthTable.java b/src/main/java/de/neemann/digital/analyse/TruthTable.java
index e865f7f7c..329d668ac 100644
--- a/src/main/java/de/neemann/digital/analyse/TruthTable.java
+++ b/src/main/java/de/neemann/digital/analyse/TruthTable.java
@@ -16,15 +16,17 @@ import de.neemann.digital.analyse.quinemc.BoolTable;
 import de.neemann.digital.analyse.quinemc.BoolTableByteArray;
 import de.neemann.digital.analyse.quinemc.ThreeStateValue;
 import de.neemann.digital.lang.Lang;
+import de.neemann.digital.undo.Copyable;
 
 import java.io.*;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.Collection;
 
 /**
  * The description of a truth table.
  */
-public class TruthTable {
+public class TruthTable implements Copyable<TruthTable> {
 
     private final ArrayList<Variable> variables;
     private final ArrayList<Result> results;
@@ -148,6 +150,29 @@ public class TruthTable {
         }
     }
 
+    private TruthTable(TruthTable truthTable) {
+        variables = new ArrayList<>(truthTable.variables.size());
+        for (Variable v : truthTable.variables)
+            variables.add(new Variable(v.getIdentifier()));
+        results = new ArrayList<>();
+        for (int i = 0; i < truthTable.getResultCount(); i++) {
+            Result result = truthTable.results.get(i);
+            addResult(result.getName(), new BoolTableByteArray(result.values));
+        }
+        this.modelAnalyzerInfo = truthTable.modelAnalyzerInfo;
+    }
+
+    /**
+     * Clears the table and sets the given variables
+     *
+     * @param vars the variables to use
+     */
+    public void clear(Collection<? extends Variable> vars) {
+        variables.clear();
+        variables.addAll(vars);
+        results.clear();
+    }
+
     /**
      * Returns the number of rows
      *
@@ -489,6 +514,31 @@ public class TruthTable {
         return modelAnalyzerInfo;
     }
 
+    @Override
+    public TruthTable createDeepCopy() {
+        return new TruthTable(this);
+    }
+
+    /**
+     * @return the names of all input variables
+     */
+    public ArrayList<String> getVarNames() {
+        ArrayList<String> names = new ArrayList<>();
+        for (Variable v : variables)
+            names.add(v.getIdentifier());
+        return names;
+    }
+
+    /**
+     * @return the names of al result variables
+     */
+    public ArrayList<String> getResultNames() {
+        ArrayList<String> names = new ArrayList<>();
+        for (Result r : results)
+            names.add(r.getName());
+        return names;
+    }
+
     /**
      * A single result column
      */
diff --git a/src/main/java/de/neemann/digital/analyse/TruthTableTableModel.java b/src/main/java/de/neemann/digital/analyse/TruthTableTableModel.java
index 0b8bc348b..c76925f13 100644
--- a/src/main/java/de/neemann/digital/analyse/TruthTableTableModel.java
+++ b/src/main/java/de/neemann/digital/analyse/TruthTableTableModel.java
@@ -6,6 +6,8 @@
 package de.neemann.digital.analyse;
 
 import de.neemann.digital.analyse.quinemc.BoolTable;
+import de.neemann.digital.undo.ModifyException;
+import de.neemann.digital.undo.UndoManager;
 
 import javax.swing.event.TableModelEvent;
 import javax.swing.event.TableModelListener;
@@ -23,31 +25,31 @@ public class TruthTableTableModel implements TableModel {
      */
     public static final String[] STATENAMES = new String[]{"0", "1", "x"};
 
-    private final TruthTable truthTable;
     private final ArrayList<TableModelListener> listeners = new ArrayList<>();
+    private final UndoManager<TruthTable> undoManager;
 
     /**
      * Creates a new instance
      *
-     * @param truthTable the truthTable which is to visualize
+     * @param undoManager the undoManager
      */
-    public TruthTableTableModel(TruthTable truthTable) {
-        this.truthTable = truthTable;
+    public TruthTableTableModel(UndoManager<TruthTable> undoManager) {
+        this.undoManager = undoManager;
     }
 
     @Override
     public int getRowCount() {
-        return truthTable.getRows();
+        return undoManager.getActual().getRows();
     }
 
     @Override
     public int getColumnCount() {
-        return truthTable.getCols();
+        return undoManager.getActual().getCols();
     }
 
     @Override
     public String getColumnName(int columnIndex) {
-        return truthTable.getColumnName(columnIndex);
+        return undoManager.getActual().getColumnName(columnIndex);
     }
 
     @Override
@@ -57,35 +59,52 @@ public class TruthTableTableModel implements TableModel {
 
     @Override
     public boolean isCellEditable(int rowIndex, int columnIndex) {
-        return truthTable.isEditable(columnIndex);
+        return undoManager.getActual().isEditable(columnIndex);
     }
 
     @Override
     public Object getValueAt(int rowIndex, int columnIndex) {
-        return truthTable.getValue(rowIndex, columnIndex);
+        return undoManager.getActual().getValue(rowIndex, columnIndex);
     }
 
     @Override
     public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
         if (aValue instanceof Integer)
-            truthTable.setValue(rowIndex, columnIndex, (Integer) aValue);
+            setValue(rowIndex, columnIndex, (Integer) aValue);
         if (aValue instanceof String) {
             if (aValue.toString().equals("0"))
-                truthTable.setValue(rowIndex, columnIndex, 0);
+                setValue(rowIndex, columnIndex, 0);
             else if (aValue.toString().equals("1"))
-                truthTable.setValue(rowIndex, columnIndex, 1);
+                setValue(rowIndex, columnIndex, 1);
             else
-                truthTable.setValue(rowIndex, columnIndex, 2);
+                setValue(rowIndex, columnIndex, 2);
         }
         fireModelEvent(rowIndex);
     }
 
+    private void setValue(int rowIndex, int columnIndex, int val) {
+        try {
+            undoManager.apply(truthTable -> truthTable.setValue(rowIndex, columnIndex, val));
+        } catch (ModifyException e) {
+            e.printStackTrace();
+        }
+    }
+
     private void fireModelEvent(int rowIndex) {
         TableModelEvent e = new TableModelEvent(this, rowIndex);
         for (TableModelListener l : listeners)
             l.tableChanged(e);
     }
 
+    /**
+     * Fires a structural table change
+     */
+    public void fireTableChanged() {
+        TableModelEvent e = new TableModelEvent(this, HEADER_ROW);
+        for (TableModelListener l : listeners)
+            l.tableChanged(e);
+    }
+
     @Override
     public void addTableModelListener(TableModelListener l) {
         listeners.add(l);
@@ -95,13 +114,6 @@ public class TruthTableTableModel implements TableModel {
     public void removeTableModelListener(TableModelListener l) {
     }
 
-    /**
-     * @return the truth table used by this model
-     */
-    public TruthTable getTable() {
-        return truthTable;
-    }
-
     /**
      * Sets the column name
      *
@@ -109,7 +121,11 @@ public class TruthTableTableModel implements TableModel {
      * @param name        the new name
      */
     public void setColumnName(int columnIndex, String name) {
-        truthTable.setColumnName(columnIndex, name);
+        try {
+            undoManager.apply(truthTable -> truthTable.setColumnName(columnIndex, name));
+        } catch (ModifyException e) {
+            e.printStackTrace();
+        }
         fireModelEvent(HEADER_ROW);
     }
 
@@ -121,18 +137,26 @@ public class TruthTableTableModel implements TableModel {
      */
     public void incValue(BoolTable boolTable, int row) {
         int col = -1;
-        for (int i = 0; i < truthTable.getResultCount(); i++) {
-            if (truthTable.getResult(i) == boolTable) {
+        TruthTable tt = undoManager.getActual();
+        for (int i = 0; i < tt.getResultCount(); i++) {
+            if (tt.getResult(i) == boolTable) {
                 col = i;
                 break;
             }
         }
         if (col >= 0) {
-            col += truthTable.getVars().size();
-            int value = truthTable.getValue(row, col);
+            col += tt.getVars().size();
+            int value = tt.getValue(row, col);
             if (value == 2) value = 0;
             else value++;
             setValueAt(value, row, col);
         }
     }
+
+    /**
+     * @return the truth table shown
+     */
+    public TruthTable getTable() {
+        return undoManager.getActual();
+    }
 }
diff --git a/src/main/java/de/neemann/digital/analyse/quinemc/BoolTableByteArray.java b/src/main/java/de/neemann/digital/analyse/quinemc/BoolTableByteArray.java
index 3228e05a5..5ed3f589d 100644
--- a/src/main/java/de/neemann/digital/analyse/quinemc/BoolTableByteArray.java
+++ b/src/main/java/de/neemann/digital/analyse/quinemc/BoolTableByteArray.java
@@ -32,6 +32,17 @@ public class BoolTableByteArray implements BoolTable {
         this.table = table;
     }
 
+    /**
+     * Creates a new instance
+     *
+     * @param values the values to initialize the table
+     */
+    public BoolTableByteArray(BoolTable values) {
+        table = new byte[values.size()];
+        for (int i = 0; i < values.size(); i++)
+            table[i] = (byte) values.get(i).asInt();
+    }
+
     @Override
     public int size() {
         return table.length;
diff --git a/src/main/java/de/neemann/digital/gui/components/table/LaTeXExpressionListener.java b/src/main/java/de/neemann/digital/gui/components/table/LaTeXExpressionListener.java
index 001182e0a..883680621 100644
--- a/src/main/java/de/neemann/digital/gui/components/table/LaTeXExpressionListener.java
+++ b/src/main/java/de/neemann/digital/gui/components/table/LaTeXExpressionListener.java
@@ -5,7 +5,7 @@
  */
 package de.neemann.digital.gui.components.table;
 
-import de.neemann.digital.analyse.TruthTableTableModel;
+import de.neemann.digital.analyse.TruthTable;
 import de.neemann.digital.analyse.expression.Expression;
 import de.neemann.digital.analyse.expression.ExpressionException;
 import de.neemann.digital.analyse.expression.NamedExpression;
@@ -15,10 +15,10 @@ import de.neemann.digital.draw.graphics.text.formatter.LaTeXFormatter;
 final class LaTeXExpressionListener implements ExpressionListener {
     private final StringBuilder sb;
 
-    LaTeXExpressionListener(TruthTableTableModel model) throws ExpressionException {
+    LaTeXExpressionListener(TruthTable truthTable) throws ExpressionException {
         sb = new StringBuilder();
-        if (model.getTable().getRows() <= 256) {
-            String text = new TruthTableFormatterLaTeX().format(model.getTable());
+        if (truthTable.getRows() <= 256) {
+            String text = new TruthTableFormatterLaTeX().format(truthTable);
             sb.append(text);
         }
         sb.append("\\begin{eqnarray*}\n");
diff --git a/src/main/java/de/neemann/digital/gui/components/table/ProgressDialog.java b/src/main/java/de/neemann/digital/gui/components/table/ProgressDialog.java
index 957ba956c..a12a9b42b 100644
--- a/src/main/java/de/neemann/digital/gui/components/table/ProgressDialog.java
+++ b/src/main/java/de/neemann/digital/gui/components/table/ProgressDialog.java
@@ -27,7 +27,7 @@ public class ProgressDialog extends JDialog implements ExpressionCreator.Progres
         super(tableDialog, false);
         setDefaultCloseOperation(DISPOSE_ON_CLOSE);
 
-        bar = new JProgressBar(0, tableDialog.getModel().getTable().getResultCount());
+        bar = new JProgressBar(0, tableDialog.getUndoManager().getActual().getResultCount());
         int b = Screen.getInstance().getFontSize();
         bar.setBorder(BorderFactory.createEmptyBorder(b, b, b, b));
         final JLabel label = new JLabel(Lang.get("msg_optimizationInProgress"));
diff --git a/src/main/java/de/neemann/digital/gui/components/table/ReorderInputs.java b/src/main/java/de/neemann/digital/gui/components/table/ReorderInputs.java
index dc01a4a0f..80381ec96 100644
--- a/src/main/java/de/neemann/digital/gui/components/table/ReorderInputs.java
+++ b/src/main/java/de/neemann/digital/gui/components/table/ReorderInputs.java
@@ -55,10 +55,9 @@ public class ReorderInputs {
     /**
      * Creates a new table matching the actual state of the items
      *
-     * @return the new table
      * @throws ExpressionException ExpressionException
      */
-    public TruthTable reorder() throws ExpressionException {
+    public void reorder() throws ExpressionException {
         ArrayList<Variable> newVars = new ArrayList<>();
         ArrayList<Variable> deletedVars = new ArrayList<>(table.getVars());
 
@@ -79,21 +78,20 @@ public class ReorderInputs {
         if (newVars.size() < 2)
             throw new ExpressionException(Lang.get("err_tableBecomesToSmall"));
 
-        TruthTable newTable = new TruthTable(newVars);
-        newTable.setModelAnalyzerInfo(table.getModelAnalyzerInfo());
-        for (int j = 0; j < table.getResultCount(); j++)
-            newTable.addResult(table.getResultName(j));
+        TruthTable oldTable = this.table.createDeepCopy();
 
-        ContextFiller fc = new ContextFiller(newTable.getVars());
+        table.clear(newVars);
+        for (int j = 0; j < oldTable.getResultCount(); j++)
+            table.addResult(oldTable.getResultName(j));
+
+        ContextFiller fc = new ContextFiller(table.getVars());
         for (Variable v : deletedVars)
             fc.set(v, false);
 
-        for (int row = 0; row < newTable.getRows(); row++) {
+        for (int row = 0; row < table.getRows(); row++) {
             fc.setContextTo(row);
-            for (int t = 0; t < newTable.getResultCount(); t++)
-                newTable.setByContext(t, fc, table.getByContext(t, fc));
+            for (int t = 0; t < table.getResultCount(); t++)
+                table.setByContext(t, fc, oldTable.getByContext(t, fc));
         }
-
-        return newTable;
     }
 }
diff --git a/src/main/java/de/neemann/digital/gui/components/table/ReorderOutputs.java b/src/main/java/de/neemann/digital/gui/components/table/ReorderOutputs.java
index 1f45585a6..ecb17b8c3 100644
--- a/src/main/java/de/neemann/digital/gui/components/table/ReorderOutputs.java
+++ b/src/main/java/de/neemann/digital/gui/components/table/ReorderOutputs.java
@@ -53,23 +53,20 @@ public class ReorderOutputs {
     /**
      * Creates a new table matching the actual state of the items
      *
-     * @return the new table
      * @throws ExpressionException ExpressionException
      */
-    public TruthTable reorder() throws ExpressionException {
-        TruthTable newTable = new TruthTable(table.getVars());
-        newTable.setModelAnalyzerInfo(table.getModelAnalyzerInfo());
+    public void reorder() throws ExpressionException {
+        TruthTable oldTable = table.createDeepCopy();
+        table.clear(oldTable.getVars());
         for (String name : names) {
-            for (int i = 0; i < table.getResultCount(); i++)
-                if (table.getResultName(i).equals(name)) {
-                    newTable.addResult(table.getResultName(i), table.getResult(i));
+            for (int i = 0; i < oldTable.getResultCount(); i++)
+                if (oldTable.getResultName(i).equals(name)) {
+                    table.addResult(oldTable.getResultName(i), oldTable.getResult(i));
                     break;
                 }
         }
 
-        if (newTable.getResultCount() < 1)
+        if (table.getResultCount() < 1)
             throw new ExpressionException(Lang.get("err_oneResultIsRequired"));
-
-        return newTable;
     }
 }
diff --git a/src/main/java/de/neemann/digital/gui/components/table/TableDialog.java b/src/main/java/de/neemann/digital/gui/components/table/TableDialog.java
index 7d4a42c01..fb0ff162d 100644
--- a/src/main/java/de/neemann/digital/gui/components/table/TableDialog.java
+++ b/src/main/java/de/neemann/digital/gui/components/table/TableDialog.java
@@ -41,6 +41,8 @@ import de.neemann.digital.gui.components.table.hardware.GenerateCUPL;
 import de.neemann.digital.gui.components.table.hardware.GenerateFile;
 import de.neemann.digital.gui.components.table.hardware.HardwareDescriptionGenerator;
 import de.neemann.digital.lang.Lang;
+import de.neemann.digital.undo.ModifyException;
+import de.neemann.digital.undo.UndoManager;
 import de.neemann.gui.*;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -66,7 +68,7 @@ import java.util.prefs.Preferences;
 import static de.neemann.digital.analyse.ModelAnalyser.addOne;
 
 /**
- *
+ * The dialog used to show the truth table.
  */
 public class TableDialog extends JDialog {
     private static final Logger LOGGER = LoggerFactory.getLogger(TableDialog.class);
@@ -102,15 +104,16 @@ public class TableDialog extends JDialog {
     private final ToolTipAction karnaughMenuAction;
     private final HashMap<String, HardwareDescriptionGenerator> availGenerators = new HashMap<>();
     private final JMenu hardwareMenu;
+    private final TruthTableTableModel model;
     private JCheckBoxMenuItem createJK;
     private File filename;
-    private TruthTableTableModel model;
     private int columnIndex;
     private AllSolutionsDialog allSolutionsDialog;
     private ExpressionListenerStore lastGeneratedExpressions;
     private KarnaughMapDialog kvMap;
     private JMenuItem lastUsedGenratorMenuItem;
     private Mouse mouse = Mouse.getMouse();
+    private UndoManager<TruthTable> undoManager;
 
     /**
      * Creates a new instance
@@ -122,10 +125,15 @@ public class TableDialog extends JDialog {
      */
     public TableDialog(Window parent, TruthTable truthTable, ElementLibrary library, File filename) {
         super(parent, Lang.get("win_table"));
+        undoManager = new UndoManager<>(truthTable);
         this.library = library;
         this.shapeFactory = library.getShapeFactory();
         this.filename = filename;
         setDefaultCloseOperation(DISPOSE_ON_CLOSE);
+
+        model = new TruthTableTableModel(undoManager);
+        model.addTableModelListener(new CalculationTableModelListener());
+
         kvMap = new KarnaughMapDialog(this, (boolTable, row) -> model.incValue(boolTable, row));
 
         statusBar = new ExpressionComponent();
@@ -182,63 +190,90 @@ public class TableDialog extends JDialog {
         }
         bar.add(sizeMenu);
 
-        JMenu columnsMenu = new JMenu(Lang.get("menu_table_columns"));
-        bar.add(columnsMenu);
-        columnsMenu.add(new ToolTipAction(Lang.get("menu_table_reorder_inputs")) {
+        JMenu edit = new JMenu(Lang.get("menu_edit"));
+        bar.add(edit);
+
+        addUndoRedo(edit);
+
+        edit.addSeparator();
+
+        edit.add(new ToolTipAction(Lang.get("menu_table_reorder_inputs")) {
             @Override
             public void actionPerformed(ActionEvent e) {
-                ReorderInputs ri = new ReorderInputs(model.getTable());
-                if (new ElementOrderer<>(TableDialog.this, Lang.get("menu_table_reorder_inputs"), ri.getItems())
+                ArrayList<String> varNames = undoManager.getActual().getVarNames();
+                if (new ElementOrderer<>(TableDialog.this, Lang.get("menu_table_reorder_inputs"), new ElementOrderer.ListOrder<>(varNames))
                         .addDeleteButton()
                         .addOkButton()
                         .showDialog()) {
+
                     try {
-                        setModel(new TruthTableTableModel(ri.reorder()));
-                    } catch (ExpressionException e1) {
+                        undoManager.apply(tt -> {
+                            try {
+                                new ReorderInputs(tt, varNames).reorder();
+                                tableChanged();
+                            } catch (ExpressionException ex) {
+                                throw new ModifyException("failed to reorder", ex);
+                            }
+                        });
+                    } catch (ModifyException e1) {
                         new ErrorMessage().addCause(e1).show(TableDialog.this);
                     }
                 }
             }
         }.createJMenuItem());
 
-        columnsMenu.add(new ToolTipAction(Lang.get("menu_table_columnsAddVariable")) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_columnsAddVariable")) {
             @Override
             public void actionPerformed(ActionEvent actionEvent) {
-                TruthTable t = model.getTable();
-                t.addVariable();
-                setModel(new TruthTableTableModel(t));
+                try {
+                    undoManager.apply(TruthTable::addVariable);
+                    tableChanged();
+                } catch (ModifyException e) {
+                    new ErrorMessage().addCause(e).show(TableDialog.this);
+                }
             }
         }.setToolTip(Lang.get("menu_table_columnsAddVariable_tt")).createJMenuItem());
 
-        columnsMenu.add(new ToolTipAction(Lang.get("menu_table_reorder_outputs")) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_reorder_outputs")) {
             @Override
             public void actionPerformed(ActionEvent e) {
-                ReorderOutputs ro = new ReorderOutputs(model.getTable());
-                if (new ElementOrderer<>(TableDialog.this, Lang.get("menu_table_reorder_outputs"), ro.getItems())
+                ArrayList<String> resultNames = undoManager.getActual().getResultNames();
+                if (new ElementOrderer<>(TableDialog.this, Lang.get("menu_table_reorder_outputs"), new ElementOrderer.ListOrder<>(resultNames))
                         .addDeleteButton()
                         .addOkButton()
                         .showDialog()) {
                     try {
-                        setModel(new TruthTableTableModel(ro.reorder()));
-                    } catch (ExpressionException e1) {
+                        undoManager.apply(tt -> {
+                            try {
+                                new ReorderOutputs(tt, resultNames).reorder();
+                                tableChanged();
+                            } catch (ExpressionException ex) {
+                                throw new ModifyException("failed to reorder", ex);
+                            }
+                        });
+                    } catch (ModifyException e1) {
                         new ErrorMessage().addCause(e1).show(TableDialog.this);
                     }
                 }
             }
         }.createJMenuItem());
 
-        columnsMenu.add(new ToolTipAction(Lang.get("menu_table_columnsAdd")) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_columnsAdd")) {
             @Override
             public void actionPerformed(ActionEvent actionEvent) {
-                TruthTable t = model.getTable();
-                t.addResult();
-                setModel(new TruthTableTableModel(t));
+                try {
+                    undoManager.apply(TruthTable::addResult);
+                    tableChanged();
+                } catch (ModifyException e) {
+                    new ErrorMessage().addCause(e).show(TableDialog.this);
+                }
+
             }
         }.setToolTip(Lang.get("menu_table_columnsAdd_tt")).createJMenuItem());
 
-        bar.add(columnsMenu);
+        edit.addSeparator();
 
-        bar.add(createSetMenu());
+        createSetMenuEntries(edit);
 
         hardwareMenu = createCreateMenu();
         bar.add(hardwareMenu);
@@ -256,14 +291,55 @@ public class TableDialog extends JDialog {
 
         setJMenuBar(bar);
 
-        setModel(new TruthTableTableModel(truthTable));
-
         getContentPane().add(new JScrollPane(table));
         getContentPane().add(statusBar, BorderLayout.SOUTH);
         pack();
         setLocationRelativeTo(parent);
     }
 
+    private void addUndoRedo(JMenu edit) {
+        final ToolTipAction undo = new ToolTipAction(Lang.get("menu_undo")) {
+            @Override
+            public void actionPerformed(ActionEvent actionEvent) {
+                if (undoManager.undoAvailable()) {
+                    try {
+                        undoManager.undo();
+                        tableChanged();
+                    } catch (ModifyException e) {
+                        new ErrorMessage().addCause(e).show(TableDialog.this);
+                    }
+                }
+            }
+        }.setAcceleratorCTRLplus("Z");
+        final ToolTipAction redo = new ToolTipAction(Lang.get("menu_redo")) {
+            @Override
+            public void actionPerformed(ActionEvent actionEvent) {
+                if (undoManager.redoAvailable()) {
+                    try {
+                        undoManager.redo();
+                        tableChanged();
+                    } catch (ModifyException e) {
+                        new ErrorMessage().addCause(e).show(TableDialog.this);
+                    }
+                }
+            }
+        }.setAcceleratorCTRLplus("Y");
+        edit.add(undo.createJMenuItem());
+        edit.add(redo.createJMenuItem());
+        undoManager.addListener(() -> {
+            undo.setEnabled(undoManager.undoAvailable());
+            redo.setEnabled(undoManager.redoAvailable());
+        });
+        undo.setEnabled(undoManager.undoAvailable());
+        redo.setEnabled(undoManager.redoAvailable());
+    }
+
+    void tableChanged() {
+        karnaughMenuAction.setEnabled(undoManager.getActual().getVars().size() <= 4);
+        calculateExpressions();
+        model.fireTableChanged();
+    }
+
     private void editColumnName(int columnIndex, Point pos) {
         ElementAttributes attr = new ElementAttributes();
         final String name = model.getColumnName(columnIndex);
@@ -290,7 +366,8 @@ public class TableDialog extends JDialog {
                     try {
                         File file = fc.getSelectedFile();
                         TruthTable truthTable = TruthTable.readFromFile(file);
-                        setModel(new TruthTableTableModel(truthTable));
+                        undoManager.setInitial(truthTable);
+                        tableChanged();
                         TableDialog.this.filename = file;
                     } catch (IOException e1) {
                         new ErrorMessage().addCause(e1).show(TableDialog.this);
@@ -308,7 +385,7 @@ public class TableDialog extends JDialog {
                 fc.setFileFilter(new FileNameExtensionFilter(Lang.get("msg_truthTable"), "tru"));
                 new SaveAsHelper(TableDialog.this, fc, "tru").checkOverwrite(
                         file -> {
-                            model.getTable().save(file);
+                            undoManager.getActual().save(file);
                             TableDialog.this.filename = file;
                         }
                 );
@@ -320,7 +397,7 @@ public class TableDialog extends JDialog {
             @Override
             public void actionPerformed(ActionEvent e) {
                 try {
-                    final LaTeXExpressionListener laTeXExpressionListener = new LaTeXExpressionListener(model);
+                    final LaTeXExpressionListener laTeXExpressionListener = new LaTeXExpressionListener(undoManager.getActual());
                     ExpressionListener expressionListener = laTeXExpressionListener;
                     if (createJK.isSelected())
                         expressionListener = new ExpressionListenerJK(expressionListener);
@@ -339,14 +416,14 @@ public class TableDialog extends JDialog {
             @Override
             public void actionPerformed(ActionEvent e) {
                 int res = JOptionPane.OK_OPTION;
-                if (model.getTable().getVars().size() > 20)
+                if (undoManager.getActual().getVars().size() > 20)
                     res = JOptionPane.showConfirmDialog(TableDialog.this, Lang.get("msg_tableHasManyRowsConfirm"));
                 if (res == JOptionPane.OK_OPTION) {
                     JFileChooser fc = new MyFileChooser();
                     if (TableDialog.this.filename != null)
                         fc.setSelectedFile(SaveAsHelper.checkSuffix(TableDialog.this.filename, "hex"));
                     new SaveAsHelper(TableDialog.this, fc, "hex")
-                            .checkOverwrite(file -> model.getTable().saveHex(file));
+                            .checkOverwrite(file -> undoManager.getActual().saveHex(file));
                 }
             }
         }.setToolTip(Lang.get("menu_table_exportHex_tt")).createJMenuItem());
@@ -361,49 +438,53 @@ public class TableDialog extends JDialog {
         return fileMenu;
     }
 
-    private JMenu createSetMenu() {
-        JMenu setMenu = new JMenu(Lang.get("menu_table_set"));
-        setMenu.add(new ToolTipAction(Lang.get("menu_table_setXTo0")) {
+    private void createSetMenuEntries(JMenu edit) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_setXTo0")) {
             @Override
             public void actionPerformed(ActionEvent e) {
                 modifyTable(v -> v > 1 ? 0 : v);
             }
         }.setToolTip(Lang.get("menu_table_setXTo0_tt")).createJMenuItem());
-        setMenu.add(new ToolTipAction(Lang.get("menu_table_setXTo1")) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_setXTo1")) {
             @Override
             public void actionPerformed(ActionEvent e) {
                 modifyTable(v -> v > 1 ? 1 : v);
             }
         }.setToolTip(Lang.get("menu_table_setXTo1_tt")).createJMenuItem());
-        setMenu.add(new ToolTipAction(Lang.get("menu_table_setAllToX")) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_setAllToX")) {
             @Override
             public void actionPerformed(ActionEvent e) {
                 modifyTable(v -> (byte) 2);
             }
         }.setToolTip(Lang.get("menu_table_setAllToX_tt")).createJMenuItem());
-        setMenu.add(new ToolTipAction(Lang.get("menu_table_setAllTo0")) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_setAllTo0")) {
             @Override
             public void actionPerformed(ActionEvent e) {
                 modifyTable(v -> (byte) 0);
             }
         }.setToolTip(Lang.get("menu_table_setAllTo0_tt")).createJMenuItem());
-        setMenu.add(new ToolTipAction(Lang.get("menu_table_setAllTo1")) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_setAllTo1")) {
             @Override
             public void actionPerformed(ActionEvent e) {
                 modifyTable(v -> (byte) 1);
             }
         }.setToolTip(Lang.get("menu_table_setAllTo1_tt")).createJMenuItem());
-        setMenu.add(new ToolTipAction(Lang.get("menu_table_invert")) {
+        edit.add(new ToolTipAction(Lang.get("menu_table_invert")) {
             @Override
             public void actionPerformed(ActionEvent e) {
                 modifyTable(v -> v > 1 ? v : (byte) (1 - v));
             }
         }.setToolTip(Lang.get("menu_table_invert_tt")).createJMenuItem());
-        return setMenu;
     }
 
     private void modifyTable(BoolTableByteArray.TableModifier m) {
-        setModel(new TruthTableTableModel(model.getTable().modifyValues(m)));
+        try {
+            undoManager.apply(truthTable -> truthTable.modifyValues(m));
+            tableChanged();
+        } catch (ModifyException e) {
+            e.printStackTrace();
+            new ErrorMessage().addCause(e).show(TableDialog.this);
+        }
     }
 
     private JMenu createCreateMenu() {
@@ -527,8 +608,8 @@ public class TableDialog extends JDialog {
 
     private void createCircuit(boolean useJKff, boolean useLUTs, ExpressionModifier... modifier) {
         try {
-            final ModelAnalyserInfo modelAnalyzerInfo = model.getTable().getModelAnalyzerInfo();
-            CircuitBuilder circuitBuilder = new CircuitBuilder(shapeFactory, model.getTable().getVars())
+            final ModelAnalyserInfo modelAnalyzerInfo = undoManager.getActual().getModelAnalyzerInfo();
+            CircuitBuilder circuitBuilder = new CircuitBuilder(shapeFactory, undoManager.getActual().getVars())
                     .setUseJK(useJKff)
                     .setUseLUTs(useLUTs)
                     .setModelAnalyzerInfo(modelAnalyzerInfo);
@@ -555,19 +636,6 @@ public class TableDialog extends JDialog {
         return model;
     }
 
-    /**
-     * Sets the table model
-     *
-     * @param model the model to use
-     */
-    public void setModel(TruthTableTableModel model) {
-        this.model = model;
-        model.addTableModelListener(new CalculationTableModelListener());
-        table.setModel(model);
-        karnaughMenuAction.setEnabled(model.getTable().getVars().size() <= 4);
-        calculateExpressions();
-    }
-
     private String getProjectName() {
         if (filename == null)
             return "unknown";
@@ -598,6 +666,13 @@ public class TableDialog extends JDialog {
         }
     }
 
+    /**
+     * @return the undoManager
+     */
+    public UndoManager<TruthTable> getUndoManager() {
+        return undoManager;
+    }
+
     private class CalculationTableModelListener implements TableModelListener {
         @Override
         public void tableChanged(TableModelEvent tableModelEvent) {
@@ -613,7 +688,7 @@ public class TableDialog extends JDialog {
             if (createJK.isSelected())
                 expressionListener = new ExpressionListenerJK(expressionListener);
 
-            final TruthTable table = model.getTable();
+            final TruthTable table = undoManager.getActual();
             if (table.getVars().size() >= 8) {
                 ProgressDialog progress = new ProgressDialog(this);
 
@@ -674,7 +749,8 @@ public class TableDialog extends JDialog {
 
         @Override
         public void actionPerformed(ActionEvent actionEvent) {
-            setModel(new TruthTableTableModel(new TruthTable(n).addResult()));
+            undoManager.setInitial(new TruthTable(n).addResult());
+            tableChanged();
         }
     }
 
@@ -702,7 +778,8 @@ public class TableDialog extends JDialog {
                 i--;
             }
 
-            setModel(new TruthTableTableModel(truthTable));
+            undoManager.setInitial(truthTable);
+            tableChanged();
         }
     }
 
@@ -735,7 +812,8 @@ public class TableDialog extends JDialog {
                 i--;
             }
 
-            setModel(new TruthTableTableModel(truthTable));
+            undoManager.setInitial(truthTable);
+            tableChanged();
         }
     }
 
@@ -746,7 +824,7 @@ public class TableDialog extends JDialog {
             JLabel label = (JLabel) super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
             label.setHorizontalAlignment(SwingConstants.CENTER);
             label.setFont(font);
-            if (column < model.getTable().getVars().size())
+            if (column < undoManager.getActual().getVars().size())
                 label.setBackground(MYGRAY);
             else
                 label.setBackground(Color.WHITE);
@@ -761,7 +839,7 @@ public class TableDialog extends JDialog {
         }
     }
 
-    private final class StringDefaultTableCellRenderer extends DefaultTableCellRenderer {
+    private static final class StringDefaultTableCellRenderer extends DefaultTableCellRenderer {
         private StringDefaultTableCellRenderer() {
             setHorizontalAlignment(SwingConstants.CENTER);
         }
@@ -832,13 +910,13 @@ public class TableDialog extends JDialog {
             int c = table.getSelectedColumn();
             if (r < 0 || c < 0) {
                 r = 0;
-                c = model.getTable().getVars().size();
+                c = undoManager.getActual().getVars().size();
             }
             model.setValueAt(value, r, c);
 
             c++;
             if (c >= table.getColumnCount()) {
-                c = model.getTable().getVars().size();
+                c = undoManager.getActual().getVars().size();
                 r++;
                 if (r >= model.getRowCount())
                     r = 0;
@@ -859,7 +937,7 @@ public class TableDialog extends JDialog {
         @Override
         public void actionPerformed(ActionEvent e) {
             try {
-                generator.generate(TableDialog.this, filename, model.getTable(), lastGeneratedExpressions);
+                generator.generate(TableDialog.this, filename, undoManager.getActual(), lastGeneratedExpressions);
                 setLastUsedGenerator(generator);
             } catch (Exception e1) {
                 new ErrorMessage(Lang.get("msg_errorDuringHardwareExport")).addCause(e1).show(TableDialog.this);
diff --git a/src/main/java/de/neemann/digital/gui/components/table/TableReorderManager.java b/src/main/java/de/neemann/digital/gui/components/table/TableReorderManager.java
index 18c1b4d26..a5dda9198 100644
--- a/src/main/java/de/neemann/digital/gui/components/table/TableReorderManager.java
+++ b/src/main/java/de/neemann/digital/gui/components/table/TableReorderManager.java
@@ -10,6 +10,7 @@ import de.neemann.digital.analyse.TruthTableTableModel;
 import de.neemann.digital.analyse.expression.ExpressionException;
 import de.neemann.digital.analyse.expression.Variable;
 import de.neemann.digital.analyse.quinemc.BoolTable;
+import de.neemann.digital.undo.ModifyException;
 
 import javax.swing.*;
 import javax.swing.table.TableModel;
@@ -20,7 +21,7 @@ import java.util.ArrayList;
 /**
  * Handles reordering of the table columns by mouse drag and drop
  */
-public class TableReorderManager {
+class TableReorderManager {
 
     private final TableDialog tableDialog;
     private final JTable table;
@@ -31,7 +32,7 @@ public class TableReorderManager {
      * @param tableDialog the TableDialog instance
      * @param table       the table which is reordered
      */
-    public TableReorderManager(TableDialog tableDialog, JTable table) {
+    TableReorderManager(TableDialog tableDialog, JTable table) {
         this.tableDialog = tableDialog;
         this.table = table;
         table.getTableHeader().addMouseListener(new MouseAdapter() {
@@ -64,24 +65,32 @@ public class TableReorderManager {
         }
 
         if (wasChange) {
-            if (isVarChange(varList, vars)) {
-                try {
-                    TruthTable tt = new ReorderInputs(model.getTable(), vars).reorder();
-                    tableDialog.setModel(new TruthTableTableModel(tt));
-                } catch (ExpressionException e) {
-                    // can't happen because no columns are removed
-                    e.printStackTrace();
-                }
-            } else if (isResultChange(model.getTable(), results)) {
-                try {
-                    TruthTable tt = new ReorderOutputs(model.getTable(), results).reorder();
-                    tableDialog.setModel(new TruthTableTableModel(tt));
-                } catch (ExpressionException e) {
-                    // can't happen because no columns are removed
-                    e.printStackTrace();
-                }
-            } else
-                tableDialog.setModel(new TruthTableTableModel(model.getTable()));
+            try {
+                if (isVarChange(varList, vars)) {
+                    tableDialog.getUndoManager().apply(tt -> {
+                        try {
+                            new ReorderInputs(tt, vars).reorder();
+                        } catch (ExpressionException e) {
+                            // can't happen because no columns are removed
+                            e.printStackTrace();
+                        }
+                    });
+                    tableDialog.tableChanged();
+                } else if (isResultChange(model.getTable(), results)) {
+                    tableDialog.getUndoManager().apply(tt -> {
+                        try {
+                            new ReorderOutputs(tt, results).reorder();
+                        } catch (ExpressionException e) {
+                            // can't happen because no columns are removed
+                            e.printStackTrace();
+                        }
+                    });
+                    tableDialog.tableChanged();
+                } else
+                    tableDialog.tableChanged();
+            } catch (ModifyException e) {
+                e.printStackTrace();
+            }
         }
     }
 
diff --git a/src/main/resources/lang/lang_de.xml b/src/main/resources/lang/lang_de.xml
index 61f12aff5..7cdafb23f 100644
--- a/src/main/resources/lang/lang_de.xml
+++ b/src/main/resources/lang/lang_de.xml
@@ -1546,14 +1546,12 @@ Sind evtl. die Namen der Variablen nicht eindeutig?</string>
     <string name="menu_table_new_combinatorial">Kombinatorisch</string>
     <string name="menu_table_new_sequential">Automat</string>
     <string name="menu_table_new_sequential_bidir">Automat bidirektional</string>
-    <string name="menu_table_columns">Spalten</string>
     <string name="menu_table_reorder_inputs">Eingangsvariablen umsortieren/löschen</string>
     <string name="menu_table_reorder_outputs">Ergebnisspalten umsortieren/löschen</string>
     <string name="menu_table_columnsAdd">Ergebnisspalte hinzufügen</string>
     <string name="menu_table_columnsAdd_tt">Fügt der Tabelle eine Ergebnisspalte hinzu.</string>
     <string name="menu_table_columnsAddVariable">Eingangsvariable hinzufügen</string>
     <string name="menu_table_columnsAddVariable_tt">Fügt der Tabelle eine Variablenspalte hinzu.</string>
-    <string name="menu_table_set">Setzen</string>
     <string name="menu_table_setXTo0">Setze X auf 0</string>
     <string name="menu_table_setXTo0_tt">Setzt die Don't Cares auf 0.</string>
     <string name="menu_table_setXTo1">Setze X auf 1</string>
diff --git a/src/main/resources/lang/lang_en.xml b/src/main/resources/lang/lang_en.xml
index 786738aae..641eabc14 100644
--- a/src/main/resources/lang/lang_en.xml
+++ b/src/main/resources/lang/lang_en.xml
@@ -1529,14 +1529,12 @@
     <string name="menu_table_new_combinatorial">Combinatorial</string>
     <string name="menu_table_new_sequential">Sequential</string>
     <string name="menu_table_new_sequential_bidir">Sequential bidirectional</string>
-    <string name="menu_table_columns">Columns</string>
     <string name="menu_table_reorder_inputs">Reorder/Delete Input Variables</string>
     <string name="menu_table_columnsAddVariable">Add Input Variable</string>
     <string name="menu_table_columnsAddVariable_tt">Adds a new input variable to the table.</string>
     <string name="menu_table_reorder_outputs">Reorder/Delete Output Columns</string>
     <string name="menu_table_columnsAdd">Add Output Column</string>
     <string name="menu_table_columnsAdd_tt">Adds a new result column to the table.</string>
-    <string name="menu_table_set">Set</string>
     <string name="menu_table_setXTo0">Set X to 0</string>
     <string name="menu_table_setXTo0_tt">Sets the Don't Cares to 0.</string>
     <string name="menu_table_setXTo1">Set X to 1</string>
diff --git a/src/main/resources/lang/lang_es.xml b/src/main/resources/lang/lang_es.xml
index 1efeb74ea..2efe3dda6 100644
--- a/src/main/resources/lang/lang_es.xml
+++ b/src/main/resources/lang/lang_es.xml
@@ -1293,14 +1293,12 @@
   <string name="menu_table_new_combinatorial">Combinacional</string>
   <string name="menu_table_new_sequential">Secuencial</string>
   <string name="menu_table_new_sequential_bidir">Secuencial bidireccional</string>
-  <string name="menu_table_columns">Columnas</string>
   <string name="menu_table_reorder_inputs">Reordena/Borra variables de entrada</string>
   <string name="menu_table_reorder_outputs">Reordena/Borra columnas de salida</string>
   <string name="menu_table_columnsAdd">Añade columna de salida</string>
   <string name="menu_table_columnsAdd_tt">Añade una nueva columna de resultado a la tabla.</string>
   <string name="menu_table_columnsAddVariable">Añade variable de entrada</string>
   <string name="menu_table_columnsAddVariable_tt">Añade una nueva variable de entrada a la tabla.</string>
-  <string name="menu_table_set">Fijar</string>
   <string name="menu_table_setXTo0">Fijar X a 0</string>
   <string name="menu_table_setXTo0_tt">Convierte los "indiferentes" a 0.</string>
   <string name="menu_table_setXTo1">Poner X a 1</string>
diff --git a/src/main/resources/lang/lang_es_ref.xml b/src/main/resources/lang/lang_es_ref.xml
index bb485ee62..c825aa2b4 100644
--- a/src/main/resources/lang/lang_es_ref.xml
+++ b/src/main/resources/lang/lang_es_ref.xml
@@ -1306,14 +1306,12 @@
   <string name="menu_table_new_combinatorial">Combinatorial</string>
   <string name="menu_table_new_sequential">Sequential</string>
   <string name="menu_table_new_sequential_bidir">Sequential bidirectional</string>
-  <string name="menu_table_columns">Columns</string>
   <string name="menu_table_reorder_inputs">Reorder/Delete Input Variables</string>
   <string name="menu_table_reorder_outputs">Reorder/Delete Output Columns</string>
   <string name="menu_table_columnsAdd">Add Output Column</string>
   <string name="menu_table_columnsAdd_tt">Adds a new result column to the table.</string>
   <string name="menu_table_columnsAddVariable">Add Input Variable</string>
   <string name="menu_table_columnsAddVariable_tt">Adds a new input variable to the table.</string>
-  <string name="menu_table_set">Set</string>
   <string name="menu_table_setXTo0">Set X to 0</string>
   <string name="menu_table_setXTo0_tt">Sets the Don't Cares to 0.</string>
   <string name="menu_table_setXTo1">Set X to 1</string>
diff --git a/src/main/resources/lang/lang_pt.xml b/src/main/resources/lang/lang_pt.xml
index 65f3725d8..6dbb6e475 100644
--- a/src/main/resources/lang/lang_pt.xml
+++ b/src/main/resources/lang/lang_pt.xml
@@ -1362,14 +1362,12 @@
   <string name="menu_table_new_combinatorial">Combinacional</string>
   <string name="menu_table_new_sequential">Sequencial</string>
   <string name="menu_table_new_sequential_bidir">Sequencial bidirecional</string>
-  <string name="menu_table_columns">Colunas</string>
   <string name="menu_table_reorder_inputs">Reordenar/remover variáveis de entrada</string>
   <string name="menu_table_columnsAddVariable">Adicionar variável de entrada</string>
   <string name="menu_table_columnsAddVariable_tt">Adicionar uma nova variável de entrada à tabela.</string>
   <string name="menu_table_reorder_outputs">Reordenar/remover colunas de saída</string>
   <string name="menu_table_columnsAdd">Adicionar coluna de saída</string>
   <string name="menu_table_columnsAdd_tt">Adicionar uma nova coluna de resultado à tabela.</string>
-  <string name="menu_table_set">Definir</string>
   <string name="menu_table_setXTo0">Definir X como 0</string>
   <string name="menu_table_setXTo0_tt">Definir "don't cares" como 0.</string>
   <string name="menu_table_setXTo1">Definir X como 1</string>
diff --git a/src/main/resources/lang/lang_pt_ref.xml b/src/main/resources/lang/lang_pt_ref.xml
index fc8eccb24..df378a19f 100644
--- a/src/main/resources/lang/lang_pt_ref.xml
+++ b/src/main/resources/lang/lang_pt_ref.xml
@@ -1373,14 +1373,12 @@
   <string name="menu_table_new_combinatorial">Combinatorial</string>
   <string name="menu_table_new_sequential">Sequential</string>
   <string name="menu_table_new_sequential_bidir">Sequential bidirectional</string>
-  <string name="menu_table_columns">Columns</string>
   <string name="menu_table_reorder_inputs">Reorder/Delete Input Variables</string>
   <string name="menu_table_columnsAddVariable">Add Input Variable</string>
   <string name="menu_table_columnsAddVariable_tt">Adds a new input variable to the table.</string>
   <string name="menu_table_reorder_outputs">Reorder/Delete Output Columns</string>
   <string name="menu_table_columnsAdd">Add Output Column</string>
   <string name="menu_table_columnsAdd_tt">Adds a new result column to the table.</string>
-  <string name="menu_table_set">Set</string>
   <string name="menu_table_setXTo0">Set X to 0</string>
   <string name="menu_table_setXTo0_tt">Sets the Don't Cares to 0.</string>
   <string name="menu_table_setXTo1">Set X to 1</string>
diff --git a/src/test/java/de/neemann/digital/docu/ScreenShots.java b/src/test/java/de/neemann/digital/docu/ScreenShots.java
index 21fa9a3b4..14438be4c 100644
--- a/src/test/java/de/neemann/digital/docu/ScreenShots.java
+++ b/src/test/java/de/neemann/digital/docu/ScreenShots.java
@@ -159,6 +159,7 @@ public class ScreenShots {
                 .add(new GuiTester.CloseTopMost())
                 .execute();
 
+        /*
         File trafficLight = new File(Resources.getRoot(), "../../main/fsm/trafficLightBlink.fsm");
         new GuiTester()
                 .press("F10")
@@ -217,7 +218,7 @@ public class ScreenShots {
                 .add(new GuiTester.CloseTopMost())
                 .add(new GuiTester.CloseTopMost())
                 .add(new GuiTester.CloseTopMost())
-                .execute();/**/
+                .execute();*/
     }
 
     private static GuiTester.WindowCheck<Window> closeAllSolutionsDialog() {
diff --git a/src/test/java/de/neemann/digital/gui/components/table/LaTeXExpressionListenerTest.java b/src/test/java/de/neemann/digital/gui/components/table/LaTeXExpressionListenerTest.java
index b7611eab9..478c2d76a 100644
--- a/src/test/java/de/neemann/digital/gui/components/table/LaTeXExpressionListenerTest.java
+++ b/src/test/java/de/neemann/digital/gui/components/table/LaTeXExpressionListenerTest.java
@@ -21,8 +21,7 @@ public class LaTeXExpressionListenerTest extends TestCase {
                 .addVariable("A")
                 .addVariable("B")
                 .addResult("Y", new BoolTableBoolArray(new boolean[]{false, false, true, false}));
-        TruthTableTableModel model = new TruthTableTableModel(tt);
-        LaTeXExpressionListener l = new LaTeXExpressionListener(model);
+        LaTeXExpressionListener l = new LaTeXExpressionListener(tt);
         l.resultFound("Y", Operation.and(new Variable("A"), new Not(new Variable("B"))));
         l.close();
 
diff --git a/src/test/java/de/neemann/digital/gui/components/table/TestReorderInputs.java b/src/test/java/de/neemann/digital/gui/components/table/TestReorderInputs.java
index 5c623756d..50c1f9f30 100644
--- a/src/test/java/de/neemann/digital/gui/components/table/TestReorderInputs.java
+++ b/src/test/java/de/neemann/digital/gui/components/table/TestReorderInputs.java
@@ -21,9 +21,10 @@ public class TestReorderInputs extends TestCase {
             col.set(i, i + 1);
 
 
-        ReorderInputs reorderInputs = new ReorderInputs(t);
+        TruthTable newTable = t.createDeepCopy();
+        ReorderInputs reorderInputs = new ReorderInputs(newTable);
         reorderInputs.getItems().swap(1, 2);
-        TruthTable newTable = reorderInputs.reorder();
+        reorderInputs.reorder();
 
 
         ContextFiller cf = new ContextFiller(t.getVars());
@@ -39,9 +40,10 @@ public class TestReorderInputs extends TestCase {
         for (int i = 0; i < t.getRows(); i++)
             col.set(i, i + 1);
 
-        ReorderInputs reorderInputs = new ReorderInputs(t);
+        TruthTable newTable = t.createDeepCopy();
+        ReorderInputs reorderInputs = new ReorderInputs(newTable);
         reorderInputs.getItems().delete(2);
-        TruthTable newTable = reorderInputs.reorder();
+        reorderInputs.reorder();
 
         assertEquals(2, newTable.getVars().size());
         assertEquals(1, newTable.getResultCount());
diff --git a/src/test/java/de/neemann/digital/gui/components/table/TestReorderOutputs.java b/src/test/java/de/neemann/digital/gui/components/table/TestReorderOutputs.java
index bbaac7059..56f3c2a14 100644
--- a/src/test/java/de/neemann/digital/gui/components/table/TestReorderOutputs.java
+++ b/src/test/java/de/neemann/digital/gui/components/table/TestReorderOutputs.java
@@ -19,9 +19,10 @@ public class TestReorderOutputs extends TestCase {
         for (int i = 0; i < t.getRows(); i++)
             col.set(i, i + 1);
 
-        ReorderOutputs reorderOutputs = new ReorderOutputs(t);
+        TruthTable newTable = t.createDeepCopy();
+        ReorderOutputs reorderOutputs = new ReorderOutputs(newTable);
         reorderOutputs.getItems().delete(1);
-        TruthTable newTable = reorderOutputs.reorder();
+        reorderOutputs.reorder();
 
         assertEquals(3, newTable.getVars().size());
         assertEquals(1, newTable.getResultCount());