diff --git a/BallanceTASEditor.csproj b/BallanceTASEditor.csproj
index 1e57390..0c888ac 100644
--- a/BallanceTASEditor.csproj
+++ b/BallanceTASEditor.csproj
@@ -60,6 +60,7 @@
     <Compile Include="Core\ClipboardUtil.cs" />
     <Compile Include="Core\FileOperation.cs" />
     <Compile Include="Core\KeyboardState.cs" />
+    <Compile Include="Core\LimitedStack.cs" />
     <Compile Include="UI\AddItem.xaml.cs">
       <DependentUpon>AddItem.xaml</DependentUpon>
     </Compile>
diff --git a/Core/FileOperation.cs b/Core/FileOperation.cs
index eda25f8..861ca6a 100644
--- a/Core/FileOperation.cs
+++ b/Core/FileOperation.cs
@@ -325,14 +325,26 @@ namespace BallanceTASEditor.Core.FileOperation {
                         long counter = 0;
                         if (isInsertBefore) {
                             foreach (var item in data.IterateFull()) {
-                                mMem.AddBefore(node, item.Value);
+                                if (node == null) {
+                                    // insert from tail instead
+                                    mMem.AddLast(item.Value);
+                                } else {
+                                    mMem.AddBefore(node, item.Value);
+                                }
+                                
                                 if (counter == gottenPointerPos)
                                     mPointer = node.Previous;
                                 counter++;
                             }
                         } else {
                             foreach (var item in data.IterateFullReversed()) {
-                                mMem.AddAfter(node, item.Value);
+                                if (node == null) {
+                                    // insert from head instead
+                                    mMem.AddFirst(item.Value);
+                                } else {
+                                    mMem.AddAfter(node, item.Value);
+                                }
+                                
                                 if (counter == gottenPointerPos)
                                     mPointer = node.Next;
                                 counter++;
diff --git a/Core/LimitedStack.cs b/Core/LimitedStack.cs
new file mode 100644
index 0000000..c894329
--- /dev/null
+++ b/Core/LimitedStack.cs
@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BallanceTASEditor.Core {
+    public class LimitedStack<T> {
+        private static readonly int STACK_LENGTH = 20;
+
+        public LimitedStack() {
+            _stack = new LinkedList<T>();
+        }
+
+        private LinkedList<T> _stack;
+
+        public void Push(T data) {
+            _stack.AddLast(data);
+            if (_stack.Count > STACK_LENGTH) {
+                _stack.RemoveFirst();
+            }
+        }
+
+        public T Pop() {
+            if (_stack.Last == null) return default(T);
+            var data = _stack.Last.Value;
+            _stack.RemoveLast();
+            return data;
+        }
+
+        public void Clear() {
+            _stack.Clear();
+        }
+
+        public bool IsEmpty() {
+            return _stack.Count == 0;
+        }
+        
+    }
+}
diff --git a/Core/TASFile.cs b/Core/TASFile.cs
index 5d11fcc..021e8e8 100644
--- a/Core/TASFile.cs
+++ b/Core/TASFile.cs
@@ -1,4 +1,5 @@
-using BallanceTASEditor.Core.TASStruct;
+using BallanceTASEditor.Core.FileOperation;
+using BallanceTASEditor.Core.TASStruct;
 using BallanceTASEditor.UI;
 using System;
 using System.Collections.Generic;
@@ -18,6 +19,9 @@ namespace BallanceTASEditor.Core {
             fs.Dispose();
             mPointer = mMem.First;
             mPointerIndex = 0;
+
+            mRedoStack = new LimitedStack<RevocableOperation>();
+            mUndoStack = new LimitedStack<RevocableOperation>();
         }
 
         public string mFilename { get; private set; }
@@ -26,6 +30,9 @@ namespace BallanceTASEditor.Core {
         LinkedListNode<FrameData> mPointer;
         long mPointerIndex;
 
+        LimitedStack<RevocableOperation> mRedoStack;
+        LimitedStack<RevocableOperation> mUndoStack;
+
         public bool IsEmpty() {
             return (mPointer == null);
         }
@@ -67,6 +74,11 @@ namespace BallanceTASEditor.Core {
 
         // if isSet is null, mean flip state
         public void Set(SelectionRange field, SelectionRange absoluteRange, bool? isSet) {
+            var oper = new SetOperation(field, absoluteRange, isSet);
+            oper.Do(ref mMem, ref mPointer, ref mPointerIndex);
+            mUndoStack.Push(oper);
+            mRedoStack.Clear();
+            /*
             if (mPointer == null) return;
 
             uint offset = 0;
@@ -78,9 +90,15 @@ namespace BallanceTASEditor.Core {
                 else if (isSet == true) item.Value.SetKeyStates(offset);
                 else if (isSet == false) item.Value.UnsetKeyStates(offset);
             }
+            */
         }
 
         public void Remove(SelectionRange absoluteRange) {
+            var oper = new RemoveOperation(absoluteRange);
+            oper.Do(ref mMem, ref mPointer, ref mPointerIndex);
+            mUndoStack.Push(oper);
+            mRedoStack.Clear();
+            /*
             if (mPointer == null) return;
 
             // remove
@@ -105,9 +123,15 @@ namespace BallanceTASEditor.Core {
                     mPointerIndex = newIndex;
                 }
             }
+            */
         }
 
         public void Add(long absolutePos, long count, float deltaTime, bool isAddBefore) {
+            var oper = new AddOperation(absolutePos, count, deltaTime, isAddBefore);
+            oper.Do(ref mMem, ref mPointer, ref mPointerIndex);
+            mUndoStack.Push(oper);
+            mRedoStack.Clear();
+            /*
             if (count <= 0) return;
 
             if (mPointer == null) {
@@ -132,9 +156,15 @@ namespace BallanceTASEditor.Core {
                     }
                 }
             }
+            */
         }
 
-        public void Insert(long absolutePos, LinkedList<FrameData> data, bool isInsertBefore) {
+        public void Insert(long absolutePos, LinkedList<FrameData> data, bool isInsertBefore, bool isOverwritten) {
+            var oper = new InsertOperation(absolutePos, data, isInsertBefore, isOverwritten);
+            oper.Do(ref mMem, ref mPointer, ref mPointerIndex);
+            mUndoStack.Push(oper);
+            mRedoStack.Clear();
+            /*
             if (data.Count == 0) return;
 
             // the same process route with add function
@@ -156,6 +186,21 @@ namespace BallanceTASEditor.Core {
                     }
                 }
             }
+            */
+        }
+
+        public void Redo() {
+            if (mRedoStack.IsEmpty()) return;
+            var oper = mRedoStack.Pop();
+            oper.Do(ref mMem, ref mPointer, ref mPointerIndex);
+            mUndoStack.Push(oper);
+        }
+
+        public void Undo() {
+            if (mUndoStack.IsEmpty()) return;
+            var oper = mUndoStack.Pop();
+            oper.Undo(ref mMem, ref mPointer, ref mPointerIndex);
+            mRedoStack.Push(oper);
         }
 
         public void Copy(SelectionRange absoluteRange, LinkedList<FrameData> data) {