diff --git a/Source/CustomSynth.cpp b/Source/CustomSynth.cpp
index ed1bf4d..ab295b8 100644
--- a/Source/CustomSynth.cpp
+++ b/Source/CustomSynth.cpp
@@ -10,32 +10,107 @@
 
 #include "CustomSynth.h"
 #include "BaseVoice.h"
+#include "TonalVoice.h"
 #include "PluginProcessor.h"
 
 CustomSynth::CustomSynth(Magical8bitPlug2AudioProcessor& p) : processor(p) {}
 
-void CustomSynth::noteOn(int midiChannel, int midiNoteNumber, float velocity) {
-    // Poly
+TonalVoice* CustomSynth::getVoiceIfShouldProcessInMonoMode() {
     if (!processor.settingRefs.isMonophonic()) {
+        return nullptr;
+    }
+    if (processor.settingRefs.monophonicBehavior() == kNonLegato) {
+        return nullptr;
+    }
+    
+    // Try casting into TonalVoice* and return it if success(otherwise returns nullptr)
+    return dynamic_cast<TonalVoice *>(voices.getFirst());
+}
+
+void CustomSynth::noteOn(int midiChannel, int midiNoteNumber, float velocity) {
+    TonalVoice *voice = getVoiceIfShouldProcessInMonoMode();
+    
+    if (voice == nullptr) {
         Synthesiser::noteOn(midiChannel, midiNoteNumber, velocity);
         return;
     }
     
     // Mono
-    auto voice = voices.getFirst();
     
-    if (voice == nullptr) {
-        return;
-    }
+    // Start thread guard
+    const ScopedLock sl (lock);
+
     if (voice->isKeyDown()) {
-        ((BaseVoice*)voice)->changeNote(midiNoteNumber, velocity);
+        // Already key on
+        switch (processor.settingRefs.monophonicBehavior()) {
+            case kLegato:
+                voice->addLegatoNote(midiNoteNumber, velocity);
+                break;
+            case kArpeggioUp:
+                voice->addArpeggioNoteAscending(midiNoteNumber);
+                break;
+            case kArpeggioDown:
+                voice->addArpeggioNoteDescending(midiNoteNumber);
+                break;
+            default:
+                // no-op
+                break;
+        }
     } else {
-        Synthesiser::noteOn(midiChannel, midiNoteNumber, velocity);
+        switch (processor.settingRefs.monophonicBehavior()) {
+            case kLegato:
+                // just start
+                Synthesiser::noteOn(midiChannel, midiNoteNumber, velocity);
+                voice->setLegatoMode(*(processor.settingRefs.portamentoTime));
+                break;
+            case kArpeggioUp:
+            case kArpeggioDown:
+                // calc arpeggio interval
+                // set arpeggio mode with this note number and arp interval
+                break;
+            default:
+                // no-op
+                break;
+        }
     }
 }
 
 void CustomSynth::noteOff(int midiChannel, int midiNoteNumber, float velocity, bool allowTailOff) {
-    Synthesiser::noteOff(midiChannel, midiNoteNumber, velocity, allowTailOff);
+    TonalVoice *voice = getVoiceIfShouldProcessInMonoMode();
+    
+    if (voice == nullptr) {
+        Synthesiser::noteOff(midiChannel, midiNoteNumber, velocity, allowTailOff);
+        return;
+    }
+    
+    // mono
+    
+    // Start thread guard
+    const ScopedLock sl (lock);
+
+    if (!voice->isKeyDown()) {
+        // key is already off
+        return;
+    }
+    
+    switch (processor.settingRefs.monophonicBehavior()) {
+        case kLegato:
+        {
+            int numBuffer = voice->removeLegatoNote(midiNoteNumber);
+            if (numBuffer < 1) {
+                Synthesiser::noteOff(midiChannel, voice->getCurrentlyPlayingNote(), velocity, allowTailOff);
+            }
+        }
+            break;
+        case kArpeggioUp:
+        case kArpeggioDown:
+            // remove arpeggio note and get # of remaining arpeggio notes
+            // if zero
+            //   all notes off
+            break;
+        default:
+            break;
+    }
 }
 
 void CustomSynth::allNotesOff (const int midiChannel, const bool allowTailOff) {
diff --git a/Source/CustomSynth.h b/Source/CustomSynth.h
index a839784..51dfa18 100644
--- a/Source/CustomSynth.h
+++ b/Source/CustomSynth.h
@@ -12,6 +12,7 @@
 #include "../JuceLibraryCode/JuceHeader.h"
 
 class Magical8bitPlug2AudioProcessor;
+class TonalVoice;
 
 class CustomSynth : public Synthesiser {
 public:
@@ -22,5 +23,6 @@ public:
     void allNotesOff (const int midiChannel, const bool allowTailOff) override;
     
 private:
+    TonalVoice* getVoiceIfShouldProcessInMonoMode();
     Magical8bitPlug2AudioProcessor& processor;
 };
diff --git a/Source/TonalVoice.cpp b/Source/TonalVoice.cpp
index f0471bc..62cd1fa 100644
--- a/Source/TonalVoice.cpp
+++ b/Source/TonalVoice.cpp
@@ -16,7 +16,9 @@
 // The base for pulse/triangle (Abstract)
 //
 //---------------------------------------------
-TonalVoice::TonalVoice (SettingRefs* sRefs) : BaseVoice (sRefs) {}
+TonalVoice::TonalVoice (SettingRefs* sRefs) : BaseVoice (sRefs) {
+    // testArpeggioNotes();
+}
 
 void TonalVoice::startNote (int midiNoteNumber, float velocity, SynthesiserSound*, int currentPitchBendPosition)
 {
@@ -30,6 +32,12 @@ void TonalVoice::startNote (int midiNoteNumber, float velocity, SynthesiserSound
     float time = * (settingRefs->sweepTime);
     currentAutoBendAmount = iniPitch;
     autoBendDelta = -1.0 * iniPitch / (time * getSampleRate());
+    
+    portamentoTime = 0;
+    currentArpeggioFrame = 0;
+    arpeggioFrameTimer = 0;
+    arpeggioFrameLength = 0;
+    currentNumNoteBuffer = 0;
 }
 
 void TonalVoice::advanceControlFrame()
@@ -90,6 +98,127 @@ void TonalVoice::controllerMoved (int type, int amount)
     }
 }
 
+
+void TonalVoice::setLegatoMode(double time) {
+    portamentoTime = time;
+//    currentNumNoteBuffer = 1;
+//    noteBuffer[0] = noteNumber;
+}
+
+void TonalVoice::addLegatoNote (int midiNoteNumber, float velocity) {
+    if (currentNumNoteBuffer >= 10) {
+        return;
+    }
+
+    // Push to last
+//    noteBuffer[currentNumNoteBuffer] = midiNoteNumber;
+//    currentNumNoteBuffer++;
+    
+    int previousNoteNo = noteNumber;
+    BaseVoice::changeNote(midiNoteNumber, velocity);
+    
+    // Portamento implementation is just applying auto bend
+    if (portamentoTime > 0) {
+        currentAutoBendAmount = (double)(previousNoteNo - midiNoteNumber);
+        autoBendDelta = -1.0 * currentAutoBendAmount / (portamentoTime * getSampleRate());
+    }
+}
+
+int TonalVoice::removeLegatoNote(int midiNoteNumber) {
+//    if (currentNumNoteBuffer==0) {
+//        return 0;
+//    }
+//
+//    int i;
+//    for (i=0; i<currentNumNoteBuffer; i++) {
+//        if (noteBuffer[i] == midiNoteNumber) break;
+//    }
+//    if (i == currentNumNoteBuffer) { // not found
+//        return currentNumNoteBuffer;
+//    }
+//    shiftNoteBuffer(i);
+//    currentNumNoteBuffer--;
+    
+    if (midiNoteNumber == noteNumber) {
+        return 0;
+    } else {
+        return 1;
+    }
+}
+
+
+void TonalVoice::setArpeggioMode(double interval)
+{
+    arpeggioFrameLength = interval;
+    arpeggioFrameTimer = 0;
+    currentArpeggioFrame = 0;
+    currentNumNoteBuffer = 1;
+    noteBuffer[0] = noteNumber;
+}
+
+void TonalVoice::addArpeggioNoteAscending(int midiNoteNumber)
+{
+    if (currentNumNoteBuffer >= 10) {
+        return;
+    }
+    int i;
+    for (i = 0; i<currentNumNoteBuffer; i++) {
+        if (noteBuffer[i] > midiNoteNumber) break;
+    }
+    
+    pushNoteBuffer(i, midiNoteNumber);
+    
+    currentNumNoteBuffer++;
+}
+
+void TonalVoice::addArpeggioNoteDescending(int midiNoteNumber)
+{
+    if (currentNumNoteBuffer >= 10) {
+        return;
+    }
+    int i;
+    for (i = 0; i<currentNumNoteBuffer; i++) {
+        if (noteBuffer[i] < midiNoteNumber) break;
+    }
+    
+    pushNoteBuffer(i, midiNoteNumber);
+    
+    currentNumNoteBuffer++;
+}
+
+/// Returns number of remaining arpeggio notes
+int TonalVoice::removeArpeggioNote(int midiNoteNumber)
+{
+    if (currentNumNoteBuffer==0) {
+        return 0;
+    }
+    
+    int i;
+    for (i=0; i<currentNumNoteBuffer; i++) {
+        if (noteBuffer[i] == midiNoteNumber) break;
+    }
+    if (i == currentNumNoteBuffer) { // not found
+        return currentNumNoteBuffer;
+    }
+    shiftNoteBuffer(i);
+    currentNumNoteBuffer--;
+    
+    return currentNumNoteBuffer;
+}
+
+void TonalVoice::pushNoteBuffer(int index, int value) {
+    for (int i=9; i>index; i--) {
+        noteBuffer[i] = noteBuffer[i-1];
+    }
+    noteBuffer[index] = value;
+}
+
+void TonalVoice::shiftNoteBuffer(int index) {
+    for (int i=index; i<9; i++) {
+        noteBuffer[i] = noteBuffer[i+1];
+    }
+}
+
 double TonalVoice::noteNoToHeltzDouble (double noteNoInDouble, const double frequencyOfA)
 {
     return frequencyOfA * std::pow (2.0, (noteNoInDouble - 69) / 12.0);
diff --git a/Source/TonalVoice.h b/Source/TonalVoice.h
index 5146fb7..2acb0c0 100644
--- a/Source/TonalVoice.h
+++ b/Source/TonalVoice.h
@@ -13,7 +13,6 @@
 
 struct TonalVoice : public BaseVoice   // The base for Pulse and Triangle
 {
-
     TonalVoice (SettingRefs* sRefs);
     float voltageForAngle (double angle) override = 0;
 
@@ -35,6 +34,18 @@ struct TonalVoice : public BaseVoice   // The base for Pulse and Triangle
 
     // Custom Pitch/Note states
     int currentPitchSequenceFrame = 0;
+    
+    // Legato/Arpeggio
+    int noteBuffer[10];
+    int currentNumNoteBuffer = 0;
+
+    // Legato
+    double portamentoTime = 0;
+
+    // Arpeggio
+    int currentArpeggioFrame = 0;
+    double arpeggioFrameTimer = 0;
+    double arpeggioFrameLength = 0; // Unit: seconds. Set non-zero value to enable arpeggio
 
     void startNote (int midiNoteNumber, float velocity,
                     SynthesiserSound*, int currentPitchWheelPosition) override;
@@ -43,7 +54,92 @@ struct TonalVoice : public BaseVoice   // The base for Pulse and Triangle
     void pitchWheelMoved (int) override;
     void controllerMoved (int, int) override;
 
+    void setLegatoMode(double time);
+    void addLegatoNote (int midiNoteNumber, float velocity);
+    int removeLegatoNote(int midiNoteNumber);
+
+    void setArpeggioMode(double interval);
+    void addArpeggioNoteAscending(int midiNoteNumber);
+    void addArpeggioNoteDescending(int midiNoteNumber);
+    int removeArpeggioNote(int midiNoteNumber);
+    
+    void pushNoteBuffer(int index, int value);
+    void shiftNoteBuffer(int index);
+
     double noteNoToHeltzDouble (double noteNoInDouble, const double frequencyOfA = 440);
 
     void onFrameAdvanced() override;
+    
+    bool isArpeggioEnabled() {
+        return arpeggioFrameLength > 0;
+    }
+    
+    /*
+    void testArpeggioNotes() {
+        startNote(100, 1, NULL, 0);
+        
+        setArpeggioMode(1.0);
+        jassert(isArpeggioEnabled());
+        jassert(arpeggioNotes[0] == 100);
+        jassert(currentNumArpeggioNotes == 1);
+        
+        addArpeggioNoteAscending(90);
+        jassert(arpeggioNotes[0] == 90);
+        jassert(arpeggioNotes[1] == 100);
+        jassert(currentNumArpeggioNotes == 2);
+        
+        addArpeggioNoteAscending(95);
+        jassert(arpeggioNotes[0] == 90);
+        jassert(arpeggioNotes[1] == 95);
+        jassert(arpeggioNotes[2] == 100);
+        jassert(currentNumArpeggioNotes == 3);
+
+        jassert(removeArpeggioNote(92) == 3);
+        jassert(arpeggioNotes[0] == 90);
+        jassert(arpeggioNotes[1] == 95);
+        jassert(arpeggioNotes[2] == 100);
+
+        jassert(removeArpeggioNote(100) == 2);
+        jassert(arpeggioNotes[0] == 90);
+        jassert(arpeggioNotes[1] == 95);
+
+        jassert(removeArpeggioNote(90) == 1);
+        jassert(arpeggioNotes[0] == 95);
+
+        jassert(removeArpeggioNote(95) == 0);
+        
+        
+        startNote(100, 1, NULL, 0);
+        
+        setArpeggioMode(1.0);
+        jassert(isArpeggioEnabled());
+        jassert(arpeggioNotes[0] == 100);
+        jassert(currentNumArpeggioNotes == 1);
+        
+        addArpeggioNoteDescending(90);
+        jassert(arpeggioNotes[0] == 100);
+        jassert(arpeggioNotes[1] == 90);
+        jassert(currentNumArpeggioNotes == 2);
+        
+        addArpeggioNoteDescending(95);
+        jassert(arpeggioNotes[0] == 100);
+        jassert(arpeggioNotes[1] == 95);
+        jassert(arpeggioNotes[2] == 90);
+        jassert(currentNumArpeggioNotes == 3);
+
+        jassert(removeArpeggioNote(92) == 3);
+        jassert(arpeggioNotes[0] == 100);
+        jassert(arpeggioNotes[1] == 95);
+        jassert(arpeggioNotes[2] == 90);
+
+        jassert(removeArpeggioNote(100) == 2);
+        jassert(arpeggioNotes[0] == 95);
+        jassert(arpeggioNotes[1] == 90);
+
+        jassert(removeArpeggioNote(90) == 1);
+        jassert(arpeggioNotes[0] == 95);
+
+        jassert(removeArpeggioNote(95) == 0);
+    }
+     */
 };