diff --git a/main.cpp b/main.cpp
index 1ba332bb..1168560c 100644
--- a/main.cpp
+++ b/main.cpp
@@ -17,12 +17,35 @@
 #include "SleepLib/loader_plugins/zeo_loader.h"
 #include "SleepLib/loader_plugins/resmed_loader.h"
 
+MainWindow *mainwin;
+
+void MyOutputHandler(QtMsgType type, const char *msg) {
+    if (!mainwin) return;
+    switch (type) {
+        case QtDebugMsg:
+            mainwin->Log(msg);
+            break;
+        case QtWarningMsg:
+            mainwin->Log(QString("Warning: ")+msg);
+            break;
+        case QtFatalMsg:
+            mainwin->Log(QString("Fatal: ")+msg);
+            break;
+        case QtCriticalMsg:
+            mainwin->Log(QString("Critical: ")+msg);
+            break;
+            // Popup a messagebox
+            //abort();
+    }
+}
 
 int main(int argc, char *argv[])
 {
     QApplication a(argc, argv);
+    qInstallMsgHandler(MyOutputHandler);
 
     a.setApplicationName("SleepyHead");
+
     int id=QFontDatabase::addApplicationFont(":/fonts/FreeSans.ttf");
     QStringList ffam=QFontDatabase::applicationFontFamilies(id);
     for (QStringList::iterator i=ffam.begin();i!=ffam.end();i++) {
@@ -30,13 +53,14 @@ int main(int argc, char *argv[])
     }
 
     a.setFont(QFont("FreeSans",10));
+    MainWindow w;
+    mainwin=&w;
 
     PRS1Loader::Register();
     CMS50Loader::Register();
     ZEOLoader::Register();
     ResmedLoader::Register();
 
-    MainWindow w;
     w.show();
 
     return a.exec();
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 94a62202..3fa46310 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -20,6 +20,12 @@
 QProgressBar *qprogress;
 QLabel *qstatus;
 
+void MainWindow::Log(QString s)
+{
+    ui->logText->appendPlainText(s);
+}
+
+
 QString subversion="0";
 MainWindow::MainWindow(QWidget *parent) :
     QMainWindow(parent),
@@ -31,6 +37,7 @@ MainWindow::MainWindow(QWidget *parent) :
 #endif
     ui->setupUi(this);
     this->setWindowTitle(tr("SleepyHead")+QString(" v0.8.")+subversion);
+    ui->tabWidget->setCurrentIndex(0);
 
     QGLFormat fmt;
     fmt.setDepth(false);
@@ -60,6 +67,9 @@ MainWindow::MainWindow(QWidget *parent) :
     if (!pref.Exists("LinkGraphMovement")) pref["LinkGraphMovement"]=true;
     else ui->action_Link_Graphs->setChecked(pref["LinkGraphMovement"].toBool());
 
+    if (!pref.Exists("ShowDebug")) pref["ShowDebug"]=false;
+    else ui->actionDebug->setChecked(pref["ShowDebug"].toBool());
+
     if (!pref.Exists("NoonDateSplit")) pref["NoonDateSplit"]=false;
     else ui->action_Noon_Date_Split->setChecked(pref["NoonDateSplit"].toBool());
 
@@ -99,13 +109,13 @@ void MainWindow::Startup()
     profile->LoadMachineData();
 
     daily=new Daily(ui->tabWidget,shared_context);
-    ui->tabWidget->addTab(daily,tr("Daily"));
+    ui->tabWidget->insertTab(1,daily,tr("Daily"));
 
     overview=new Overview(ui->tabWidget,shared_context);
-    ui->tabWidget->addTab(overview,tr("Overview"));
+    ui->tabWidget->insertTab(2,overview,tr("Overview"));
 
     oximetry=new Oximetry(ui->tabWidget);
-    ui->tabWidget->addTab(oximetry,tr("Oximetry"));
+    ui->tabWidget->insertTab(3,oximetry,tr("Oximetry"));
 
     qprogress->hide();
     qstatus->setText(tr("Ready"));
@@ -257,3 +267,16 @@ void MainWindow::on_action_Noon_Date_Split_toggled(bool checked)
 {
     pref["NoonDateSplit"]=checked;
 }
+
+void MainWindow::on_actionDebug_toggled(bool checked)
+{
+    pref["ShowDebug"]=checked;
+    int idx=ui->tabWidget->indexOf(ui->debugTab);
+    if (checked) {
+        //ui->debugTab->show();
+        //ui->tabWidget->setTabEnabled(idx,true);
+    } else {
+        //ui->debugTab->hide();
+       // ui->tabWidget->setTabEnabled(idx,false);
+    }
+}
diff --git a/mainwindow.h b/mainwindow.h
index 6d719b4c..bf4abace 100644
--- a/mainwindow.h
+++ b/mainwindow.h
@@ -25,6 +25,7 @@ class MainWindow : public QMainWindow
 public:
     explicit MainWindow(QWidget *parent = 0);
     ~MainWindow();
+    void Log(QString s);
 
 private slots:
     void on_action_Import_Data_triggered();
@@ -63,6 +64,8 @@ private slots:
 
     void on_action_Noon_Date_Split_toggled(bool );
 
+    void on_actionDebug_toggled(bool arg1);
+
 private:
     Ui::MainWindow *ui;
     Daily * daily;
diff --git a/mainwindow.ui b/mainwindow.ui
index d63dfe5e..cce5fb80 100644
--- a/mainwindow.ui
+++ b/mainwindow.ui
@@ -76,7 +76,7 @@
        <enum>QTabWidget::North</enum>
       </property>
       <property name="currentIndex">
-       <number>0</number>
+       <number>1</number>
       </property>
       <property name="documentMode">
        <bool>false</bool>
@@ -546,6 +546,20 @@
         </item>
        </layout>
       </widget>
+      <widget class="QWidget" name="debugTab">
+       <attribute name="title">
+        <string>Debug</string>
+       </attribute>
+       <layout class="QVBoxLayout" name="verticalLayout_3">
+        <item>
+         <widget class="QPlainTextEdit" name="logText">
+          <property name="readOnly">
+           <bool>true</bool>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </widget>
      </widget>
     </item>
    </layout>
@@ -593,6 +607,8 @@
     <property name="title">
      <string>&amp;Help</string>
     </property>
+    <addaction name="actionDebug"/>
+    <addaction name="separator"/>
     <addaction name="action_About"/>
    </widget>
    <addaction name="menu_File"/>
@@ -692,6 +708,14 @@
     <string>&amp;Noon Date Split</string>
    </property>
   </action>
+  <action name="actionDebug">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>Debug</string>
+   </property>
+  </action>
  </widget>
  <customwidgets>
   <customwidget>
diff --git a/oximetry.cpp b/oximetry.cpp
index d92daae7..8a3a0c49 100644
--- a/oximetry.cpp
+++ b/oximetry.cpp
@@ -140,8 +140,8 @@ void Oximetry::on_RunButton_toggled(bool checked)
         plethy->SetMinX(double(lasttime)/86400000.0);
         plethy->SetMaxX(double(lasttime+30000)/86400000.0);
         plethy->SetRealMinY(0);
-        plethy->SetRealMaxY(120);
-        plethy->SetMaxY(120);
+        plethy->SetRealMaxY(130);
+        plethy->SetMaxY(130);
         plethy->SetMinY(0);
         PLETHY->MinX();
         PLETHY->MaxX();
@@ -250,6 +250,64 @@ void Oximetry::on_SerialPortsCombo_activated(const QString &arg1)
 {
     portname=arg1;
 }
+void Oximetry::UpdatePlethy(qint8 d)
+{
+    plethy->point[0][plethy->np[0]].setX(double(lasttime)/86400000.0);
+    plethy->point[0][plethy->np[0]++].setY(d);
+    lasttime+=20;  // 50 samples per second?
+    plethy->SetRealMaxX(lasttime/86400000.0);
+    if (plethy->RealMaxX()-plethy->RealMinX()>(1.0/(24.0*120.0))) {
+        plethy->SetMinX(lasttime/86400000.0-(1.0/(24.0*120.0)));
+        plethy->SetMaxX(lasttime/86400000.0);
+    }
+    PLETHY->MinX();
+    PLETHY->MaxX();
+    PLETHY->RealMaxX();
+    if (plethy->np[0]>max_data_points) {
+        //TODO: Stop Serial recording..
+
+        // for now overwrite..
+        plethy->np[0]=0;
+        lasttime=0;
+    }
+    //PLETHY->updateGL(); // Move this to a timer.
+}
+bool Oximetry::UpdatePulseSPO2(qint8 pul,qint8 sp)
+{
+    bool ret=false;
+    if (lastpulse!=pul) {
+        pulse->point[0][pulse->np[0]].setX(double(lasttime)/86400000.0);
+        pulse->point[0][pulse->np[0]++].setY(pul);
+        PULSE->updateGL();
+        if (pulse->np[0]>max_data_points) {
+            //TODO: Stop Serial recording..
+
+            // for now overwrite..
+            pulse->np[0]=0;
+            lasttime=0;
+        }
+        ret=true;
+        //qDebug() << "Pulse=" << int(bytes[0]);
+    }
+    if (lastspo2!=sp) {
+        spo2->point[0][spo2->np[0]].setX(double(lasttime)/86400000.0);
+        spo2->point[0][spo2->np[0]++].setY(sp);
+        SPO2->updateGL();
+        if (spo2->np[0]>max_data_points) {
+            //TODO: Stop Serial recording..
+
+            // for now overwrite..
+            spo2->np[0]=0;
+            lasttime=0;
+        }
+        ret=true;
+        //qDebug() << "SpO2=" << int(bytes[1]);
+    }
+
+    lastpulse=pul;
+    lastspo2=sp;
+    return ret;
+}
 
 void Oximetry::onReadyRead()
 {
@@ -259,68 +317,35 @@ void Oximetry::onReadyRead()
     bytes.resize(a);
     port->read(bytes.data(), bytes.size());
 
-    const int max_data_points=1000000;
-    if (bytes.size()==3) {
-        EventDataType d=bytes[1] & 0x7f;
-        plethy->point[0][plethy->np[0]].setX(double(lasttime)/86400000.0);
-        plethy->point[0][plethy->np[0]++].setY(d);
-        lasttime+=20;  // 50 samples per second?
-        plethy->SetRealMaxX(lasttime/86400000.0);
-        if (plethy->RealMaxX()-plethy->RealMinX()>(1.0/(24.0*120.0))) {
-            plethy->SetMinX(lasttime/86400000.0-(1.0/(24.0*120.0)));
-            plethy->SetMaxX(lasttime/86400000.0);
+    int i=0;
+    bool redraw_ps=false;
+    while (i<bytes.size()) {
+        if (bytes[i]&0x80) {
+            EventDataType d=bytes[i+1] & 0x7f;
+            UpdatePlethy(d);
+            i+=3;
+        } else {
+            if (UpdatePulseSPO2(bytes[i], bytes[i+1])) redraw_ps=true;
+            i+=2;
         }
-        PLETHY->MinX();
-        PLETHY->MaxX();
-        PLETHY->RealMaxX();
-        if (plethy->np[0]>max_data_points) {
-            //TODO: Stop Serial recording..
-
-            // for now overwrite..
-            plethy->np[0]=0;
-            lasttime=0;
-        }
-        PLETHY->updateGL(); // Move this to a timer.
     }
-    if (bytes.size()==2) { // Data bytes in live mode
+    PLETHY->updateGL();
+    if (redraw_ps) {
+        PULSE->updateGL();
+        SPO2->updateGL();
+    }
+    /*if (bytes.size()==3) {
+    } else if (bytes.size()==2) { // Data bytes in live mode
         // Plethy data
-        if (lastpulse!=bytes[0]) {
-            pulse->point[0][pulse->np[0]].setX(double(lasttime)/86400000.0);
-            pulse->point[0][pulse->np[0]++].setY(bytes[0]);
-            //pulse->SetMinX(lasttime/86400000.0-(1.0/(24.0*15.0)));
-            //pulse->SetMaxX(lasttime/86400000.0);
-            //pulse->SetRealMaxX(lasttime/86400000.0);
-            //PULSE->MinX();
-            //PULSE->MaxX();
-            //PULSE->RealMaxX();
-            PULSE->updateGL();
-            if (pulse->np[0]>max_data_points) {
-                //TODO: Stop Serial recording..
-
-                // for now overwrite..
-                pulse->np[0]=0;
-                lasttime=0;
-            }
-            //qDebug() << "Pulse=" << int(bytes[0]);
-        }
-        if (lastspo2!=bytes[1]) {
-            spo2->point[0][spo2->np[0]].setX(double(lasttime)/86400000.0);
-            spo2->point[0][spo2->np[0]++].setY(bytes[1]);
-            SPO2->updateGL();
-            if (spo2->np[0]>max_data_points) {
-                //TODO: Stop Serial recording..
-
-                // for now overwrite..
-                spo2->np[0]=0;
-                lasttime=0;
-            }
-
-            //qDebug() << "SpO2=" << int(bytes[1]);
-        }
-
-        lastpulse=bytes[0];
-        lastspo2=bytes[1];
+    } else {
+        //qDebug() << "Got " << bytes.size() << " bytes";
+    }*/
+    QString aa=QString::number(bytes.size(),16)+"bytes: ";
+    for (int i=0;i<bytes.size();i++) {
+        aa+=" "+QString::number((unsigned char)bytes[i],16);
     }
+    qDebug() << aa;
+
     lastsize=bytes.size();
 }
 void Oximetry::onDsrChanged(bool status)
diff --git a/oximetry.h b/oximetry.h
index b495db21..cc2d9063 100644
--- a/oximetry.h
+++ b/oximetry.h
@@ -14,6 +14,7 @@ namespace Ui {
 }
 
 enum PORTMODE { PM_LIVE, PM_RECORDING };
+const int max_data_points=1000000;
 
 class Oximetry : public QWidget
 {
@@ -23,8 +24,8 @@ public:
     explicit Oximetry(QWidget *parent = 0);
     ~Oximetry();
 
-    void AddData(gPointData *d) { Data.push_back(d);  };
-    void AddGraph(gGraphWindow *w) { Graphs.push_back(w); };
+    void AddData(gPointData *d) { Data.push_back(d);  }
+    void AddGraph(gGraphWindow *w) { Graphs.push_back(w); }
     void RedrawGraphs();
 
 private slots:
@@ -39,6 +40,10 @@ private slots:
     void on_ImportButton_clicked();
 
 private:
+    bool UpdatePulseSPO2(qint8 pulse,qint8 spo2);
+    void UpdatePlethy(qint8 plethy);
+
+
     Ui::Oximetry *ui;
     Profile *profile;
     QSplitter *gSplitter;