diff --git a/src/atcore.h b/src/atcore.h
--- a/src/atcore.h
+++ b/src/atcore.h
@@ -59,6 +59,8 @@
     Q_PROPERTY(QStringList portSpeeds READ portSpeeds)
     Q_PROPERTY(QString connectedPort READ connectedPort)
     Q_PROPERTY(AtCore::STATES state READ state WRITE setState NOTIFY stateChanged)
+    Q_PROPERTY(bool sdMount READ isSdMounted WRITE setSdMounted NOTIFY sdMountChanged)
+    Q_PROPERTY(QStringList sdFileList READ sdFileList NOTIFY sdCardFileListChanged)
 public:
     /**
      * @brief STATES enum Possible states the printer can be in
@@ -200,6 +202,59 @@
     */
     quint16 serialTimerInterval() const;
 
+    /**
+     * @brief Attempt to Mount an sd card
+     * @param slot: Sd card Slot on machine (0 is default)
+     */
+    void mountSd(uint slot = 0);
+
+    /**
+     * @brief Attempt to Unmount an sd card
+     * @param slot: Sd card Slot on machine (0 is default)
+     */
+    void umountSd(uint slot = 0);
+
+    /**
+     * @brief sdFileList
+     * @return List of files on the sd card.
+     */
+    QStringList sdFileList();
+
+    /**
+     * @brief Append a file to AtCorePrivate::sdCardFileList.
+     * @param fileName: new FileName
+     */
+    void appendSdCardFileList(const QString &fileName);
+
+    /**
+     * @brief Clear AtCorePrivate::sdCardFileList.
+     */
+    void clearSdCardFileList();
+
+    /**
+     * @brief Check if an sd card is mounted on the printer
+     * @return True if card mounted
+     */
+    bool isSdMounted() const;
+
+    /**
+     * @brief Set if the sd card is mounted by the printer
+     * @param mounted: True is mounted
+     */
+    void setSdMounted(const bool mounted);
+
+    /**
+     * @brief returns AtCorePrivate::sdCardReadingFileList
+     * @return True if printer is returning sd card file list
+     */
+    bool isReadingSdCardList() const;
+
+    /**
+     * @brief set AtCorePrivate::sdCardReadingFileList
+     * @param readingList set true if reading file list
+     */
+    void setReadingSdCardList(bool readingList);
+
 signals:
 
     /**
@@ -225,7 +280,17 @@
     /**
      * @brief Available serialports Changed
      */
-    void portsChanged(QStringList);
+    void portsChanged(const QStringList &portList);
+
+    /**
+     * @brief Sd Card Mount Changed
+     */
+    void sdMountChanged(bool newState);
+
+    /**
+     * @brief The files on the sd card have changed.
+     */
+    void sdCardFileListChanged(const QStringList &fileList);
 
 public slots:
 
@@ -246,8 +311,9 @@
     /**
      * @brief Public Interface for printing a file
      * @param fileName: the gcode file to print.
+     * @param sdPrint: set true to print fileName from Sd card
      */
-    void print(const QString &fileName);
+    void print(const QString &fileName, bool sdPrint);
 
     /**
      * @brief Stop the Printer by empting the queue and aborting the print job (if running)
@@ -378,6 +444,16 @@
      */
     void setSerialTimerInterval(const quint16 &newTime);
 
+    /**
+     * @brief delete file from sd card
+     */
+    void sdDelete(const QString &fileName);
+
+    /**
+     * @brief Queue the Printer for status of sd card print
+     */
+    void sdCardPrintStatus();
+
 private slots:
     /**
      * @brief processQueue send commands from the queue.
@@ -407,6 +483,11 @@
      */
     void locateSerialPort();
 
+    /**
+     * @brief Send request to the printer for the sd card file list.
+     */
+    void getSDFileList();
+
 private:
     /**
      * @brief True if a firmware plugin is loaded
@@ -428,6 +509,12 @@
      */
     void findFirmwarePlugins();
 
+    /**
+     * @brief stops print just for sd prints used internally
+     * @sa stop(),emergencyStop()
+     */
+    void stopSdPrint();
+
     /**
      * @brief Hold private data of AtCore.
      */
diff --git a/src/atcore.cpp b/src/atcore.cpp
--- a/src/atcore.cpp
+++ b/src/atcore.cpp
@@ -61,6 +61,11 @@
     AtCore::STATES printerState;        //!< @param printerState: State of the Printer
     QStringList serialPorts;            //!< @param seralPorts: Detected serial Ports
     QTimer *serialTimer = nullptr;      //!< @param serialTimer: Timer connected to locateSerialPorts
+    bool sdCardMounted = false;         //!< @param sdCardMounted: True if Sd Card is mounted.
+    bool sdCardReadingFileList = false; //!< @param sdCardReadingFileList: True while getting file names from sd card
+    bool sdCardPrinting = false;        //!< @param sdCardPrinting: True if currently printing from sd card.
+    QString sdCardFileName;             //!< @param sdCardFileName: name of file being used from sd card.
+    QStringList sdCardFileList;         //!< @param sdCardFileList: List of files on sd card.
 };
 
 AtCore::AtCore(QObject *parent) :
@@ -325,14 +330,23 @@
     return d->percentage;
 }
 
-void AtCore::print(const QString &fileName)
+void AtCore::print(const QString &fileName, bool sdPrint)
 {
     if (state() == AtCore::CONNECTING) {
         qCDebug(ATCORE_CORE) << "Load a firmware plugin to print.";
         return;
     }
-    //START A THREAD AND CONNECT TO IT
     setState(AtCore::STARTPRINT);
+    if (sdPrint) {
+        pushCommand(GCode::toCommand(GCode::M23, fileName));
+        d->sdCardFileName = fileName;
+        pushCommand(GCode::toCommand(GCode::M24));
+        setState(AtCore::BUSY);
+        d->sdCardPrinting = true;
+        connect(d->tempTimer, &QTimer::timeout, this, &AtCore::sdCardPrintStatus);
+        return;
+    }
+    //START A THREAD AND CONNECT TO IT
     QThread *thread = new QThread();
     PrintThread *printThread = new PrintThread(this, fileName);
     printThread->moveToThread(thread);
@@ -357,8 +371,9 @@
 void AtCore::closeConnection()
 {
     if (serialInitialized()) {
-        if (state() == AtCore::BUSY) {
-            //we have to clean print if printing.
+        if (AtCore::state() == AtCore::BUSY && !d->sdCardPrinting) {
+            //we have to clean print if printing from the host.
+            //disconnecting from a printer printing via sd card should not affect its print.
             setState(AtCore::STOP);
         }
         if (firmwarePluginLoaded()) {
@@ -373,6 +388,7 @@
         QString msg = d->pluginLoader.unload() ? QStringLiteral("success") : QStringLiteral("FAIL");
         qCDebug(ATCORE_PLUGIN) << QStringLiteral("Firmware plugin %1 unload: %2").arg(name, msg);
         serial()->close();
+        clearSdCardFileList();
         setState(AtCore::DISCONNECTED);
     }
 }
@@ -388,28 +404,47 @@
         qCDebug(ATCORE_CORE) << "Atcore state changed from [" \
                              << d->printerState << "] to [" << state << "]";
         d->printerState = state;
+        if (state == AtCore::FINISHEDPRINT && d->sdCardPrinting) {
+            d->sdCardPrinting = false;
+            disconnect(d->tempTimer, &QTimer::timeout, this, &AtCore::sdCardPrintStatus);
+        }
         emit(stateChanged(d->printerState));
     }
 }
 
 void AtCore::stop()
 {
     setState(AtCore::STOP);
     d->commandQueue.clear();
+    if (d->sdCardPrinting) {
+        stopSdPrint();
+    }
     setExtruderTemp(0, 0);
     setBedTemp(0);
     home(AtCore::X);
 }
 
 void AtCore::emergencyStop()
 {
-    if (state() == AtCore::BUSY) {
-        setState(AtCore::STOP);
-    }
     d->commandQueue.clear();
+    if (AtCore::state() == AtCore::BUSY) {
+        if (!d->sdCardPrinting) {
+            //Stop our running print thread
+            setState(AtCore::STOP);
+        }
+    }
     serial()->pushCommand(GCode::toCommand(GCode::M112).toLocal8Bit());
 }
 
+void AtCore::stopSdPrint()
+{
+    pushCommand(GCode::toCommand(GCode::M25));
+    d->sdCardFileName = QString();
+    pushCommand(GCode::toCommand(GCode::M23, d->sdCardFileName));
+    AtCore::setState(AtCore::FINISHEDPRINT);
+    AtCore::setState(AtCore::IDLE);
+}
+
 void AtCore::requestFirmware()
 {
     if (serialInitialized()) {
@@ -472,19 +507,26 @@
 
 void AtCore::pause(const QString &pauseActions)
 {
+    if (d->sdCardPrinting) {
+        pushCommand(GCode::toCommand(GCode::M25));
+    }
     pushCommand(GCode::toCommand(GCode::M114));
-    setState(AtCore::PAUSE);
     if (!pauseActions.isEmpty()) {
         QStringList temp = pauseActions.split(QChar::fromLatin1(','));
         for (int i = 0; i < temp.length(); i++) {
             pushCommand(temp.at(i));
         }
     }
+    setState(AtCore::PAUSE);
 }
 
 void AtCore::resume()
 {
-    pushCommand(GCode::toCommand(GCode::G0, QString::fromLatin1(d->posString)));
+    if (d->sdCardPrinting) {
+        pushCommand(GCode::toCommand(GCode::M24));
+    } else {
+        pushCommand(GCode::toCommand(GCode::G0, QString::fromLatin1(d->posString)));
+    }
     setState(AtCore::BUSY);
 }
 
@@ -628,3 +670,74 @@
         pushCommand(GCode::toCommand(GCode::M84));
     }
 }
+
+bool AtCore::isSdMounted() const
+{
+    return d->sdCardMounted;
+}
+
+void AtCore::setSdMounted(bool mounted)
+{
+    if (mounted != isSdMounted()) {
+        d->sdCardMounted = mounted;
+        emit(sdMountChanged(d->sdCardMounted));
+    }
+}
+
+void AtCore::getSDFileList()
+{
+    pushCommand(GCode::toCommand(GCode::M20));
+}
+
+QStringList AtCore::sdFileList()
+{
+    if (!d->sdCardReadingFileList) {
+        getSDFileList();
+    }
+    return d->sdCardFileList;
+}
+
+void AtCore::appendSdCardFileList(const QString &fileName)
+{
+    d->sdCardFileList.append(fileName);
+    emit(sdCardFileListChanged(d->sdCardFileList));
+}
+
+void AtCore::clearSdCardFileList()
+{
+    d->sdCardFileList.clear();
+    emit(sdCardFileListChanged(d->sdCardFileList));
+}
+
+void AtCore::sdDelete(const QString &fileName)
+{
+    if (d->sdCardFileList.contains(fileName)) {
+        pushCommand(GCode::toCommand(GCode::M30, fileName));
+        getSDFileList();
+    }
+}
+
+void AtCore::mountSd(uint slot)
+{
+    pushCommand(GCode::toCommand(GCode::M21, QString::number(slot)));
+}
+
+void AtCore::umountSd(uint slot)
+{
+    pushCommand(GCode::toCommand(GCode::M22, QString::number(slot)));
+}
+
+bool AtCore::isReadingSdCardList() const
+{
+    return d->sdCardReadingFileList;
+}
+
+void AtCore::setReadingSdCardList(bool readingList)
+{
+    d->sdCardReadingFileList = readingList;
+}
+
+void AtCore::sdCardPrintStatus()
+{
+    pushCommand(GCode::toCommand(GCode::M27));
+}
diff --git a/src/gcodecommands.cpp b/src/gcodecommands.cpp
--- a/src/gcodecommands.cpp
+++ b/src/gcodecommands.cpp
@@ -96,13 +96,15 @@
     case G90:
     case G91:
         return code;
+
     case G32:
         return code.append(QStringLiteral(" S1"));
     case G0:
     case G1:
     case G28:
         code = value1.isEmpty() ? code : code.append(QStringLiteral(" %1").arg(value1.toUpper()));
         return code;
+
     default:
         return commandNotSupported;
     }
@@ -129,7 +131,7 @@
         return QObject::tr("M21: Initialize SDCard");
     case M22://Teacup - Sprinter - Marlin - Repetier - RepRap Firmware
         return QObject::tr("M22: Release SDCard");
-    case M23:////Teacup - Sprinter - Marlin - Repetier - Smoothie - RepRap Firmware
+    case M23://Teacup - Sprinter - Marlin - Repetier - Smoothie - RepRap Firmware
         return QObject::tr("M23: Select SD file");
     case M24://Teacup - Sprinter - Marlin - Repetier - Smoothie - RepRap Firmware
         return QObject::tr("M24: Start/resume SD print");
@@ -289,7 +291,7 @@
         return QObject::tr("M231: Set OPS parameter");
     case M232://Repetier
         return QObject::tr("M232: Read and reset max. advance values");
-    case M240: //Marlin
+    case M240://Marlin
         return QObject::tr("M240: Trigger camera");
     case M250://Marlin
         return QObject::tr("M250: Set LCD contrast");
@@ -494,35 +496,68 @@
 {
     QString code = QStringLiteral("M%1").arg(QString::number(gcode));
     switch (gcode) {
+    case M20:
+    case M24:
+    case M25:
+    case M27:
     case M105:
     case M107:
     case M112:
     case M114:
     case M115:
     case M116:
     case M119:
         return code;
+
+    case M21:
+    case M22:
+        code = value1.isEmpty() ? code : code.append(QStringLiteral(" P%1").arg(value1));
+        return code;
+
+    case M23:
+    case M28:
+    case M29:
+    case M30:
     case M117:
-        code = value1.isEmpty() ? GCode::commandRequiresArgument.arg(QStringLiteral("M"), QString::number(gcode)) : QStringLiteral("M117 %1").arg(value1);
+        code = value1.isEmpty() ? GCode::commandRequiresArgument.arg(QStringLiteral("M"), QString::number(gcode)) : code.append(QStringLiteral(" %1").arg(value1));
         return code;
+
     case M109:
     case M140:
     case M190:
     case M220:
     case M221:
         code = value1.isEmpty() ? GCode::commandRequiresArgument.arg(QStringLiteral("M"), QString::number(gcode)) : code.append(QStringLiteral(" S%1").arg(value1));
         return code;
+
     case M84:
         code = value1.isEmpty() ? code : code.append(QStringLiteral(" S%1").arg(value1));
         return code;
+
     case M104:
         code = value2.isEmpty() ? code.append(QStringLiteral(" S%1").arg(value1)) : code.append(QStringLiteral(" P%1 S%2").arg(value1).arg(value2));
         code = value1.isEmpty() ? GCode::commandRequiresArgument.arg(QStringLiteral("M"), QString::number(gcode)) : code ;
         return code;
+
     case M106:
         code = value2.isEmpty() ? code.append(QStringLiteral(" S%1").arg(value1)) : code.append(QStringLiteral(" P%1 S%2").arg(value1).arg(value2));
         code = value1.isEmpty() ? QStringLiteral("M106") : code ;
         return code;
+
+    /// For M26 values that end with %. AtCore will send the percentage verison of the command (optional in firmwares)
+    /// For all values not ending in % it will start on that byte. This is the standard Sd resume supported by all reprap based firmware.
+    case M26: {
+        if (!value1.isEmpty()) {
+            if (value1.endsWith(QStringLiteral("%"))) {
+                QString temp = value1;
+                temp.replace(QStringLiteral("%"), QStringLiteral(""));
+                return code.append(QStringLiteral(" P%1").arg(temp.toDouble() / 100));
+            }
+            return code.append(QStringLiteral(" S%1").arg(value1));
+        }
+        return GCode::commandRequiresArgument.arg(QStringLiteral("M"), QString::number(gcode));
+    }
+
     default:
         return commandNotSupported;
     }
diff --git a/src/plugins/marlinplugin.h b/src/plugins/marlinplugin.h
--- a/src/plugins/marlinplugin.h
+++ b/src/plugins/marlinplugin.h
@@ -48,4 +48,10 @@
      * @return Marlin
      */
     QString name() const override;
+
+    /**
+     * @brief validateCommand to filter commands from messages
+     * @param lastMessage: last Message from printer
+     */
+    void validateCommand(const QString &lastMessage) override;
 };
diff --git a/src/plugins/marlinplugin.cpp b/src/plugins/marlinplugin.cpp
--- a/src/plugins/marlinplugin.cpp
+++ b/src/plugins/marlinplugin.cpp
@@ -39,3 +39,47 @@
 {
     qCDebug(MARLIN_PLUGIN) << name() << " plugin loaded!";
 }
+
+void MarlinPlugin::validateCommand(const QString &lastMessage)
+{
+    if (lastMessage.contains(QStringLiteral("End file list"))) {
+        core()->setReadingSdCardList(false);
+    } else if (core()->isReadingSdCardList()) {
+        // Below is to not add directories
+        if (!lastMessage.endsWith(QChar::fromLatin1('/'))) {
+            QString fileName = lastMessage;
+            fileName.chop(fileName.length() - fileName.lastIndexOf(QChar::fromLatin1(' ')));
+            core()->appendSdCardFileList(fileName);
+        }
+    } else {
+        if (lastMessage.contains(QStringLiteral("SD card ok"))) {
+            core()->setSdMounted(true);
+        } else if (lastMessage.contains(QStringLiteral("SD init fail"))) {
+            core()->setSdMounted(false);
+        } else if (lastMessage.contains(QStringLiteral("Begin file list"))) {
+            core()->setSdMounted(true);
+            core()->clearSdCardFileList();
+            core()->setReadingSdCardList(true);
+        } else if (lastMessage.contains(QStringLiteral("SD printing byte"))) {
+            QString temp = lastMessage;
+            temp.replace(QStringLiteral("SD printing byte"), QString());
+            qlonglong total = temp.mid(temp.lastIndexOf(QChar::fromLatin1('/')) + 1, temp.length() - temp.lastIndexOf(QChar::fromLatin1('/'))).toLongLong();
+            if (total != 0) {
+                temp.chop(temp.length() - temp.lastIndexOf(QChar::fromLatin1('/')));
+                qlonglong remaining = total - temp.toLongLong();
+                float progress = float(total - remaining) * 100 / float(total);
+                core()->printProgressChanged(progress);
+                if (progress >= 100) {
+                    core()->setState(AtCore::FINISHEDPRINT);
+                    core()->setState(AtCore::IDLE);
+                }
+            } else {
+                core()->setState(AtCore::FINISHEDPRINT);
+                core()->setState(AtCore::IDLE);
+            }
+        }
+        if (lastMessage.contains(QStringLiteral("ok"))) {
+            emit readyForCommand();
+        }
+    }
+}
diff --git a/src/plugins/repetierplugin.h b/src/plugins/repetierplugin.h
--- a/src/plugins/repetierplugin.h
+++ b/src/plugins/repetierplugin.h
@@ -48,4 +48,10 @@
      * @return Repetier
      */
     QString name() const override;
+
+    /**
+     * @brief validateCommand to filter commands from messages
+     * @param lastMessage: last Message from printer
+     */
+    void validateCommand(const QString &lastMessage) override;
 };
diff --git a/src/plugins/repetierplugin.cpp b/src/plugins/repetierplugin.cpp
--- a/src/plugins/repetierplugin.cpp
+++ b/src/plugins/repetierplugin.cpp
@@ -39,3 +39,49 @@
 {
     qCDebug(REPETIER_PLUGIN) << name() << " plugin loaded!";
 }
+
+void RepetierPlugin::validateCommand(const QString &lastMessage)
+{
+    if (lastMessage.contains(QStringLiteral("End file list"))) {
+        core()->setReadingSdCardList(false);
+    } else if (core()->isReadingSdCardList()) {
+        // Below is to not add directories
+        if (!lastMessage.endsWith(QChar::fromLatin1('/'))) {
+            QString fileName = lastMessage;
+            fileName.chop(fileName.length() - fileName.lastIndexOf(QChar::fromLatin1(' ')));
+            core()->appendSdCardFileList(fileName);
+        }
+    } else {
+        if (lastMessage.contains(QStringLiteral("SD card"))) {
+            if (lastMessage.contains(QStringLiteral("inserted"))) {
+                core()->setSdMounted(true);
+            } else if (lastMessage.contains(QStringLiteral("removed"))) {
+                core()->setSdMounted(false);
+            }
+        } else if (lastMessage.contains(QStringLiteral("Begin file list"))) {
+            core()->setSdMounted(true);
+            core()->setReadingSdCardList(true);
+            core()->clearSdCardFileList();
+        } else if (lastMessage.contains(QStringLiteral("SD printing byte"))) {
+            QString temp = lastMessage;
+            temp.replace(QStringLiteral("SD printing byte"), QString());
+            qlonglong total = temp.mid(temp.lastIndexOf(QChar::fromLatin1('/')) + 1, temp.length() - temp.lastIndexOf(QChar::fromLatin1('/'))).toLongLong();
+            if (total != 0) {
+                temp.chop(temp.length() - temp.lastIndexOf(QChar::fromLatin1('/')));
+                qlonglong remaining = total - temp.toLongLong();
+                float progress = float(total - remaining) * 100 / float(total);
+                core()->printProgressChanged(progress);
+                if (progress >= 100) {
+                    core()->setState(AtCore::FINISHEDPRINT);
+                    core()->setState(AtCore::IDLE);
+                }
+            } else {
+                core()->setState(AtCore::FINISHEDPRINT);
+                core()->setState(AtCore::IDLE);
+            }
+        }
+        if (lastMessage.contains(QStringLiteral("ok"))) {
+            emit readyForCommand();
+        }
+    }
+}
diff --git a/testclient/mainwindow.h b/testclient/mainwindow.h
--- a/testclient/mainwindow.h
+++ b/testclient/mainwindow.h
@@ -131,6 +131,10 @@
      */
     void printPBClicked();
 
+    /**
+     * @brief Print Button for Sd Prints clicked.
+     */
+    void sdPrintPBClicked();
     /**
      * @brief Save the log file.
      */
@@ -176,12 +180,24 @@
      * @brief Show the about dialog
      */
     void about();
+
+    /**
+     * @brief List Files on the sd card.
+     */
+    void getSdList();
+
+    /**
+     * @brief Sd Card Delete file clicked
+     */
+    void sdDelPBClicked();
+
 signals:
     /**
      * @brief printFile emit ready to print a file to atcore
      * @param fileName : the file to print
+     * @param sdPrint : True if file is on printers Sd Card
      */
-    void printFile(const QString &fileName);
+    void printFile(const QString &fileName, bool sdPrint = false);
 
 private:
     Ui::MainWindow *ui;
@@ -269,4 +285,9 @@
      * @brief Populate comboboxes
      */
     void populateCBs();
+
+    /**
+     * @brief Gui Changes for when sd card mount status has changed.
+     */
+    void sdChanged(bool mounted);
 };
diff --git a/testclient/mainwindow.cpp b/testclient/mainwindow.cpp
--- a/testclient/mainwindow.cpp
+++ b/testclient/mainwindow.cpp
@@ -90,18 +90,27 @@
     connect(ui->mvAxisPB, &QPushButton::clicked, this, &MainWindow::mvAxisPBClicked);
     connect(ui->fanSpeedPB, &QPushButton::clicked, this, &MainWindow::fanSpeedPBClicked);
     connect(ui->printPB, &QPushButton::clicked, this, &MainWindow::printPBClicked);
+    connect(ui->sdPrintPB, &QPushButton::clicked, this, &MainWindow::sdPrintPBClicked);
+    connect(ui->sdDelPB, &QPushButton::clicked, this, &MainWindow::sdDelPBClicked);
     connect(ui->printerSpeedPB, &QPushButton::clicked, this, &MainWindow::printerSpeedPBClicked);
     connect(ui->flowRatePB, &QPushButton::clicked, this, &MainWindow::flowRatePBClicked);
     connect(ui->showMessagePB, &QPushButton::clicked, this, &MainWindow::showMessage);
     connect(ui->pluginCB, &QComboBox::currentTextChanged, this, &MainWindow::pluginCBChanged);
     connect(ui->disableMotorsPB, &QPushButton::clicked, this, &MainWindow::disableMotorsPBClicked);
+    connect(ui->sdListPB, &QPushButton::clicked, this, &MainWindow::getSdList);
     connect(core, &AtCore::stateChanged, this, &MainWindow::printerStateChanged);
     connect(this, &MainWindow::printFile, core, &AtCore::print);
     connect(ui->stopPB, &QPushButton::clicked, core, &AtCore::stop);
     connect(ui->emergencyStopPB, &QPushButton::clicked, core, &AtCore::emergencyStop);
     connect(axisControl, &AxisControl::clicked, this, &MainWindow::axisControlClicked);
     connect(core, &AtCore::portsChanged, this, &MainWindow::locateSerialPort);
     connect(core, &AtCore::printProgressChanged, this, &MainWindow::printProgressChanged);
+    connect(core, &AtCore::sdMountChanged, this, &MainWindow::sdChanged);
+
+    connect(core, &AtCore::sdCardFileListChanged, [this](QStringList fileList) {
+        ui->sdFileListView->clear();
+        ui->sdFileListView->addItems(fileList);
+    });
 
     connect(&core->temperature(), &Temperature::bedTemperatureChanged, [ this ](float temp) {
         checkTemperature(0x00, 0, temp);
@@ -135,11 +144,13 @@
     ui->menuView->insertAction(nullptr, ui->moveDock->toggleViewAction());
     ui->menuView->insertAction(nullptr, ui->tempTimelineDock->toggleViewAction());
     ui->menuView->insertAction(nullptr, ui->logDock->toggleViewAction());
+    ui->menuView->insertAction(nullptr, ui->sdDock->toggleViewAction());
 
     //more dock stuff.
     setTabPosition(Qt::LeftDockWidgetArea, QTabWidget::North);
     setTabPosition(Qt::RightDockWidgetArea, QTabWidget::North);
     tabifyDockWidget(ui->moveDock, ui->tempControlsDock);
+    tabifyDockWidget(ui->moveDock, ui->sdDock);
     ui->moveDock->raise();
 
     tabifyDockWidget(ui->connectDock, ui->printDock);
@@ -488,14 +499,16 @@
         ui->moveDock->setDisabled(true);
         ui->tempControlsDock->setDisabled(true);
         ui->printDock->setDisabled(true);
+        ui->sdDock->setDisabled(true);
         break;
 
     case AtCore::CONNECTING:
         stateString = QStringLiteral("Connecting");
         ui->commandDock->setDisabled(false);
         ui->moveDock->setDisabled(false);
         ui->tempControlsDock->setDisabled(false);
         ui->printDock->setDisabled(false);
+        ui->sdDock->setDisabled(false);
         break;
 
     case AtCore::STOP:
@@ -553,14 +566,16 @@
         delete ui->moveDock->titleBarWidget();
         delete ui->tempControlsDock->titleBarWidget();
         delete ui->printDock->titleBarWidget();
+        delete ui->sdDock->titleBarWidget();
     } else {
         ui->connectDock->setTitleBarWidget(new QWidget());
         ui->logDock->setTitleBarWidget(new QWidget());
         ui->tempTimelineDock->setTitleBarWidget(new QWidget());
         ui->commandDock->setTitleBarWidget(new QWidget());
         ui->moveDock->setTitleBarWidget(new QWidget());
         ui->tempControlsDock->setTitleBarWidget(new QWidget());
         ui->printDock->setTitleBarWidget(new QWidget());
+        ui->sdDock->setTitleBarWidget(new QWidget());
     }
 }
 
@@ -581,3 +596,33 @@
 {
     core->setIdleHold(0);
 }
+
+void MainWindow::sdChanged(bool mounted)
+{
+    QString labelText = mounted ? QStringLiteral("SD") : QString();
+    ui->lbl_sd->setText(labelText);
+}
+
+void MainWindow::getSdList()
+{
+    core->sdFileList();
+}
+
+void MainWindow::sdPrintPBClicked()
+{
+    if (ui->sdFileListView->currentRow() < 0) {
+        QMessageBox::information(this, QStringLiteral("Print Error"), QStringLiteral("You must Select a file from the list"));
+    } else  {
+        core->print(ui->sdFileListView->currentItem()->text(), true);
+    }
+}
+
+void MainWindow::sdDelPBClicked()
+{
+    if (ui->sdFileListView->currentRow() < 0) {
+        QMessageBox::information(this, QStringLiteral("Delete Error"), QStringLiteral("You must Select a file from the list"));
+    } else  {
+        core->sdDelete(ui->sdFileListView->currentItem()->text());
+        ui->sdFileListView->setCurrentRow(-1);
+    }
+}
diff --git a/testclient/mainwindow.ui b/testclient/mainwindow.ui
--- a/testclient/mainwindow.ui
+++ b/testclient/mainwindow.ui
@@ -56,6 +56,41 @@
        </property>
       </widget>
      </item>
+     <item>
+      <spacer name="horizontalSpacer_2">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeType">
+        <enum>QSizePolicy::Fixed</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>10</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QFrame" name="frame">
+       <property name="frameShape">
+        <enum>QFrame::StyledPanel</enum>
+       </property>
+       <property name="frameShadow">
+        <enum>QFrame::Raised</enum>
+       </property>
+       <layout class="QHBoxLayout" name="horizontalLayout_14">
+        <item>
+         <widget class="QLabel" name="lbl_sd">
+          <property name="text">
+           <string/>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </widget>
+     </item>
      <item>
       <spacer name="horizontalSpacer">
        <property name="orientation">
@@ -380,6 +415,71 @@
      </layout>
     </widget>
    </widget>
+   <widget class="QDockWidget" name="sdDock">
+    <property name="enabled">
+     <bool>false</bool>
+    </property>
+    <property name="geometry">
+     <rect>
+      <x>0</x>
+      <y>42</y>
+      <width>515</width>
+      <height>317</height>
+     </rect>
+    </property>
+    <property name="windowTitle">
+     <string>S&amp;d Card</string>
+    </property>
+    <widget class="QWidget" name="dockWidgetContents_5">
+     <layout class="QVBoxLayout" name="verticalLayout_3">
+      <item>
+       <widget class="QFrame" name="frame_2">
+        <property name="frameShape">
+         <enum>QFrame::StyledPanel</enum>
+        </property>
+        <property name="frameShadow">
+         <enum>QFrame::Raised</enum>
+        </property>
+        <layout class="QHBoxLayout" name="horizontalLayout_18">
+         <item>
+          <widget class="QPushButton" name="sdListPB">
+           <property name="text">
+            <string>Get List</string>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <widget class="QPushButton" name="sdPrintPB">
+           <property name="text">
+            <string>Print Selected</string>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <widget class="QPushButton" name="sdDelPB">
+           <property name="text">
+            <string>Delete Selected</string>
+           </property>
+          </widget>
+         </item>
+        </layout>
+       </widget>
+      </item>
+      <item>
+       <widget class="QGroupBox" name="groupBox_3">
+        <property name="title">
+         <string>Files On Sd Card.</string>
+        </property>
+        <layout class="QVBoxLayout" name="verticalLayout_11">
+         <item>
+          <widget class="QListWidget" name="sdFileListView"/>
+         </item>
+        </layout>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </widget>
   </widget>
   <widget class="QDockWidget" name="tempTimelineDock">
    <property name="minimumSize">
diff --git a/unittests/gcodetests.h b/unittests/gcodetests.h
--- a/unittests/gcodetests.h
+++ b/unittests/gcodetests.h
@@ -35,6 +35,17 @@
     void command_unsupportedG();
 
     bool testMCodeNeedsArg(GCode::MCommands code);
+    void command_M20();
+    void command_M21();
+    void command_M22();
+    void command_M23();
+    void command_M24();
+    void command_M25();
+    void command_M26();
+    void command_M27();
+    void command_M28();
+    void command_M29();
+    void command_M30();
     void command_M84();
     void command_M104();
     void command_M105();
diff --git a/unittests/gcodetests.cpp b/unittests/gcodetests.cpp
--- a/unittests/gcodetests.cpp
+++ b/unittests/gcodetests.cpp
@@ -68,6 +68,70 @@
     return GCode::toCommand(code) == GCode::commandRequiresArgument.arg(QStringLiteral("M"), QString::number(code));
 }
 
+void GCodeTests::command_M20()
+{
+    QVERIFY(GCode::toCommand(GCode::M20) == QStringLiteral("M20"));
+}
+
+void GCodeTests::command_M21()
+{
+    QVERIFY(GCode::toCommand(GCode::M21) == QStringLiteral("M21"));
+    QVERIFY(GCode::toCommand(GCode::M21, QStringLiteral("2")) == QStringLiteral("M21 P2"));
+}
+
+void GCodeTests::command_M22()
+{
+    QVERIFY(GCode::toCommand(GCode::M22) == QStringLiteral("M22"));
+    QVERIFY(GCode::toCommand(GCode::M22, QStringLiteral("5")) == QStringLiteral("M22 P5"));
+}
+
+void GCodeTests::command_M23()
+{
+    QVERIFY(testMCodeNeedsArg(GCode::M23));
+    QVERIFY(GCode::toCommand(GCode::M23, QStringLiteral("FileName")) == QStringLiteral("M23 FileName"));
+}
+
+void GCodeTests::command_M24()
+{
+    QVERIFY(GCode::toCommand(GCode::M24) == QStringLiteral("M24"));
+}
+
+void GCodeTests::command_M25()
+{
+    QVERIFY(GCode::toCommand(GCode::M25) == QStringLiteral("M25"));
+}
+
+void GCodeTests::command_M26()
+{
+    QVERIFY(testMCodeNeedsArg(GCode::M26));
+    QVERIFY(GCode::toCommand(GCode::M26, QStringLiteral("15%")) == QStringLiteral("M26 P0.15"));
+    QVERIFY(GCode::toCommand(GCode::M26, QStringLiteral("15")) == QStringLiteral("M26 S15"));
+
+}
+
+void GCodeTests::command_M27()
+{
+    QVERIFY(GCode::toCommand(GCode::M27) == QStringLiteral("M27"));
+}
+
+void GCodeTests::command_M28()
+{
+    QVERIFY(testMCodeNeedsArg(GCode::M28));
+    QVERIFY(GCode::toCommand(GCode::M28, QStringLiteral("FileName")) == QStringLiteral("M28 FileName"));
+}
+
+void GCodeTests::command_M29()
+{
+    QVERIFY(testMCodeNeedsArg(GCode::M29));
+    QVERIFY(GCode::toCommand(GCode::M29, QStringLiteral("FileName")) == QStringLiteral("M29 FileName"));
+}
+
+void GCodeTests::command_M30()
+{
+    QVERIFY(testMCodeNeedsArg(GCode::M30));
+    QVERIFY(GCode::toCommand(GCode::M30, QStringLiteral("FileName")) == QStringLiteral("M30 FileName"));
+}
+
 void GCodeTests::command_M84()
 {
     QVERIFY(GCode::toCommand(GCode::M84) == QStringLiteral("M84"));