diff --git a/doc/docu.odt b/doc/docu.odt
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diff --git a/doc/docu.pdf b/doc/docu.pdf
index f5e2ba1..c07e8c4 100644
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diff --git a/emulator/qt/ll_filesystem.cpp b/emulator/qt/ll_filesystem.cpp
index a89e08d..8d1d47f 100644
--- a/emulator/qt/ll_filesystem.cpp
+++ b/emulator/qt/ll_filesystem.cpp
@@ -7,51 +7,53 @@ extern "C" {
 #include <QFileInfoList>
 #include <QDateTime>
 
-QDir rootdir ("./emulated");
+QDir rootdir ("./emulated"); //Create a QDir which points to the "root" of the emulated filesystem
 
 bool ll_filesystem_init() {
-    if(!rootdir.exists()) {
+    if(!rootdir.exists()) { //if our root dir is nonexistent
         qWarning() << "Filesystem can not be emulated because the 'emulated' folder does not exist";
-        return false;
+        return false; //mark an error
     }
     return true;
 }
 
 DIRECTORY_STRUCT* ll_filesystem_dir_open(const char* path) {
-    QDir d(rootdir);
-    d.cd(path);
+    QDir d(rootdir); //Make a copy of the rootdir QDir instance
+    d.cd(path); //Change the directory to the passed path
     if(!d.exists()) {
-        return NULL;
+        return NULL; //mark an error
     }
 
     DIRECTORY_STRUCT* directory = new DIRECTORY_STRUCT();
+    //get all files and directories which are important to us. Filter out . and .. symlinks (linux)
     QFileInfoList entries = d.entryInfoList(QDir::NoDotAndDotDot|QDir::Files|QDir::Dirs|QDir::Readable|QDir::Writable|QDir::Hidden|QDir::System);
+    //Fill the directory structure for the user
     directory->path = path;
     directory->num_files = entries.count();
-    directory->files =  new FILE_STRUCT[directory->num_files];
+    directory->files =  new FILE_STRUCT[directory->num_files]; //allocate array of file structs
 
-
-    for(int i=0; i<entries.count(); i++){
+    for(int i=0; i<entries.count(); i++){ //foreach file that we found
         QFileInfo fi = entries.at(i);
-        FILE_STRUCT* entry = &(directory->files[i]);
+        FILE_STRUCT* entry = &(directory->files[i]); //get the pointer to the current filestruct (which should be filled)
         entry->fattrib = 0;
-        entry->fname = new char[fi.fileName().length()+1];
-        strcpy(entry->fname,fi.fileName().toStdString().c_str());
-        if(fi.isDir()) {
-            entry->fattrib|=F_DIR;
+        entry->fname = new char[fi.fileName().length()+1]; //reserve memory for filename
+        strcpy(entry->fname,fi.fileName().toStdString().c_str()); //copy filename into struct
+        if(fi.isDir()) { //it's a direcory
+            entry->fattrib|=F_DIR; //set directory attribute
             entry->fsize = 0;
-        } else {
-            entry->fsize = fi.size();
+        } else { //it's a file
+            entry->fsize = fi.size(); //set filesize
         }
-        if(fi.isHidden()) {
+        if(fi.isHidden()) { //the file is hidden
             entry->fattrib|=F_HID;
         }
-        if(!fi.isWritable()) {
-            entry->fattrib|=F_RDO;
+        if(!fi.isWritable()) { //the file is not writable
+            entry->fattrib|=F_RDO; //set readonly attribue
         }
 
+        //Set date & time of file in structure
         QDateTime dt = fi.lastModified();
-        entry->fdate.year = dt.date().year()-1980;
+        entry->fdate.year = dt.date().year()-1980; //year is realtive to 1980
         entry->fdate.month = dt.date().month();
         entry->fdate.day = dt.date().day();
         entry->ftime.hour = dt.time().hour();
@@ -60,22 +62,22 @@ DIRECTORY_STRUCT* ll_filesystem_dir_open(const char* path) {
 
     }
 
-    return directory;
+    return directory; //return filled directory struct
 }
 
 void ll_filesystem_dir_close(DIRECTORY_STRUCT* dir) {
-    if(dir!=NULL) {
-        for(int i=0; i<dir->num_files; i++) {
-            delete dir->files[i].fname;
+    if(dir!=NULL) { //passed handle is valid
+        for(int i=0; i<dir->num_files; i++) { //foreach file
+            delete dir->files[i].fname; //delete filename buffer
         }
-        delete[] dir->files;
-        delete dir;
+        delete[] dir->files; //delete file array
+        delete dir; //delete structure itself
     }
 }
 
-
-struct QT_FILE_HANDLE : FILE_HANDLE {
-    QFile* file;
+//Struct that represents a file handle for the emulator
+struct QT_FILE_HANDLE : FILE_HANDLE { //..derived from the FILE_HANDLE (of the Filesystem modul)
+    QFile* file; //Pointer to the open QFile* instance
 };
 
 
@@ -83,17 +85,19 @@ FILE_HANDLE* ll_filesystem_file_open(const char* filename) {
     if(!rootdir.exists()) {
         return NULL;
     }
-    QString filepath = rootdir.absoluteFilePath(filename);
-    QFile* f = new QFile(filepath);
-    if(!f->exists()) {
-        return NULL;
+    QString filepath = rootdir.absoluteFilePath(filename); //get the absolute path to the requested file
+    QFile* f = new QFile(filepath); //create a QFile instance to the requested file
+    if(!f->exists()) { //File does not exist
+        return NULL; //mark error
     }
 
-    if(!f->open(QFile::ReadWrite)) {
-        return NULL;
+    if(!f->open(QFile::ReadWrite)) { //try to open the file, it it fails then ...
+        return NULL; //... mark error
     }
 
-    QT_FILE_HANDLE* fh = new QT_FILE_HANDLE();
+    //At this point we have a valid QFile instance, pointing to an existing file
+
+    QT_FILE_HANDLE* fh = new QT_FILE_HANDLE(); //Create Structure to return to user
     fh->file = f;
     fh->fname = filename;
     fh->fpos =0;
@@ -102,12 +106,13 @@ FILE_HANDLE* ll_filesystem_file_open(const char* filename) {
 }
 
 void ll_filesystem_file_close(FILE_HANDLE* handle) {
-    if(handle!=NULL) {
-        QT_FILE_HANDLE* fh = static_cast<QT_FILE_HANDLE*>(handle);
-        if(fh->file->isOpen()) {
-            fh->file->close();
+    if(handle!=NULL) { //passed handle is valid
+        QT_FILE_HANDLE* fh = static_cast<QT_FILE_HANDLE*>(handle); //cast pointer to QT_FILE_HANDLE
+        if(fh->file->isOpen()) { //if the file is still open
+            fh->file->close(); //close the file
         }
-        delete fh;
+        delete fh->file; //delete QFile instance
+        delete fh; //delete the fle
     }
 }
 
@@ -115,18 +120,18 @@ FILE_STATUS ll_filesystem_file_seek(FILE_HANDLE* handle, uint32_t offset) {
     if(handle==NULL) {
         return F_INVALIDPARAM;
     }
-    QT_FILE_HANDLE* fh = static_cast<QT_FILE_HANDLE*>(handle);
-    if(!fh->file->isOpen()) {
+    QT_FILE_HANDLE* fh = static_cast<QT_FILE_HANDLE*>(handle); //cast pointer to QT_FILE_HANDLE
+    if(!fh->file->isOpen()) { //file is not open
         return F_DISKERROR;
     }
-    if(offset>=fh->file->size()) {
+    if(offset>=fh->file->size()) { //offset exeeds filesize
         return F_INVALIDPARAM;
     }
 
-    if(fh->file->seek(offset)) {
-        fh->fpos = offset;
+    if(fh->file->seek(offset)) { //try to seek to desired offset
+        fh->fpos = offset; //update offset in FILE_HANDLE (for user)
         return F_OK;
-    } else {
+    } else { //seek failed
         return F_DISKERROR;
     }
 }
@@ -135,20 +140,20 @@ FILE_STATUS ll_filesystem_file_read(FILE_HANDLE* handle, uint8_t* buf, uint32_t
     if(handle==NULL || buf==NULL) {
         return F_INVALIDPARAM;
     }
-    QT_FILE_HANDLE* fh = static_cast<QT_FILE_HANDLE*>(handle);
-    if(!fh->file->isOpen()) {
+    QT_FILE_HANDLE* fh = static_cast<QT_FILE_HANDLE*>(handle); //cast pointer to QT_FILE_HANDLE
+    if(!fh->file->isOpen()) { //file is not open
         return F_DISKERROR;
     }
-    if(!fh->file->isReadable()) {
+    if(!fh->file->isReadable()) { //file is not readable
         return F_EACCESS;
     }
-    qint64 bytesRead = fh->file->read((char*)buf,size);
-    if(bytesRead<0) {
+    qint64 bytesRead = fh->file->read((char*)buf,size); //try to read desired amount of bytes
+    if(bytesRead<0) { //read failed
         return F_DISKERROR;
     }
-    fh->fpos+=bytesRead;
-    if(bytesRead!=size) {
-        return F_EOF;
+    fh->fpos+=bytesRead; //increase file position (for user)
+    if(bytesRead!=size) { //we got less bytes than expected
+        return F_EOF; //we reached the end of the file
     } else {
         return F_OK;
     }
@@ -158,24 +163,22 @@ FILE_STATUS ll_filesystem_file_write(FILE_HANDLE* handle, uint8_t* buf, uint32_t
     if(handle==NULL) {
         return F_INVALIDPARAM;
     }
-    QT_FILE_HANDLE* fh = static_cast<QT_FILE_HANDLE*>(handle);
-    if(!fh->file->isOpen()) {
+    QT_FILE_HANDLE* fh = static_cast<QT_FILE_HANDLE*>(handle); //cast pointer to QT_FILE_HANDLE
+    if(!fh->file->isOpen()) { //file is not open
         return F_DISKERROR;
     }
-    if(!fh->file->isWritable()) {
+    if(!fh->file->isWritable()) { //file is not writable
         return F_EACCESS;
     }
-    qint64 bytesWritten = fh->file->write((char*)buf,size);
-    if(bytesWritten<0) {
+    qint64 bytesWritten = fh->file->write((char*)buf,size); //try to write desired amount of bytes
+    if(bytesWritten<0) { //write failed
         return F_DISKERROR;
     }
-    fh->fpos+=bytesWritten;
-    if(bytesWritten!=size) {
-        return F_EOF;
+    fh->fpos+=bytesWritten; //increase file position (for user)
+    if(bytesWritten!=size) { //we wrote less bytes than expected
+        return F_EOF; //we reached the end of the file
     } else {
         return F_OK;
     }
 }
                                                                                                                                                                                
-
-
diff --git a/emulator/qt/ll_system.cpp b/emulator/qt/ll_system.cpp
index 8d087b5..68efd72 100644
--- a/emulator/qt/ll_system.cpp
+++ b/emulator/qt/ll_system.cpp
@@ -6,18 +6,18 @@ extern "C" {
 }
 
 bool ll_system_init() {
-    return true;
+    return true; //nothing to initialize here, apart from the stuff which is done in the main method.
 }
 
 void ll_system_delay(uint32_t msec) {
-        QThread::msleep(msec);
+        QThread::msleep(msec); //Let the app_process() Thread sleep
 }
 
 void ll_system_process() {
-        QApplication::processEvents();
-        QThread::msleep(1);
+        QApplication::processEvents(); //Process pending qt events
+        QThread::msleep(1); //Sleep for 1ms, to keep the cpu load down
 }
 
 void ll_system_toggle_led() {
-
+    //No led emulated :(
 }
diff --git a/emulator/qt/ll_tft.cpp b/emulator/qt/ll_tft.cpp
index ced8b52..5cc7093 100644
--- a/emulator/qt/ll_tft.cpp
+++ b/emulator/qt/ll_tft.cpp
@@ -1,5 +1,4 @@
 #include "mainwindow.h"
-#include <QDebug>
 
 extern "C" {
 #include "ll_tft.h"
@@ -8,13 +7,14 @@ extern "C" {
 MainWindow* mainwindow;
 
 bool ll_tft_init() {
-   qDebug() << "tft init done";
-   mainwindow = new MainWindow();
-   mainwindow->show();
+   mainwindow = new MainWindow(); //create the designed window
+   mainwindow->show(); //open it (non blocking)
    return true;
 
 }
 
+//the following functions redirect the call to the mainwindow, to a function with the same signature
+
 void ll_tft_draw_line(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2, uint16_t color) {
     mainwindow->draw_line(x1,y1,x2,y2,color);
 }
@@ -44,9 +44,11 @@ void ll_tft_draw_circle(uint16_t x, uint16_t y, uint16_t r, uint16_t color) {
 }
 
 uint8_t ll_tft_num_fonts() {
-    return 2;
+    return 2; //we have two fonts (see below)
 }
 
+//Helper function to get the QFont to the corresponding font number
+//Note: only return monospaced fonts!!!
 QFont get_font(uint8_t fontnum) {
     switch(fontnum) {
         case 0:
@@ -62,20 +64,20 @@ QFont get_font(uint8_t fontnum) {
 uint8_t ll_tft_font_height(uint8_t fontnum) {
     QFont f = get_font(fontnum);
     if(f == QFont()) return -1;
-    QFontMetrics m(f);
+    QFontMetrics m(f); //use font metcris object to calculate height of font
     return m.height();
 }
 
 uint8_t ll_tft_font_width(uint8_t fontnum) {
     QFont f = get_font(fontnum);
     if(f == QFont()) return -1;
-    QFontMetrics m(f);
+    QFontMetrics m(f); //use font metcris object to calculate width of font
     return m.averageCharWidth();
 }
 
 void ll_tft_draw_char(uint16_t x, uint16_t y, uint16_t color, uint16_t bgcolor, uint8_t font, char c) {
     QFont f = get_font(font);
-    if(f == QFont()) return;
+    if(f == QFont()) return; //if the font is the default-font, we want to abort.
     mainwindow->draw_char(x,y,color,bgcolor,f,c);
 }
 
diff --git a/emulator/qt/main.cpp b/emulator/qt/main.cpp
index dc67c83..96937c1 100644
--- a/emulator/qt/main.cpp
+++ b/emulator/qt/main.cpp
@@ -2,23 +2,23 @@
 #include <QtConcurrent/QtConcurrent>
 
 extern "C" {
-    //C Functions from the common folder
+    //Imported C Functions from the common folder
     void app_init(); //Initializes the app
     void app_process(); //Processes one eventloop of the app
 }
 
 void app_loop() {
-    while(!QApplication::closingDown()) {
-        app_process();
+    while(!QApplication::closingDown()) { //as long as the application is not terminating
+        app_process(); //let the application process it's events
     }
 }
 
 int main(int argc, char* argv[]) {
-    QApplication app(argc,argv);
-    app_init();
+    QApplication app(argc,argv); //Process qt-specific commandline arguments and create event loop
+    app_init(); //Let the application initialize it self
 
-    QtConcurrent::run(&app_loop);
-    return app.exec();
+    QtConcurrent::run(&app_loop); //Start a thread that executes app_loop
+    return app.exec(); //Run the event loop until the last window is closed.
 }
 
 
diff --git a/emulator/qt/mainwindow.cpp b/emulator/qt/mainwindow.cpp
index 0ed5eea..99b2ae2 100644
--- a/emulator/qt/mainwindow.cpp
+++ b/emulator/qt/mainwindow.cpp
@@ -13,16 +13,18 @@ extern "C" {
 #define DISPLAY_WIDTH 320
 #define DISPLAY_HEIGHT 240
 
+//function to calculate QColor out of a RGB565 16bit color
 QColor QColorFromRGB565(uint16_t color) {
-
+    //interpolate colors
     int R8 = (int) floor( (color>>(5+6)) * 255.0 / 31.0 + 0.5);
     int G8 = (int) floor( ((color>>5)&0x3F) * 255.0 / 63.0 + 0.5);
     int B8 = (int) floor( (color&0x1F) * 255.0 / 31.0 + 0.5);
     return QColor::fromRgb(R8,G8,B8);
 }
 
+//function to calculate QRgb out of a RGB565 16bit color
 QRgb QRgbFromRGB565(uint16_t color) {
-
+    //interpolate colors
     int R8 = (int) floor( (color>>(5+6)) * 255.0 / 31.0 + 0.5);
     int G8 = (int) floor( ((color>>5)&0x3F) * 255.0 / 63.0 + 0.5);
     int B8 = (int) floor( (color&0x1F) * 255.0 / 31.0 + 0.5);
@@ -32,156 +34,137 @@ QRgb QRgbFromRGB565(uint16_t color) {
 
 MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), image(DISPLAY_WIDTH,DISPLAY_HEIGHT, QImage::Format_RGB16), ui(new Ui::MainWindow){
     ui->setupUi(this);
-    image.fill(Qt::black);
-    currentScale = 1;
-    ui->widgetDisplay->setMouseTracking(true);
-    ui->widgetDisplay->installEventFilter(this);
+    image.fill(Qt::black); //clear display buffer
+    currentScale = 1; //start with scale factor 1
+    ui->widgetDisplay->setMouseTracking(true); //enable mouse move events, even when mouse is not pressed
+    ui->widgetDisplay->installEventFilter(this); //install event filter for "display" widget, so that we receive those events as well
 }
 
 void MainWindow::draw_line(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2, uint16_t color)
 {
-    //render_mutex.lock();
     QPainter painter(&(image));
     painter.setPen(QColorFromRGB565(color));
     painter.drawLine(x1,y1,x2,y2);
-    //render_mutex.unlock();
     update();
 }
 
 void MainWindow::draw_pixel(uint16_t x, uint16_t y, uint16_t color)
 {
-    //render_mutex.lock();
     image.setPixel(x,y,QRgbFromRGB565(color));
-    //render_mutex.unlock();
     update();
 }
 
 void MainWindow::clear(uint16_t color)
 {
-    //render_mutex.lock();
     image.fill(QColorFromRGB565(color));
-    //render_mutex.unlock();
     update();
 }
 
 void MainWindow::draw_rectangle(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2, uint16_t color)
 {
-    //render_mutex.lock();
     QPainter painter(&(image));
     painter.setPen(QColorFromRGB565(color));
-    painter.drawRect(qMin(x1,x2),qMin(y1,y2),abs((int)x2-(int)x1)+1,abs((int)y2-(int)y1)+1);
-    //render_mutex.unlock();
+    painter.drawRect(qMin(x1,x2),qMin(y1,y2),abs((int)x2-(int)x1),abs((int)y2-(int)y1));
     update();
 }
 
 void MainWindow::fill_rectangle(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2, uint16_t color)
 {
-    //render_mutex.lock();
     QPainter painter(&(image));
     painter.fillRect(qMin(x1,x2),qMin(y1,y2),abs((int)x2-(int)x1)+1,abs((int)y2-(int)y1)+1,QColorFromRGB565(color));
-    //render_mutex.unlock();
     update();
 }
 
 void MainWindow::draw_bitmap_unscaled(uint16_t x, uint16_t y, uint16_t width, uint16_t height, const uint16_t *dat)
 {
     //Creating a new image and access it directly is faster than setPixel
-    QImage img(width,height,QImage::Format_RGB32);
+    QImage img(width,height,QImage::Format_RGB32); //create a new image
 
-    for(int yi=0; yi<height; yi++) {
-        uint32_t* line = (uint32_t*)img.scanLine(yi);
-        for(int xi=0; xi<width; xi++) {
-            *line++=QRgbFromRGB565(dat[yi*width+xi]);
+    for(int yi=0; yi<height; yi++) { //for each line
+        uint32_t* line = (uint32_t*)img.scanLine(yi); //get the pointer to the imagedata of the current line
+        for(int xi=0; xi<width; xi++) { //for each column
+            *line++=QRgbFromRGB565(dat[yi*width+xi]); //set pixel
         }
     }
 
-    //render_mutex.lock();
     QPainter p(&image);
-    p.drawImage(x,y,img);
-    //render_mutex.unlock();
+    p.drawImage(x,y,img); //draw created image
     update();
 }
 
 void MainWindow::draw_circle(uint16_t x, uint16_t y, uint16_t r, uint16_t color)
 {
-    //render_mutex.lock();
     QPainter painter(&(image));
     painter.setPen(QColorFromRGB565(color));
     painter.drawEllipse(QPoint(x,y), r, r);
-    //render_mutex.unlock();
     update();
 }
 
 void MainWindow::draw_char(uint16_t x, uint16_t y, uint16_t color, uint16_t bgcolor, QFont font, char c)
 {
-    //render_mutex.lock();
     QPainter painter(&(image));
     painter.setFont(font);
 
-    if(bgcolor!=TRANSPARENT) {
+    if(bgcolor!=TRANSPARENT) { //background color is not transparent
             painter.setBackgroundMode(Qt::OpaqueMode);
-            painter.setBackground(QColorFromRGB565(bgcolor));
+            painter.setBackground(QColorFromRGB565(bgcolor)); //set text background
     }
 
-    painter.setPen(QColorFromRGB565(color));
+    painter.setPen(QColorFromRGB565(color)); //set fontcolor
     y+=QFontMetrics(font).ascent(); //use y pos as highest point of char, instead of baseline
-    painter.drawText(QPoint(x,y), QString(QChar(c)));
-    //render_mutex.unlock();
+    painter.drawText(QPoint(x,y), QString(QChar(c))); //draw char
     update();
 }
 
 void MainWindow::paintEvent(QPaintEvent *)
 {
-  //render_mutex.lock();
+  //this method is called whenever the window needs to be redrawn (or after update() is called)
   QPainter painter(this);
 
+  //Create a QRectF which represents the rectangle to draw the buffered image to
   QRectF imgRect (ui->widgetDisplay->geometry().topLeft(),QSizeF(DISPLAY_WIDTH*currentScale,DISPLAY_HEIGHT*currentScale));
 
-  painter.drawImage(imgRect,image);
-  painter.setPen(QPen(Qt::green,2));
-  painter.drawRect(imgRect.adjusted(-1,-1,1,1));
-
-
-  //render_mutex.unlock();
+  painter.drawImage(imgRect,image); //draw buffer
+  painter.setPen(QPen(Qt::green,2)); //set border color
+  painter.drawRect(imgRect.adjusted(-1,-1,1,1)); //draw border
 }
 
 void MainWindow::mousePressEvent(QMouseEvent *evt)
 {
-    //qDebug() << "down" << evt->pos();
+    //the mouse was pressed
     checkAndSendEvent(evt->pos(),true);
 }
 
 void MainWindow::mouseReleaseEvent(QMouseEvent *evt)
 {
-    //qDebug() << "up" << evt->pos();
+    //the mouse was released
     checkAndSendEvent(evt->pos(),false);
 }
 
 void MainWindow::mouseMoveEvent(QMouseEvent *evt)
 {
-   //qDebug() << "move" << evt->pos();
+    //the mouse was released
     checkAndSendEvent(evt->pos(),true);
 }
 
 
 bool MainWindow::eventFilter(QObject *obj, QEvent *evt)
 {
-   if(obj==ui->widgetDisplay) {
+   if(obj==ui->widgetDisplay) { //we received a redirect event from the target rectangle
         switch(evt->type()) {
-            case QEvent::MouseMove:
+            case QEvent::MouseMove: //it's a mouse move event
             {
-                QMouseEvent* mouseEvent = static_cast<QMouseEvent*>(evt);
-                QPoint p = (mouseEvent->pos()-QPoint(1,1))/currentScale;
-                if(p.x()<DISPLAY_WIDTH && p.y()<DISPLAY_HEIGHT) {
+                QMouseEvent* mouseEvent = static_cast<QMouseEvent*>(evt); //get mouse event
+                QPoint p = (mouseEvent->pos()-QPoint(1,1))/currentScale; //calculate correct corrdinates (undo scale)
+                if(p.x()<DISPLAY_WIDTH && p.y()<DISPLAY_HEIGHT) { //mouse position not out of bounds
+                    //set mouse position text
                     ui->txtMousePos->setText(QString("Mouse Position: (%1,%2)").arg(p.x()).arg(p.y()));
                 }
             }
             break;
-
             default: break;
         }
    }
-
      return false;
 }
 
@@ -193,18 +176,16 @@ MainWindow::~MainWindow()
 
 void MainWindow::checkAndSendEvent(QPoint pos, bool down)
 {
-    QPoint p = pos - ui->widgetDisplay->geometry().topLeft();
-    p/=currentScale;
-    if(p.x()<0 || p.y()<0 || p.x() >= DISPLAY_WIDTH || p.y() >= DISPLAY_HEIGHT) return;
+    QPoint p = pos - ui->widgetDisplay->geometry().topLeft(); //make coordinate relative to target area (0,0)
+    p/=currentScale; //undo scaling
+    if(p.x()<0 || p.y()<0 || p.x() >= DISPLAY_WIDTH || p.y() >= DISPLAY_HEIGHT) return; //abort if out of bounds
 
-    //qDebug() << down << p;
-
-    touch_add_raw_event(p.x(),p.y(),down?TOUCH_DOWN:TOUCH_UP);
+    touch_add_raw_event(p.x(),p.y(),down?TOUCH_DOWN:TOUCH_UP); //submit touch event to touch module (common)
 }
 
 
 void MainWindow::on_cboZoom_currentIndexChanged(int index)
 {
-    currentScale=index+1;
-    update();
+    currentScale=index+1; //zoom factor 1 is the 0th entry, zoom factor 2 is the 1st entry, zoom factor 3 is the 2nd entry
+    update(); //force redraw
 }
diff --git a/emulator/qt/mainwindow.h b/emulator/qt/mainwindow.h
index e9034e1..7c0f845 100644
--- a/emulator/qt/mainwindow.h
+++ b/emulator/qt/mainwindow.h
@@ -33,12 +33,11 @@ protected:
     ~MainWindow();
 
 private slots:
-     void on_cboZoom_currentIndexChanged(int index);
+     void on_cboZoom_currentIndexChanged(int index); //slot that is called when the zoomlevel changed
 
 private:
-    //QMutex render_mutex;
-    QImage image;
-    int currentScale;
+    QImage image; //Display buffer
+    int currentScale; //current scale factor
     void checkAndSendEvent(QPoint pos, bool down);
 
     Ui::MainWindow *ui;