diff --git a/CMakeLists.txt b/CMakeLists.txt
index d9fd70d..e355699 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,7 +22,7 @@ file(GLOB_RECURSE TESTS test/*.cpp)
 include_directories(src)
 include_directories(test)
 
-add_library(library ${SOURCES} ${HEADERS})
+add_library(library ${SOURCES} ${HEADERS} src/FontType.cpp)
 
 file(COPY "${CMAKE_SOURCE_DIR}/src/"
         DESTINATION "${CMAKE_SOURCE_DIR}/include"
diff --git a/src/Color.cpp b/src/Color.cpp
index b4bdb15..7d796fb 100644
--- a/src/Color.cpp
+++ b/src/Color.cpp
@@ -5,3 +5,28 @@ Color::Color(unsigned char red, unsigned char green, unsigned char blue)
     : red(red), green(green), blue(blue){
 
 }
+
+unsigned char Color::getRed() {
+    return red;
+}
+
+unsigned char Color::getGreen() {
+    return green;
+}
+
+unsigned char Color::getBlue() {
+    return blue;
+}
+
+void Color::setRed(unsigned char value) {
+    red = value;
+}
+
+void Color::setGreen(unsigned char value) {
+    green = value;
+}
+
+void Color::setBlue(unsigned char value) {
+    blue = value;
+}
+
diff --git a/src/Color.h b/src/Color.h
index b01a9c6..1191da4 100644
--- a/src/Color.h
+++ b/src/Color.h
@@ -17,6 +17,14 @@ private:
 public:
     Color(unsigned char red, unsigned char green, unsigned char blue);
 
+    unsigned char getRed();
+    unsigned char getGreen();
+    unsigned char getBlue();
+
+    void setRed(unsigned char value);
+    void setGreen(unsigned char value);
+    void setBlue(unsigned char value);
+
 };
 
 const static Color black = Color(0, 0, 0);
diff --git a/src/Font.cpp b/src/Font.cpp
deleted file mode 100644
index fa42d3b..0000000
--- a/src/Font.cpp
+++ /dev/null
@@ -1,22 +0,0 @@
-
-#include <string>
-#include <utility>
-#include "Font.h"
-
-Font::Font(std::string name, int height, int width) {
-    this->name = std::move(name);
-    this->height = height;
-    this->width = width;
-}
-
-std::string Font::getName() {
-    return name;
-}
-
-int Font::getHeight() {
-    return height;
-}
-
-int Font::getWidth() {
-    return width;
-}
diff --git a/src/FontType.cpp b/src/FontType.cpp
new file mode 100644
index 0000000..6ef7a54
--- /dev/null
+++ b/src/FontType.cpp
@@ -0,0 +1,20 @@
+#include "FontType.h"
+
+
+FontType::FontType(std::string name, int height, int width) {
+    this->name = std::move(name);
+    this->height = height;
+    this->width = width;
+}
+
+std::string FontType::getName() {
+    return name;
+}
+
+int FontType::getHeight() {
+    return height;
+}
+
+int FontType::getWidth() {
+    return width;
+}
diff --git a/src/Font.h b/src/FontType.h
similarity index 59%
rename from src/Font.h
rename to src/FontType.h
index 041c3c9..cf76bf4 100644
--- a/src/Font.h
+++ b/src/FontType.h
@@ -3,14 +3,16 @@
 #ifndef LIBRARY_FONT_H
 #define LIBRARY_FONT_H
 
-class Font {
+#include <string>
+
+class FontType {
 private:
     std::string name;
     int height;
     int width;
 
 public:
-    Font(std::string name, int height, int width);
+    FontType(std::string name, int height, int width);
     std::string getName();
     int getHeight();
     int getWidth();
@@ -18,6 +20,6 @@ public:
 };
 
 
-const static Font font_1 = Font("DummyFont", 10, 5);
+const static FontType font_1 = FontType("DummyFont", 10, 5);
 
 #endif
diff --git a/src/SharedMemoryAccess.cpp b/src/SharedMemoryAccess.cpp
index 8a4f4d0..0fd13dd 100644
--- a/src/SharedMemoryAccess.cpp
+++ b/src/SharedMemoryAccess.cpp
@@ -24,7 +24,9 @@
 int semId;
 struct sembuf semaphore;
 
-int initSemaphore (void) {
+std::vector<char> localSharedMemory;
+
+int initSemaphore () {
     /* Testen, ob das Semaphor bereits existiert */
     semId = semget (SEM_KEY, 0, IPC_PRIVATE);
     if (semId < 0) {
@@ -44,11 +46,11 @@ int initSemaphore (void) {
 }
 
 int semaphoreOperation (int op) {
-    semaphore.sem_op = op;
+    semaphore.sem_op = (short)op;
     semaphore.sem_flg = SEM_UNDO;
     if( semop (semId, &semaphore, 1) == -1) {
         perror(" semop ");
-        exit (EXIT_FAILURE);
+        return -1;
     }
     return 1;
 }
@@ -56,7 +58,7 @@ int semaphoreOperation (int op) {
 void writeSharedMemory(char *data, int size, int offset) {
     int shmId = shmget(impl.sharedMemoryKey, NULL, 0); // dont init just get the ID if already existing.
     if(shmId < 0 ) {
-        exit(EXIT_FAILURE);
+        return;
         /* we could return -1, not sure if it will be useful to continue after there is no shm allocated for any reason*/
     } else {
         char *shm_pointer = (char *) shmat(shmId, NULL, 0);
@@ -66,12 +68,34 @@ void writeSharedMemory(char *data, int size, int offset) {
     }
 }
 
-const char* getSharedMemory() {
+char* getSharedMemory() {
+    /*
     int shmId = shmget(impl.sharedMemoryKey, NULL, 0);
     if(shmId < 0) {
-        exit(EXIT_FAILURE);
-        /* we could return -1, not sure if it will be useful to continue after there is no shm allocated for any reason*/
+        return nullptr;
+        // we could return -1, not sure if it will be useful to continue after there is no shm allocated for any reason
     } else {
         return (char *) shmat(shmId, NULL, 0);
     }
-}
\ No newline at end of file
+    */
+
+    //using a local buffer for shared memory testing
+    if(localSharedMemory.empty()){
+        initSemaphore();
+        localSharedMemory.resize(impl.sharedMemorySize * 1024);
+    }
+
+    return &localSharedMemory[0];
+}
+
+int getSharedMemorySize() {
+    return impl.sharedMemorySize;
+}
+
+void lockSharedMemory() {
+    semaphoreOperation(LOCK);
+}
+
+void unlockSharedMemory() {
+    semaphoreOperation(UNLOCK);
+}
diff --git a/src/SharedMemoryAccess.h b/src/SharedMemoryAccess.h
index cdb4c45..949307b 100644
--- a/src/SharedMemoryAccess.h
+++ b/src/SharedMemoryAccess.h
@@ -7,10 +7,10 @@
 
 
 /**
- * only to read the shared memory
+ * use lock and unlock when writing
  * @return pointer to the shared memory
  */
-const char *getSharedMemory();
+char *getSharedMemory();
 
 /**
  *
@@ -18,6 +18,10 @@ const char *getSharedMemory();
  */
 int getSharedMemorySize();
 
+void lockSharedMemory();
+
+void unlockSharedMemory();
+
 /**
  *
  * @param data poiter to data
diff --git a/src/internal.cpp b/src/internal.cpp
index feba66a..4fb1a26 100644
--- a/src/internal.cpp
+++ b/src/internal.cpp
@@ -1,9 +1,10 @@
 #include "internal.h"
+#include "SharedMemoryAccess.h"
+#include "vkvm.h"
+
 #include <sys/shm.h>
 #include <csignal>
 
-#include "SharedMemoryAccess.h"
-
 Impl impl;
 
 void sendSignal(pid_t pid, int signalNumber) {
@@ -15,7 +16,22 @@ void onSignal(int signalNumber, void(*callback)(int)) {
 }
 
 InterruptEntry *getInterrupTable(){
-    return (InterruptEntry*)((char*)getSharedMemory() + sizeof(Registers) + 1024/*reserved*/);
+    return (InterruptEntry*)(getSharedMemory() + sizeof(Registers) + impl.reservedSize);
+}
+
+Registers *getRegisters(){
+    return (Registers*)getSharedMemory();
+}
+
+char *getTextArea(){
+    return ((getSharedMemory() + sizeof(Registers) + impl.reservedSize) +
+    sizeof(InterruptEntry) * impl.interruptEntyCount);
+}
+
+char *getPixelArea(){
+    return (((getSharedMemory() + sizeof(Registers) + impl.reservedSize) +
+    sizeof(InterruptEntry) * impl.interruptEntyCount) +
+    getCharactersPerRow() *  getCharactersPerColumn());
 }
 
 bool callEvent(EventType type) {
@@ -27,21 +43,30 @@ bool callEvent(EventType type) {
 }
 
 void setLayoutVersion(LayoutVersion newValue) {
-
+    lockSharedMemory();
+    getRegisters()->layout_version = newValue;
+    unlockSharedMemory();
 }
 
-void setCharactersPerLine(int newValue) {
-
+void setCharactersPerColumn(int newValue) {
+    lockSharedMemory();
+    getRegisters()->characters_per_column = newValue;
+    unlockSharedMemory();
 }
 
 void setCharactersPerRow(int newValue) {
-
+    lockSharedMemory();
+    getRegisters()->characters_per_row = newValue;
+    unlockSharedMemory();
 }
 
 void setMousePosition(int x, int y) {
-
+    lockSharedMemory();
+    getRegisters()->mouse_pos_x = x;
+    getRegisters()->mouse_pos_y = y;
+    unlockSharedMemory();
 }
 
 void buttonPressed(KeyCode keyCode) {
-
+    //TODO
 }
diff --git a/src/internal.h b/src/internal.h
index a6f273a..098575a 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -50,6 +50,7 @@ struct Impl {
     key_t sharedMemoryKey;
     int sharedMemorySize;
     int interruptEntyCount = 64;
+    int reservedSize = 1024;
     std::vector<std::function<void()>> eventTable;
 };
 
@@ -70,6 +71,10 @@ void onSignal(int signalNumber, void(*callback)(int));
 
 
 InterruptEntry *getInterrupTable();
+Registers *getRegisters();
+char *getTextArea();
+char *getPixelArea();
+
 
 /**
  * set layout version.
@@ -78,10 +83,10 @@ InterruptEntry *getInterrupTable();
 void setLayoutVersion(LayoutVersion newValue);
 
 /**
- * set characters per line for current font.
- * @param newValue characters per line.
+ * set characters per column for current font.
+ * @param newValue characters per column.
  */
-void setCharactersPerLine(int newValue);
+void setCharactersPerColumn(int newValue);
 
 /**
  * set characters per row for current font.
diff --git a/src/vkvm.cpp b/src/vkvm.cpp
index 72d999b..9ea06b3 100644
--- a/src/vkvm.cpp
+++ b/src/vkvm.cpp
@@ -1,29 +1,36 @@
 #include "vkvm.h"
 #include "internal.h"
+#include "SharedMemoryAccess.h"
+
 #include <unistd.h>
 #include <csignal>
 
 void initialize(int pid) {
     impl.sharedMemoryPid = pid;
     impl.sharedMemoryKey = 12345;
-    impl.sharedMemorySize = 0;
-}
+    impl.sharedMemorySize = 8000;
 
-bool setPixel(int x, int y, Color color) {
-    return true;
-}
-
-Color getPixel(int x, int y) {
-    return {255, 0, 0};
+    //set default values
+    setCharactersPerRow(60);
+    setCharactersPerColumn(20);
+    setHeight(600);
+    setWidth(800);
+    setMousePosition(42,42);
+    setBackgroundColor(Color(200,50,20));
+    setForegroundColor(Color(20,200,50));
+    setMode(GraphicMode::TrueColor);
+    setRedrawInterval(20);
+    setTimerInterruptInterval(10);
 }
 
 bool registerEvent(EventType type, std::function<void()> handler) {
     int signum = SIGUSR1 + impl.eventTable.size();
-
     auto ivt = getInterrupTable();
+
+    lockSharedMemory();
+
     ivt[type].pid = getpid();
     ivt[type].signum = signum;
-
     impl.eventTable.push_back(handler);
 
     onSignal(signum, [](int sig){
@@ -34,101 +41,149 @@ bool registerEvent(EventType type, std::function<void()> handler) {
         }
     });
 
+    unlockSharedMemory();
+
     return true;
 }
 
-bool setText(std::string text) {
+bool setPixel(int x, int y, Color color) {
+    char *ptr = getPixelArea() + (y * getWidth() + x) * 3;
+    ptr[0] = color.getRed();
+    ptr[1] = color.getGreen();
+    ptr[2] = color.getBlue();
     return false;
 }
 
+Color getPixel(int x, int y) {
+    //TODO: other than RGB colores
+    //only RGB colores for now
+    unsigned char *ptr = (unsigned char *)getPixelArea() + (y * getWidth() + x) * 3;
+    return Color(ptr[0], ptr[1], ptr[2]);
+}
+
+bool setText(std::string text) {
+    lockSharedMemory();
+    char *ptr = getTextArea();
+    for(int i = 0; i < text.size();i++){
+        if(i >= getCharactersPerColumn() * getCharactersPerRow()){
+            break;
+        }
+        ptr[i] = text[i];
+    }
+    if(text.size() < getCharactersPerColumn() * getCharactersPerRow()){
+        ptr[text.size()] = '\0';
+    }
+    unlockSharedMemory();
+    return true;
+}
+
 std::string getText() {
-    return "Hallo Welt";
+    return std::string (getTextArea());
 }
 
 LayoutVersion getLayoutVersion() {
-    return V1;
+    return (LayoutVersion)getRegisters()->layout_version;
 }
 
 void reset() {
-
+    //TODO
 }
 
 int getWidth() {
-    return 360;
+    return getRegisters()->width_pixels;
 }
 
 void setWidth(int newValue) {
-
+    lockSharedMemory();
+    getRegisters()->width_pixels = newValue;
+    unlockSharedMemory();
 }
 
 int getHeight() {
-    return 360;
+    return getRegisters()->height_pixels;
 }
 
 void setHeight(int newValue) {
-
+    lockSharedMemory();
+    getRegisters()->height_pixels = newValue;
+    unlockSharedMemory();
 }
 
 GraphicMode getMode() {
-    return TrueColor;
+    return getRegisters()->graphicMode;
 }
 
 void setMode(GraphicMode newValue) {
-
+    lockSharedMemory();
+    getRegisters()->graphicMode = newValue;
+    unlockSharedMemory();
 }
 
 int getRedrawInterval() {
-    return 10;
+    return getRegisters()->autoRedrawInterval;
 }
 
 void setRedrawInterval(int newValue) {
-
+    lockSharedMemory();
+    getRegisters()->autoRedrawInterval = newValue;
+    unlockSharedMemory();
 }
 
 int getTimerInterruptInterval() {
-    return 5;
+    return getRegisters()->timerInterruptInterval;
 }
 
 void setTimerInterruptInterval(int newValue) {
-
+    lockSharedMemory();
+    getRegisters()->timerInterruptInterval = newValue;
+    unlockSharedMemory();
 }
 
 Color getBackgroundColor() {
-    return black;
+    return getRegisters()->background_color;
 }
 
 void setBackgroundColor(Color newValue) {
-
+    lockSharedMemory();
+    getRegisters()->background_color = newValue;
+    unlockSharedMemory();
 }
 
 Color getForegroundColor() {
-    return white;
+    return getRegisters()->foreground_color;
 }
 
 void setForegroundColor(Color newValue) {
-
+    lockSharedMemory();
+    getRegisters()->foreground_color = newValue;
+    unlockSharedMemory();
 }
 
 int getCharactersPerRow() {
-    return 5;
+    return getRegisters()->characters_per_row;
 }
 
 int getCharactersPerColumn() {
-    return 5;
+    return getRegisters()->characters_per_column;
 }
 
-Font getFont() {
+FontType getFont() {
+    //TODO
     return font_1;
 }
 
-void setFont(Font newValue) {
-
+void setFont(FontType newValue) {
+    //TODO
+    lockSharedMemory();
+    getRegisters()->textMode_font = 0;
+    unlockSharedMemory();
 }
 
 std::pair<int, int> getMousePosition() {
-    return {10, 50};
+    return {getRegisters()->mouse_pos_x, getRegisters()->mouse_pos_y};
 }
 
 KeyCode getLastPressedKey() {
-    return KeyCode(50);
+    //TODO
+    return KeyCode(0);
 }
diff --git a/src/vkvm.h b/src/vkvm.h
index a95731f..180a1d5 100644
--- a/src/vkvm.h
+++ b/src/vkvm.h
@@ -6,7 +6,7 @@
 #include "Color.h"
 #include "EventType.h"
 #include "GraphicMode.h"
-#include "Font.h"
+#include "FontType.h"
 #include "KeyCode.h"
 #include "LayoutVersion.h"
 
@@ -178,13 +178,13 @@ int getCharactersPerColumn();
  * get currently used font in text mode.
  * @return currently used font.
  */
-Font getFont();
+FontType getFont();
 
 /**
  * set text mode font.
  * @param newValue new text mode font.
  */
-void setFont(Font newValue);
+void setFont(FontType newValue);
 
 /**
  * get current mouse position