diff --git a/simulation/include/Adafruit_GFX.h b/simulation/include/Adafruit_GFX.h
index c08075c..3d97b52 100644
--- a/simulation/include/Adafruit_GFX.h
+++ b/simulation/include/Adafruit_GFX.h
@@ -16,6 +16,7 @@ public: // Exposed simulation variables...
   bool dimmed_;
   bool enabled_;
   bool inverted_;
+  bool dirty_;
 
  public:
 
diff --git a/simulation/src/Adafruit_SSD1306_sim.cpp b/simulation/src/Adafruit_SSD1306_sim.cpp
index 02eb17c..5621833 100644
--- a/simulation/src/Adafruit_SSD1306_sim.cpp
+++ b/simulation/src/Adafruit_SSD1306_sim.cpp
@@ -611,8 +611,7 @@ uint8_t *Adafruit_SSD1306::getBuffer(void) {
             of graphics commands, as best needed by one's own application.
 */
 void Adafruit_SSD1306::display(void) {
-
-  // TODO: Update SDL surface with content of `buffer`
+  dirty_ = true;
 
 }
 
@@ -723,6 +722,7 @@ void Adafruit_SSD1306::ssd1306_command(uint8_t cmd)
       break;
     case SSD1306_DISPLAYON:
       enabled_ = true;
+      dirty_ = true;
       break;
 
     default: break;
diff --git a/simulation/src/nuevisim.cpp b/simulation/src/nuevisim.cpp
index 7a4d29b..9a62290 100644
--- a/simulation/src/nuevisim.cpp
+++ b/simulation/src/nuevisim.cpp
@@ -47,8 +47,6 @@ void _reboot_Teensyduino_()
     setup();
 }
 
-extern void menu(void);
-extern void initDisplay(void);
 extern void breath();
 extern int noteValueCheck(int);
 extern unsigned int breathCurve(unsigned int);
@@ -189,7 +187,6 @@ static void doGlobalsWindow()
 {
     if( ImGui::Begin("Globals" ) ) {
 
-
         if(ImGui::TreeNode("Sensor limits") )
         {
             ImGui::LabelText("Breath Thr", "%d", breathThrVal);
@@ -376,13 +373,15 @@ static uint8_t displayBuffer[128*128];
 
 static void GetDisplay()
 {
-    SDL_memset( displayBuffer, 0, (128*128));
-
-    if(display.enabled_) {
+    if(!display.enabled_) {
+        SDL_memset( displayBuffer, 0, (128*128));
+    } else if(display.dirty_) {
         uint8_t fg = 255;
         uint8_t bg = 0;
 
-        if( display.dimmed_) fg = 127;
+        display.dirty_ = false;
+
+        if( display.dimmed_ ) fg = 0b01001001;
         if( display.inverted_ ) { uint8_t tmp = fg; fg = bg; bg = tmp; }
 
         for(int y = 0 ; y < 64; ++y) {