diff --git a/libs/cpp-test/hello.ts b/libs/cpp-test/hello.ts
index 6f4776d1..4b8b9240 100644
--- a/libs/cpp-test/hello.ts
+++ b/libs/cpp-test/hello.ts
@@ -1,7 +1,3 @@
-//% shim=foo::bar
-function test() {
-}
-
 basic.plotLeds(`
 # # . # #
 . . # . .
@@ -10,4 +6,4 @@ basic.plotLeds(`
 . # # # .
 `);
 basic.pause(300);
-test();
+foo.bar();
diff --git a/libs/cpp-test/support.cpp b/libs/cpp-test/support.cpp
index 1474159a..89d523f9 100644
--- a/libs/cpp-test/support.cpp
+++ b/libs/cpp-test/support.cpp
@@ -1,6 +1,10 @@
+#include "BitVM.h"
+#include "MicroBitTouchDevelop.h"
+
 namespace foo {
-  GLUE void bar()
+  //%
+  void bar()
   {
-    micro_bit::scrollNumber(108108, 50);
+    touch_develop::micro_bit::scrollNumber(108108, 50);
   }
 }
diff --git a/libs/microbit/basic.ts b/libs/microbit/basic.cpp
similarity index 54%
rename from libs/microbit/basic.ts
rename to libs/microbit/basic.cpp
index 5c94e097..f2b999a4 100644
--- a/libs/microbit/basic.ts
+++ b/libs/microbit/basic.cpp
@@ -1,3 +1,8 @@
+#include "BitVM.h"
+
+
+typedef uint32_t ImageLiteral;
+
 /**
  * Provides access to basic micro:bit functionality.
  */
@@ -10,10 +15,19 @@ namespace basic {
      */
     //% help=basic/show-number
     //% weight=96
-    //% shim=micro_bit::scrollNumber
     //% blockId=device_show_number block="show|number %number" blockGap=8 icon="\uf1ec"
     //% async
-    export function showNumber(value: number, interval: number = 150): void { }
+    void showNumber(int value, int interval = 150) { 
+      if (interval < 0)
+        return;
+
+      ManagedString t(value);
+      if (value < 0 || value >= 10) {
+        uBit.display.scroll(t, interval);
+      } else {
+        uBit.display.print(t.charAt(0), interval * 5);
+      }
+    }
 
     /**
      * Draws an image on the LED screen.
@@ -22,11 +36,12 @@ namespace basic {
      */
     //% help=basic/show-leds 
     //% weight=95 blockGap=8
-    //% shim=micro_bit::showLeds 
     //% imageLiteral=1 async
     //% blockId=device_show_leds
     //% block="show leds" icon="\uf00a"
-    export function showLeds(leds: string, interval: number = 400): void { }
+    void showLeds(ImageLiteral leds, int interval = 400) {
+      uBit.display.print(MicroBitImage(getbytes(leds)), 0, 0, 0, delay);
+    }
 
     /**
      * Display text on the display, one character at a time. If the string fits on the screen (i.e. is one letter), does not scroll.
@@ -35,19 +50,32 @@ namespace basic {
      */
     //% help=basic/show-string 
     //% weight=87 blockGap=8
-    //% shim=micro_bit::scrollString async 
     //% block="show|string %text" icon="\uf031" 
     //% async
     //% blockId=device_print_message
-    export function showString(text: string, interval: number = 150): void { }
+    void showString(StringData *text, int interval = 150) {
+      if (interval < 0)
+        return;
+      ManagedString s(text);
+      int l = s.length();
+      if (l == 0) {
+        uBit.display.clear();
+        uBit.sleep(interval * 5);
+      } else if (l > 1) {
+        uBit.display.scroll(s, interval);
+      } else {
+        uBit.display.print(s.charAt(0), interval * 5);
+      }
+    }
 
     /**
      * Turn off all LEDs
      */
     //% help=basic/clear-screen weight=79
-    //% shim=micro_bit::clearScreen
     //% blockId=device_clear_display block="clear screen" icon="\uf12d"
-    export function clearScreen(): void { }
+    void clearScreen() {
+      uBit.display.image.clear();
+    }
 
     /**
      * Shows a sequence of LED screens as an animation.
@@ -55,29 +83,48 @@ namespace basic {
      * @param interval TODO
      */
     //% help=basic/show-animation shim=micro_bit::showAnimation imageLiteral=1 async
-    export function showAnimation(leds: string, interval: number = 400): void { }
+    void showAnimation(ImageLiteral leds, int interval = 400) {
+      uBit.display.animate(MicroBitImage(getbytes(leds)), interval, 5, 0);
+    }
 
     /**
      * Draws an image on the LED screen.
      * @param leds TODO
      */
-    //% help=basic/plot-leds weight=80 shim=micro_bit::plotLeds imageLiteral=1
-    export function plotLeds(leds: string): void { }
+    //% help=basic/plot-leds weight=80 shim=micro_bit::plotLeds
+    void plotLeds(ImageLiteral leds) {
+      MicroBitImage i(getbytes(leds));
+      uBit.display.print(i, 0, 0, 0, 0);
+    }
+
+    void forever_stub(void *a) {
+      while (true) {
+        action::run((Action)a);
+        micro_bit::pause(20);
+      }
+    }
 
     /**
      * Repeats the code forever in the background. On each iteration, allows other codes to run.
      * @param body TODO
      */
     //% help=basic/forever weight=55 blockGap=8
-    //% blockId=device_forever block="forever" icon="\uf01e" shim=micro_bit::forever
-    export function forever(body: () => void): void { }
+    //% blockId=device_forever block="forever" icon="\uf01e"
+    void forever(Action a) {
+      if (a != 0) {
+        incr(a);
+        create_fiber(forever_stub, (void*)a);
+      }
+    }
 
     /**
      * Pause for the specified time in milliseconds
      * @param ms how long to pause for, eg: 100, 200, 500, 1000, 2000
      */
     //% help=basic/pause weight=54
-    //% shim=micro_bit::pause async block="pause (ms) %pause"
+    //% async block="pause (ms) %pause"
     //% blockId=device_pause icon="\uf110"
-    export function pause(ms: number): void { }
+    void pause(int ms) {
+      uBit.sleep(ms);
+    }
 }
diff --git a/libs/microbit/control.cpp b/libs/microbit/control.cpp
new file mode 100644
index 00000000..167f3820
--- /dev/null
+++ b/libs/microbit/control.cpp
@@ -0,0 +1,30 @@
+#include "BitVM.h"
+
+namespace control {
+    void fiberDone(void *a)
+    {
+      decr((Action)a);
+      release_fiber();
+    }
+
+    /**
+     * Schedules code that run in the background.
+     */
+    //% help=control/in-background
+    //% blockId="control_in_background" block="run in background" blockGap=8
+    void inBackground(Action a) {
+      if (a != 0) {
+        incr(a);
+        create_fiber((void(*)(void*))action::run, (void*)a, fiberDone);
+      }
+    }
+
+    /**
+     * Resets the BBC micro:bit.
+     */
+    //% weight=30 async help=control/reset
+    //% blockId="control_reset" block="reset"
+    void reset() { 
+      uBit.reset(); 
+    }
+}
diff --git a/libs/microbit/control.ts b/libs/microbit/control.ts
index a1d358d1..f8112492 100644
--- a/libs/microbit/control.ts
+++ b/libs/microbit/control.ts
@@ -192,27 +192,29 @@ enum EventBusValue {
 
 //% weight=1 color="#333333"
 namespace control {
-    /**
-     * Schedules code that run in the background.
-     */
-    //% help=control/in-background shim=micro_bit::runInBackground
-    //% blockId="control_in_background" block="run in background" blockGap=8
-    export function inBackground(body: Action): void { }
 
     /**
-     * Resets the BBC micro:bit.
+     * Returns the value of a C++ runtime constant
      */
-    //% weight=30 shim=uBit.reset async help=control/reset
-    //% blockId="control_reset" block="reset"
-    export function reset(): void { }
+    //% weight=19 weight=19 blockId="control_event_source" block="%id"
+    export function eventSource(id: EventBusSource) : number {
+        return id;
+    }
+    /**
+     * Returns the value of a C++ runtime constant
+     */
+    //% weight=19 weight=19 blockId="control_event_value" block="%id"
+    export function eventValue(id: EventBusValue) : number {
+        return id;
+    }
 
     /**
      * Raises an event in the event bus.
-     @param src ID of the MicroBit Component that generated the event e.g. MICROBIT_ID_BUTTON_A.
-     @param value Component specific code indicating the cause of the event.
-     @param mode optional definition of how the event should be processed after construction (default is CREATE_AND_QUEUE).
-    */
-    // shim=micro_bit::busRaiseEvent
+     * @param src ID of the MicroBit Component that generated the event e.g. MICROBIT_ID_BUTTON_A.
+     * @param value Component specific code indicating the cause of the event.
+     * @param mode optional definition of how the event should be processed after construction (default is CREATE_AND_QUEUE).
+     */
+    //% shim=micro_bit::busRaiseEvent
     //% weight=21 blockGap=12 blockId="control_raise_event" block="raise event|from source %src=control_event_source|with value %value=control_event_value" blockExternalInputs=1
     export function raiseEvent(src: number, value: number, mode: EventCreationMode = EventCreationMode.CreateAndQueue): void { }
 
@@ -223,19 +225,4 @@ namespace control {
     //% weight=20 blockGap=8 blockId="control_on_event" block="on event|from %src=control_event_source|with value %value=control_event_value" 
     //% blockExternalInputs=1 blockStatement=1
     export function onEvent(src: number, value: number, handler: Action): void { }
-
-    /**
-     * Returns the value of a C++ runtime constant
-     */
-    //% weight=19 shimw=TD_ID weight=19 blockId="control_event_source" block="%id"
-    export function eventSource(id: EventBusSource) : number {
-        return 0;
-    }
-    /**
-     * Returns the value of a C++ runtime constant
-     */
-    //% weight=19 shimw=TD_ID weight=19 blockId="control_event_value" block="%id"
-    export function eventValue(id: EventBusValue) : number {
-        return 0;
-    }
 }
diff --git a/libs/microbit/kind.json b/libs/microbit/kind.json
index 6cd6bc30..6f827ac1 100644
--- a/libs/microbit/kind.json
+++ b/libs/microbit/kind.json
@@ -7,9 +7,10 @@
         "core.d.ts",
         "mbit.ts",
         "images.ts",
-        "basic.ts",
+        "basic.cpp",
         "input.ts",
         "control.ts",
+        "control.cpp",
         "game.ts",
         "led.ts",
         "music.ts",