diff --git a/libs/microbit-bluetooth/bluetooth.cpp b/libs/microbit-bluetooth/bluetooth.cpp
index da9b4eeb..890f2f2c 100644
--- a/libs/microbit-bluetooth/bluetooth.cpp
+++ b/libs/microbit-bluetooth/bluetooth.cpp
@@ -101,38 +101,18 @@ namespace bluetooth {
         uart = new MicroBitUARTService(*uBit.ble, 61, 60);
     }
     
-    /**
-    *  Writes to the Bluetooth UART service buffer. From there the data is transmitted over Bluetooth to a connected device.
-    */
-    //% help=bluetooth/uart-write
-    //% blockId=bluetooth_uart_write block="bluetooth uart write %data" blockGap=8
-    //% parts="bluetooth"
+    //%
     void uartWrite(StringData *data) {
         startUartService();
     	uart->send(ManagedString(data));
     }    
 
-    /**
-    *  Reads from the Bluetooth UART service buffer, returning its contents when the specified delimiter character is encountered.
-    */
-    //% help=bluetooth/uart-read
-    //% blockId=bluetooth_uart_read block="bluetooth uart read %del=bluetooth_uart_delimiter_conv" blockGap=8
-    //% parts="bluetooth"
+    //%
     StringData* uartRead(StringData *del) {
         startUartService();
         return uart->readUntil(ManagedString(del)).leakData();
     }    
 
-    /**
-    * Returns the delimiter corresponding string
-    */
-    //% blockId="bluetooth_uart_delimiter_conv" block="%del"
-    //% weight=1
-    //% parts="bluetooth"
-    StringData* delimiters(Delimiters del) {  
-        ManagedString c("\n\n,$:.#"[max(0, min(6, (int)del))]);
-        return c.leakData();
-    }
     /**
      * Register code to run when the micro:bit is connected to over Bluetooth
      * @param body Code to run when a Bluetooth connection is established
diff --git a/libs/microbit-bluetooth/bluetooth.ts b/libs/microbit-bluetooth/bluetooth.ts
new file mode 100644
index 00000000..05144086
--- /dev/null
+++ b/libs/microbit-bluetooth/bluetooth.ts
@@ -0,0 +1,43 @@
+namespace bluetooth {
+    /**
+     * Returns the delimiter corresponding string
+     */
+    //% blockId="bluetooth_uart_delimiter_conv" block="%del"
+    //% weight=1 parts="bluetooth"
+    export function delimiters(del: Delimiters): string {
+        // even though it might not look like, this is more
+        // (memory) efficient than the C++ implementation, because the
+        // strings are statically allocated and take no RAM 
+        switch (del) {
+            case Delimiters.NewLine: return "\n"
+            case Delimiters.Comma: return ","
+            case Delimiters.Dollar: return "$"
+            case Delimiters.Colon: return ":"
+            case Delimiters.Fullstop: return "."
+            case Delimiters.Hash: return "#"
+            default: return "\n"
+        }
+    }
+
+    /**
+    *  Writes to the Bluetooth UART service buffer. From there the data is transmitted over Bluetooth to a connected device.
+    */
+    //% help=bluetooth/uart-write
+    //% blockId=bluetooth_uart_write block="bluetooth uart write %data" blockGap=8
+    //% parts="bluetooth" shim=bluetooth::uartWrite
+    export function uartWrite(data: string): void {
+        // dummy implementation for simulator
+        console.log("UART Write: " + data)
+    }
+
+    /**
+     *  Reads from the Bluetooth UART service buffer, returning its contents when the specified delimiter character is encountered.
+     */
+    //% help=bluetooth/uart-read
+    //% blockId=bluetooth_uart_read block="bluetooth uart read %del=bluetooth_uart_delimiter_conv" blockGap=8
+    //% parts="bluetooth" shim=bluetooth::uartRead
+    export function uartRead(del: string): string {
+        // dummy implementation for simulator
+        return "???"
+    }
+}
diff --git a/libs/microbit-bluetooth/pxt.json b/libs/microbit-bluetooth/pxt.json
index bfa289f0..e486d262 100644
--- a/libs/microbit-bluetooth/pxt.json
+++ b/libs/microbit-bluetooth/pxt.json
@@ -5,6 +5,7 @@
         "README.md",
         "enums.d.ts",
         "shims.d.ts",
+        "bluetooth.ts",
         "bluetooth.cpp"
     ],
     "public": true,
diff --git a/libs/microbit-bluetooth/shims.d.ts b/libs/microbit-bluetooth/shims.d.ts
index f76076f1..31c8e34b 100644
--- a/libs/microbit-bluetooth/shims.d.ts
+++ b/libs/microbit-bluetooth/shims.d.ts
@@ -63,30 +63,6 @@ declare namespace bluetooth {
     //% parts="bluetooth" shim=bluetooth::startUartService
     function startUartService(): void;
 
-    /**
-     *  Writes to the Bluetooth UART service buffer. From there the data is transmitted over Bluetooth to a connected device.
-     */
-    //% help=bluetooth/uart-write
-    //% blockId=bluetooth_uart_write block="bluetooth uart write %data" blockGap=8
-    //% parts="bluetooth" shim=bluetooth::uartWrite
-    function uartWrite(data: string): void;
-
-    /**
-     *  Reads from the Bluetooth UART service buffer, returning its contents when the specified delimiter character is encountered.
-     */
-    //% help=bluetooth/uart-read
-    //% blockId=bluetooth_uart_read block="bluetooth uart read %del=bluetooth_uart_delimiter_conv" blockGap=8
-    //% parts="bluetooth" shim=bluetooth::uartRead
-    function uartRead(del: string): string;
-
-    /**
-     * Returns the delimiter corresponding string
-     */
-    //% blockId="bluetooth_uart_delimiter_conv" block="%del"
-    //% weight=1
-    //% parts="bluetooth" shim=bluetooth::delimiters
-    function delimiters(del: Delimiters): string;
-
     /**
      * Register code to run when the micro:bit is connected to over Bluetooth
      * @param body Code to run when a Bluetooth connection is established