diff --git a/libs/microbit/core.d.ts b/libs/microbit/core.d.ts
deleted file mode 100644
index 0f7f7f96..00000000
--- a/libs/microbit/core.d.ts
+++ /dev/null
@@ -1,181 +0,0 @@
-///
-
-interface Array {
- /**
- * Gets or sets the length of the array. This is a number one higher than the highest element defined in an array.
- */
- //% shim=Array_::length
- length: number;
-
- /**
- * Appends new elements to an array.
- * @param items New elements of the Array.
- */
- //% shim=Array_::push
- push(item: T): void;
-
- /**
- * Removes the last element from an array and returns it.
- */
- //% helper=arrayPop
- pop(): T;
-
- /**
- * Reverses the elements in an Array.
- */
- //% helper=arrayReverse
- reverse(): void;
-
- /**
- * Removes the first element from an array and returns it.
- */
- //% helper=arrayShift
- shift(): T;
-
- /**
- * Returns a section of an array.
- * @param start The beginning of the specified portion of the array.
- * @param end The end of the specified portion of the array.
- */
- //% helper=arraySlice
- slice(start: number, end: number): T[];
-
- /** Removes the first occurence of an object. Returns true if removed. */
- //% shim=Array_::removeElement
- removeElement(element:T) : boolean;
-
- /** Removes the object at position index. */
- //% shim=Array_::removeAt
- removeAt(idx:number) : void;
-
-
- /**
- * Removes elements from an array.
- * @param start The zero-based location in the array from which to start removing elements.
- * @param deleteCount The number of elements to remove.
- */
- //% helper=arraySplice
- splice(start: number, deleteCount: number): void;
-
- /**
- * Inserts new elements at the start of an array.
- * @param items Elements to insert at the start of the Array.
- */
- //% helper=arrayUnshift
- unshift(item:T): void;
-
- /**
- * Returns the index of the first occurrence of a value in an array.
- * @param searchElement The value to locate in the array.
- * @param fromIndex The array index at which to begin the search. If fromIndex is omitted, the search starts at index 0.
- */
- //% shim=Array_::indexOf
- indexOf(searchElement: T, fromIndex?: number): number;
-
-
- [n: number]: T;
-}
-
-declare interface String {
- /**
- * Returns the character at the specified index.
- * @param pos The zero-based index of the desired character.
- */
- //% shim=String_::charAt
- charAt(pos: number): string;
-
- /**
- * Returns the Unicode value of the character at the specified location.
- * @param index The zero-based index of the desired character. If there is no character at the specified index, NaN is returned.
- */
- //% shim=String_::charCodeAt
- charCodeAt(index: number): number;
-
- /**
- * Returns a string that contains the concatenation of two or more strings.
- * @param other The string to append to the end of the string.
- */
- //% shim=String_::concat
- concat(other: string): string;
-
- /**
- * Determines whether relative order of two strings (in ASCII encoding).
- * @param that String to compare to target string
- */
- //% shim=String_::compare
- compare(that: string): number;
-
- /** Returns the length of a String object. */
- //% property shim=String_::length
- length: number;
-
- [index: number]: string;
-}
-
-
-
-/**
- * Converts A string to an integer.
- * @param s A string to convert into a number.
- */
-//% shim=String_::toNumber
-declare function parseInt(s: string): number;
-
-interface Object {}
-interface Function {}
-interface IArguments {}
-interface RegExp {}
-
-
-declare interface Boolean {
- /**
- * Returns a string representation of an object.
- */
- //% shim=Boolean_::toString
- toString(): string;
-}
-
-declare namespace String {
-
- /**
- * Make a string from the given ASCII character code.
- */
- //% shim=String_::fromCharCode
- function fromCharCode(code: number): string;
-}
-
-
-declare interface Number {
- /**
- * Returns a string representation of a number.
- */
- //% shim=Number_::toString
- toString(): string;
-}
-
-/**
- * Numbers and arithmetic operators
- */
-declare namespace Math {
-
- /**
- * Returns the value of a base expression taken to a specified power.
- * @param x The base value of the expression.
- * @param y The exponent value of the expression.
- */
- //% shim=Math_::pow
- function pow(x: number, y: number): number;
-
- /**
- * Returns a pseudorandom number between 0 and `max`.
- */
- //% shim=Math_::random
- function random(max: number): number;
-
- /**
- * Returns the square root of a number.
- * @param x A numeric expression.
- */
- //% shim=Math_::sqrt
- function sqrt(x: number): number;
-}