diff --git a/libs/core/_locales/core-jsdoc-strings.json b/libs/core/_locales/core-jsdoc-strings.json
index 220a5e37..c1adf164 100644
--- a/libs/core/_locales/core-jsdoc-strings.json
+++ b/libs/core/_locales/core-jsdoc-strings.json
@@ -45,6 +45,7 @@
   "Math.pow|param|y": "The exponent value of the expression.",
   "Math.random": "Return a pseudorandom number between 0 and `limit`.",
   "Math.randomBoolean": "Generates a `true` or `false` value randomly, just like flipping a coin.",
+  "Math.random|param|limit": "the upper bound of the number generated, eg: 4.",
   "Math.sign": "Returns the sign of the x, indicating whether x is positive, negative or zero.",
   "Math.sign|param|x": "The numeric expression to test",
   "Math.sqrt": "Return the square root of a number.",
diff --git a/sim/visuals/microbit.ts b/sim/visuals/microbit.ts
index 8dd66fe0..3cd4c9b5 100644
--- a/sim/visuals/microbit.ts
+++ b/sim/visuals/microbit.ts
@@ -477,10 +477,10 @@ namespace pxsim.visuals {
                 accessibility.makeFocusable(this.pins[index]);
                 accessibility.setAria(this.pins[index], "slider", this.pins[index].firstChild.textContent);
                 this.pins[index].setAttribute("aria-valuemin", "0");
-                this.pins[index].setAttribute("aria-valuemax", "1023");
+                this.pins[index].setAttribute("aria-valuemax", pin.mode & PinFlags.Analog ? "1023" : "100");
                 this.pins[index].setAttribute("aria-orientation", "vertical");
-                this.pins[index].setAttribute("aria-valuenow", text.textContent);
-                accessibility.setLiveContent(text.textContent);
+                this.pins[index].setAttribute("aria-valuenow", text ? text.textContent : v);
+                accessibility.setLiveContent(text ? text.textContent : v);
             }
         }