diff --git a/sim/dalboard.ts b/sim/dalboard.ts
index 295e6f48..f95ff7a8 100644
--- a/sim/dalboard.ts
+++ b/sim/dalboard.ts
@@ -10,8 +10,10 @@ namespace pxsim {
         // updates
         updateSubscribers: (() => void)[];
 
-        // builtin state
+        // builtin
         builtinParts: Map<any>;
+        builtinVisuals: Map<() => visuals.IBoardPart<any>>;        
+        builtinPartVisuals: Map<(xy: visuals.Coord) => visuals.SVGElAndSize>;
 
         constructor() {
             super()
@@ -25,6 +27,8 @@ namespace pxsim {
             }
 
             this.builtinParts = {};
+            this.builtinVisuals = {};
+            this.builtinPartVisuals = {};
         }
 
         kill() {
@@ -67,6 +71,14 @@ namespace pxsim {
             this.builtinParts["lightsensor"] = this.lightSensorState = new LightSensorState();
             this.builtinParts["compass"] = this.compassState = new CompassState();
             this.builtinParts["neopixel"] = this.neopixelState = new NeoPixelState();
+
+            this.builtinVisuals["buttonpair"] = () => new visuals.ButtonPairView();
+            this.builtinVisuals["ledmatrix"] = () => new visuals.LedMatrixView();
+            this.builtinVisuals["neopixel"] = () => new visuals.NeoPixelView();            
+
+            this.builtinPartVisuals["buttonpair"] = (xy: visuals.Coord) => visuals.mkBtnSvg(xy);
+            this.builtinPartVisuals["ledmatrix"] = (xy: visuals.Coord) => visuals.mkLedMatrixSvg(xy, 8, 8);
+            this.builtinPartVisuals["neopixel"] = (xy: visuals.Coord) => visuals.mkNeoPixelPart(xy);            
         }
 
         receiveMessage(msg: SimulatorMessage) {
diff --git a/sim/definitions.ts b/sim/definitions.ts
index 8e553c4b..b48976e3 100644
--- a/sim/definitions.ts
+++ b/sim/definitions.ts
@@ -53,16 +53,6 @@ namespace pxsim {
         marginWhenBreadboarding: [0, 0, 80, 0],
     }
 
-    export const builtinComponentSimVisual: Map<() => visuals.IBoardPart<any>> = {
-        "buttonpair": () => new visuals.ButtonPairView(),
-        "ledmatrix": () => new visuals.LedMatrixView(),
-        "neopixel": () => new visuals.NeoPixelView(),
-    };
-    export const builtinComponentPartVisual: Map<(xy: visuals.Coord) => visuals.SVGElAndSize> = {
-        "buttonpair": (xy: visuals.Coord) => visuals.mkBtnSvg(xy),
-        "ledmatrix": (xy: visuals.Coord) => visuals.mkLedMatrixSvg(xy, 8, 8),
-        "neopixel": (xy: visuals.Coord) => visuals.mkNeoPixelPart(xy),
-    };
 
     //TODO: add multiple board support
     export const CURRENT_BOARD = MICROBIT_DEF;
diff --git a/sim/instructions.ts b/sim/instructions.ts
index 055215c7..acf6e25e 100644
--- a/sim/instructions.ts
+++ b/sim/instructions.ts
@@ -282,13 +282,14 @@ namespace pxsim.instructions {
         return div;
     }
     function mkCmpDiv(cmp: "wire" | PartVisualDefinition, opts: mkCmpDivOpts): HTMLElement {
+        let state = runtime.board as pxsim.CoreBoard;
         let el: visuals.SVGElAndSize;
         if (cmp == "wire") {
             el = visuals.mkWirePart([0, 0], opts.wireClr || "red", opts.crocClips);
         } else {
             let partVis = <PartVisualDefinition>cmp;
             if (typeof partVis.builtIn == "string") {
-                let cnstr = builtinComponentPartVisual[partVis.builtIn];
+                let cnstr = state.builtinPartVisuals[partVis.builtIn];
                 el = cnstr([0, 0]);
             } else {
                 el = visuals.mkGenericPartSVG(partVis);
diff --git a/sim/visuals/boardhost.ts b/sim/visuals/boardhost.ts
index 172670a3..6f64d44d 100644
--- a/sim/visuals/boardhost.ts
+++ b/sim/visuals/boardhost.ts
@@ -159,7 +159,7 @@ namespace pxsim.visuals {
             if (partInst.simulationBehavior) {
                 //TODO: seperate simulation behavior from builtin visual
                 let builtinBehavior = partInst.simulationBehavior;
-                let cnstr = builtinComponentSimVisual[builtinBehavior];
+                let cnstr = this.state.builtinVisuals[builtinBehavior];
                 let stateFn = this.state.builtinParts[builtinBehavior];
                 part = cnstr();
                 part.init(this.state.bus, stateFn, this.view, partInst.params);