diff --git a/pxtarget.json b/pxtarget.json
index a71fec58..9e16d6ed 100644
--- a/pxtarget.json
+++ b/pxtarget.json
@@ -75,7 +75,13 @@
     },
     "simulator": {
         "autoRun": true,
-        "aspectRatio": 0.69
+        "aspectRatio": 1.22,
+        "partsAspectRatio": 0.69,
+        "builtinParts": {
+            "accelerometer": true,
+            "buttonpair": true,
+            "ledmatrix": true
+        }
     },
     "compileService": {
         "yottaTarget": "bbc-microbit-classic-gcc",
@@ -136,4 +142,4 @@
         "userVoiceApiKey": "WEkkIGaj1WtJnSUF59iwaA",
         "userVoiceForumId": 402381
     }
-}
+}
\ No newline at end of file
diff --git a/sim/visuals/boardhost.ts b/sim/visuals/boardhost.ts
index 8cb9c0c8..1a4c4b8a 100644
--- a/sim/visuals/boardhost.ts
+++ b/sim/visuals/boardhost.ts
@@ -14,16 +14,16 @@ namespace pxsim.visuals {
         constructor(state: DalBoard, boardDef: BoardDefinition, cmpsList: string[], cmpDefs: Map<ComponentDefinition>, fnArgs: any) {
             this.state = state;
             let onboardCmps = boardDef.onboardComponents || [];
-            let activeComponents = cmpsList.filter(c => onboardCmps.indexOf(c) < 0);
+            let activeComponents = (cmpsList || []).filter(c => onboardCmps.indexOf(c) < 0);
             activeComponents.sort();
 
-            if (boardDef.visual === "microbit") {
+          //  if (boardDef.visual === "microbit") {
                 this.boardView = new visuals.MicrobitBoardSvg({
                     runtime: runtime,
                     theme: visuals.randomTheme(),
                     disableTilt: false
                 });
-            } else {
+         //   } else {
                 //TODO: port Arduino/generic board
                 // this.boardView = new visuals.GenericBoardSvg({
                 //     boardDef: boardDef,
@@ -32,7 +32,7 @@ namespace pxsim.visuals {
                 //     runtime: runtime,
                 //     fnArgs: fnArgs
                 // })
-            }
+        //    }
 
             const VIEW_WIDTH = "100%";
             const VIEW_HEIGHT = "100%";