diff --git a/libs/base/sim/control.ts b/libs/base/sim/control.ts
index 423427bdb..849c3ac65 100644
--- a/libs/base/sim/control.ts
+++ b/libs/base/sim/control.ts
@@ -43,6 +43,12 @@ namespace pxsim.control {
         })
         const cb = getResume();
     }
+    export function singleSimulator() {
+        pxsim.Runtime.postMessage(<pxsim.SimulatorCommandMessage>{
+            type: "simulator",
+            command: "single"
+        })
+    }
     export function waitMicros(micros: number) {
         thread.pause(micros / 1000); // it prempts not much we can do here.
     }