diff --git a/sim/state/motor.ts b/sim/state/motor.ts
index ded9a837..e2a5c9f0 100644
--- a/sim/state/motor.ts
+++ b/sim/state/motor.ts
@@ -19,9 +19,15 @@ namespace pxsim {
                     console.log("motor before read");
                     for (let port = 0; port < DAL.NUM_OUTPUTS; ++port) {
                         const output = outputs[port];
+                        const speed = output ? Math.round(outputs[port].getSpeed()) : 0;
+                        const angle = output ? Math.round(outputs[port].getAngle()) : 0;
+                        const tsi = MotorDataOff.TachoSensor + port * MotorDataOff.Size;
                         data[MotorDataOff.TachoCounts + port * MotorDataOff.Size] = 0; // Tacho count
-                        data[MotorDataOff.Speed + port * MotorDataOff.Size] = output ? outputs[port].getSpeed() : 0; // Speed
-                        data[MotorDataOff.TachoSensor + port * MotorDataOff.Size] = output ? outputs[port].getAngle() : 0; // Count
+                        data[MotorDataOff.Speed + port * MotorDataOff.Size] = speed; // Speed
+                        data[tsi] = angle & 0xff; // Count
+                        data[tsi + 1] = (angle >> 8) & 0xff; // Count
+                        data[tsi + 2] = (angle >> 16) & 0xff; // Count
+                        data[tsi + 3] = (angle >> 24) & 0xff; // Count
                     }
                 },
                 read: buf => {
diff --git a/sim/state/output.ts b/sim/state/output.ts
index e85ca5a4..a3b93f8e 100644
--- a/sim/state/output.ts
+++ b/sim/state/output.ts
@@ -37,7 +37,7 @@ namespace pxsim {
                         case DAL.opOutputStepSpeed: {
                             // step speed
                             const port = buf.data[1];
-                            const speed = buf.data[2];
+                            const speed = buf.data[2] << 24 >> 24; // signed byte
                             // note that b[3] is padding
                             const step1 = buf.data[4];
                             const step2 = buf.data[5]; // angle
@@ -59,7 +59,7 @@ namespace pxsim {
                         case DAL.opOutputSpeed: {
                             // setSpeed
                             const port = buf.data[1];
-                            const speed = buf.data[2];
+                            const speed = buf.data[2] << 24 >> 24; // signed byte
                             const motors = ev3board().getMotor(port);
                             motors.forEach(motor => motor.setSpeed(speed));
                             return 2;
diff --git a/sim/visuals/board.ts b/sim/visuals/board.ts
index 152bf5ef..a5a1d040 100644
--- a/sim/visuals/board.ts
+++ b/sim/visuals/board.ts
@@ -374,7 +374,7 @@ namespace pxsim.visuals {
                 now = Date.now();
                 delta = now - then;
                 if (delta > interval) {
-                    then = now - (delta % interval);
+                    then = now;
                     that.updateStateStep(delta);
                 }
             }