Private Sub Timer1_Tick(sender As System.Object, e As System.EventArgs) _
      Handles Timer1.Tick
        Static i As Single = 0
        i += 0.1
        If i > 3.14 Then i = -i
        Chart1.Series("Series1").Points.Add(Math.Sin(i))
        If Chart1.Series("Series1").Points.Count > 300 Then Chart1.Series( _
          "Series1").Points.RemoveAt(0)
    End Sub
    Private Sub Button1_Click_1(sender As System.Object, e As System.EventArgs) _
      Handles Button1.Click
        Timer1.Interval = 10
        Timer1.Enabled = Not Timer1.Enabled
    End Sub

--
while (!asleep()) sheep++;