The 1M resistor does part of the trick. The signal doesn't stay at high with the 1M resistor connected, but it shows the same signal sequence as without any resistor, so the signal peaks are still much shorter than stated in the spec 
The 1M resistor does part of the trick. The signal doesn't stay at high with the 1M resistor connected, but it shows the same signal sequence as without any resistor, so the signal peaks are still much shorter than stated in the spec