(1) A pacemaker.  This is a device that is inserted in someone's chest to provide electrical impulses at regular intervals to help their heart beat.  If the device missed a beat, it may be fatal.(2) The Anti-lock Braking System (ABS) controller in a car.  When the driver of the car presses on the brake, this device controls the signals to the actual brake pads with the wheels.  If the device does not correctly manage the timing of the brake pads, the car will not stop correctly.Realtime OSs involve special programming that takes additional training for software engineers and is considered more difficult to get correct for safe applications.