Minecraft wiki entry for Zero-ticking, associated text: One method of doing so is using tile tick priorities. Since comparators are processed in a tick later than repeaters, one can generate a 0-tick pulse by powering a redstone line using this behavior. In this example, redstone repeater is used to power the output line, and a comparator is used to power a piston which will remove the block in front of repeater to depower the line. Since the comparator always powers after repeaters, the redstone line will always turn off after it turns on, creating a reliable 0-tick pulse. The advantage to this 0-tick generator is that it's 0-tick pulse is earlier in a tick relative to 0-tick pulses generated through other methods.