: Digital systems can be asynchronous or asynchronous. Changing one or more inputs at any time in an asynchronous system may result in a change in the output state of the logic circuit. In synchronous systems, on the other hand, changes in the output state of the logic circuit are usually controlled by a clock signal. The clock signal can usually be a rectangular pulse or a square wave . This clock is connected to all parts of the signal system. Clock pulse transition will change the output state of the system. Transitions can be of two types . Namely: 1. Positive Going Transition ( Positive Going Transition ) Negative Going Transition Positive singing transition works when the clock pulse changes from 0 to 1. It is also called positive edge trigger. On the other hand in negative singing transitions the clock pulse works if it changes from 1 to 0. It is also known as negative edge trigger. Most digital systems are in principle synchronous, although they have some asynchronous components. Synchronous system design and troubleshooting is quite simple.