In many communication and networking systems, the signal transmitted on the communication line uses a non- return- to- zero (NRZ) format. USB uses a specific version referred to as non- return- to- zero inverted (NRZI). A circuit that converts any message sequence of 0s and 1s to a sequence in the NRZI format is to be designed. The mapping for such a circuit is as follows:(a) If the message bit (the input) is a 0, then the NRZI format message (the output) contains an immediatechange from 1 to 0 or from 0 to 1, depending on the current NRZI value.(b) If the message bit is a 1, then the NRZI format message remains fixed at 0 or 1, depending on the currentNRZI value.