In this article you will get 8 Bit Common Bus Circuit With Tri State in Digital Works Software. It is little bit complex but very easy if you have its concept. Basic purpose of common bus is to reduce our complexity of buses when we transfer data from register to memory. We cannot afford to create separate but for each register so we make a common bus for all registers. Decoder will decide which register will send data on common bus. In this circuit there are 4 registers of 8 bit.