With tri-state logic, a logic gate can be effectively disconnected from the circuit rather than assuming the normal 0 and 1 logic levels. This video goes into more detail on what it means to output a 0 or 1 and then describes how and why we'd want to output neither. This detail is essential to how a bus works. Support me on Patreon: https://www.patreon.com/beneater See https://eater.net/bbcpu8-registers for more.