A logic family that may be in one of three states rather than the usual two-high,low,or high impedance.In the high impedance state,output voltage is unaltered. Logic in a high impedance state may be easily and permanently connected to a bus.

• 一种可以是三个状态之一而不是两个状态之一的逻辑电路体系。三个状态是高、低或高阻抗。在高阻抗状态，输出电压不改变。高阻抗状态的逻辑电路可以容易并永久地连接到某总线。