Question
What is tri-state logic?
Answer Options
- A) Logic devices with 0, 1, and high-impedance output states
- B) Logic devices that utilize ternary math
- C) Logic with three output impedances which can be selected to better match the load impedance
- D) A counter with eight states
Correct Answer: A
Explanation
Standard digital logic circuits have only two defined output states: high (logic 1) and low (logic 0). However, in digital bus systems (where multiple devices share the same data lines), a mechanism is needed to allow a device to essentially disconnect itself when it is not actively transmitting data.
Tri-state logic (or three-state logic) provides this third option. These logic devices feature a control pin that allows the output to assume 0, 1, and a high-impedance (Hi-Z or floating) output state. The high-impedance state effectively disconnects the output from the bus, allowing another device to control the bus line without causing a signal conflict or short circuit.
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