*Question E6C03:
What is tri-state logic?*  

*Correct Answer is  A: Logic devices with 0, 1, and high-impedance output states*  

### AI Response: (may contain errors)  

Tri-state logic is a type of digital logic circuit that can exist in three different states: 0, 1, and high-impedance (often referred to as "Z" or "Hi-Z"). Here's why the correct answer is correct and why the other choices are incorrect:

1. **Correct Answer: A - Logic devices with 0, 1, and high-impedance output states**

   - **Explanation**: Tri-state logic allows a digital circuit to have an additional state beyond the typical binary states (0 and 1). The high-impedance state effectively disconnects the output from the circuit, allowing multiple outputs to be connected to a single line without interference. This is useful in bus systems where multiple devices need to share the same communication line.

2. **Incorrect Choices**:

   - **B: Logic devices that utilize ternary math**
     - **Explanation**: Ternary math involves three distinct values (e.g., -1, 0, 1) for computation, which is different from tri-state logic. Tri-state logic is not about performing calculations with three values but about controlling the output state of a logic device.

   - **C: Logic with three output impedances which can be selected to better match the load impedance**
     - **Explanation**: This choice describes a system that adjusts impedance to match a load, which is unrelated to the concept of tri-state logic. Tri-state logic is about controlling the output state, not impedance matching.

   - **D: A counter with eight states**
     - **Explanation**: A counter with eight states refers to a device that can count from 0 to 7, which is unrelated to tri-state logic. Tri-state logic is about the output state of a logic device, not counting states.

In summary, tri-state logic is essential for enabling multiple devices to share a single communication line without interference, by allowing outputs to be in a high-impedance state when not in use.