*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 refers to a type of digital logic that can exist in three different states: 

- Logic 0
- Logic 1
- High-impedance (often represented as "Z")

This high-impedance state allows multiple devices to connect to a single output line without interfering with each other, making it essential in bus systems where multiple devices may need to share the same communication line.

### Explanation of the Correct Answer:
- **Correct Answer (A)**: Logic devices with 0, 1, and high-impedance output states.
  - This is correct because tri-state logic specifically allows for three distinct states, enabling devices to effectively "disconnect" from the circuit when not in use, preventing signal interference.

### Explanation of Incorrect Answers:
- **Choice B**: Logic devices that utilize ternary math.
  - This is incorrect because ternary logic involves three distinct values (often 0, 1, and 2), whereas tri-state logic specifically refers to the three states of output (0, 1, and high-impedance) and does not involve a third numeric value.

- **Choice C**: Logic with three output impedances which can be selected to better match the load impedance.
  - This is incorrect because tri-state logic does not refer to varying output impedances; it specifically refers to the output states of the logic devices, not their impedance characteristics.

- **Choice D**: A counter with eight states.
  - This is incorrect because a counter with eight states would typically be a binary counter that counts from 0 to 7 (which requires 3 bits), but it does not relate to tri-state logic.

### Summary:
Tri-state logic is crucial in digital circuits, especially in applications where multiple devices need to share a single data line without causing conflicts. Understanding this concept is vital for designing and troubleshooting digital systems.