*Question G7B06:
What is a shift register?*  

*Correct Answer is  A: A clocked array of circuits that passes data in steps along the array*  

### AI Response: (may contain errors)  

A shift register is a type of digital memory circuit used for storing and shifting data. 

### Explanation of the Correct Answer:
- **Correct Answer: A**  
  A shift register is indeed a clocked array of circuits that passes data in steps along the array. It consists of a series of flip-flops connected in a chain, where data can be shifted in or out with each clock pulse. This allows for serial data input and output, making it useful in various applications such as data storage, data transfer, and digital signal processing.

### Explanation of Incorrect Answers:
- **B: An array of operational amplifiers used for tri-state arithmetic operations**  
  This describes a different type of circuit. Operational amplifiers (op-amps) are used for analog signal processing, not for shifting digital data. Tri-state logic refers to a condition where a circuit can be in one of three states: high, low, or high impedance, which is not the function of a shift register.

- **C: A digital mixer**  
  A digital mixer is used to combine multiple digital signals into one, often in audio processing or telecommunications. This is not related to the function of a shift register, which is focused on data storage and shifting rather than mixing.

- **D: An analog mixer**  
  Similar to the digital mixer, an analog mixer combines multiple analog signals. This is also unrelated to the operation of a shift register, which deals with digital data.

### Summary:
- A shift register is specifically designed for shifting data in a digital format, making it essential for various digital applications. Understanding its function helps differentiate it from other types of circuits that serve different purposes.