Solution

The correct answer is Option 1

Key Points

• The sequence of operations for a CPU program to input data follows a logical order to ensure proper data flow and processing.
• The correct sequence is as follows:
  1. A. Read status register: The CPU first reads the status register to determine the current state of the device or peripheral.
  2. B. Check flag bit: The CPU then checks the flag bit to identify if the device is ready to send data.
  3. C. Read Data Register: If the device is ready, the CPU reads the data from the data register.
  4. D. Transfer data to memory: Finally, the CPU transfers the data from the data register to memory for further use.

Additional Information

• Read status register: The status register provides critical information about the state of the device, such as whether it is busy or ready.
• Check flag bit: The flag bit indicates the readiness of the device. For example, it may show whether the input buffer is full or empty.
• Read Data Register: Once the flag indicates readiness, the CPU accesses the data register to retrieve the input data.
• Transfer data to memory: The data is finally written to memory for later processing by the program.

Hence, the correct answer is: Option 1) A, B, C, D