Which statement is not a function of the CPU?

• A. Execute the operating system
• B. Manage memory
• C. Monitor inputs and energize outputs
• D. Perform analog-to-digital conversion

Answer: (D)

The central idea here is what the CPU is responsible for versus what specialized hardware handles. The CPU runs instructions, including the operating system, and it coordinates memory management and input/output operations by processing data and directing other hardware. In a PLC or similar system, the CPU executes the control program, manages addresses and data, and communicates with input and output modules to monitor sensors and energize actuators.

Analog-to-digital conversion, on the other hand, is done by dedicated analog hardware. The ADC takes an analog signal, converts it to a digital value, and then the CPU can read that value and use it in its logic. The CPU does not perform the conversion itself; it orchestrates and uses the results from the ADC hardware. Therefore, the statement about performing analog-to-digital conversion is not a function of the CPU.