How is the timing of instruction execution ensured in a computer system?

The timing of instruction execution in a computer system is primarily ensured by the Control Unit. The Control Unit is a critical component of the CPU that orchestrates the execution of instructions by directing the movement of data within the CPU and to other components of the computer. It generates control signals based on the instruction set architecture, effectively managing the sequence of operations that need to occur at precise times to ensure that instructions are executed correctly.

The Control Unit uses clock signals to synchronize the operations of the CPU, ensuring that each part of the instruction cycle (fetch, decode, execute) occurs in the right order and at the right moment. This precise timing is essential for the overall functionality of the computer system, as it allows multiple operations to happen seamlessly and in an orderly fashion, which is crucial for effective processing and performance.

In contrast, the other options do not manage timing in the same way. The data bus is responsible for transferring data between components but does not control the timing of operations. While the CPU plays a vital role in instruction execution, it relies on the Control Unit for coordination. External hardware interfaces typically facilitate communication with peripheral devices but do not regulate the timing of instruction execution within the CPU itself.