What application instruction that make the computer hardware work?

The CPU does all the actual work and there can easily be a hundred or more separate instructions that a modern CPU understands, each of which does a very minute job, whether it is to move a value into a register or into memory, or to compare register values, or to perform simple arithmetic upon them, and so on. Common interfaces provided by the BiOS allow the CPU to interact with the basic hardware components in order to load an operating system, while the operating system itself provides more specific device control via driver software.