If you really want to know how a car works, you need to open the hood and take a look at the parts that make it go. The same is true for your computer. Open the case of your computer and you’ll see the actual parts that make your computer go: hard disk drives and disk controllers, central processing units, memory modules, and more, all connected via wires or circuitry to your computer’s motherboard.
But attaching a myriad of devices with wires and circuitry to a motherboard isn’t what makes them work together. What makes them work together is your computer’s firmware interface, which acts as the intermediary among devices; their internal code, if present; and higher-level processes.