How does an operating system interface with hardware's firmware?

An operating system interfaces with hardware's firmware primarily through device drivers. Device drivers serve as the communication bridge between the operating system and hardware components. They convert the operating system's generic commands into specific tasks that the hardware can understand, thereby facilitating smooth interaction.

When the operating system needs to communicate with hardware, such as a printer, graphics card, or disk drive, it sends a request to the device driver associated with that specific hardware. The driver manages the data exchange by translating those requests into firmware commands that are compatible with the hardware, ensuring effective operation.

Kernels are indeed critical as they serve as the core part of the operating system that manages system resources and allows interaction with the drivers, but it is the device drivers that directly handle the specifics of interacting with the firmware. Meanwhile, the keyboard primarily serves as an input device rather than a mediator between firmware and the operating system. Applications, on the other hand, rely on system calls that interact with the operating system, but data exchange with hardware is not handled by them directly; rather, they depend on the underlying device drivers for that process.