Here, that layer doesn't exist. This program takes the place of the OS, and communicates with the hardware directly, without an OS in the way. This can be done

Here, that layer doesn't exist. This program takes the place of the OS, and communicates with the hardware directly, without an OS in the way. This can be done because ages ago, the PC hardware interface was almost completely standardised, and all PCs to this day implement that standard for backwards compatibility.