An operating system also provides facilities to hide the details of the hardware.
It constructs higher level resources out of lower level ones.
For instance,
the hardware provides terminal interrupts for input from and output to a terminal.
An operating system
provides higher level facilities to read and write characters, which relieve
a user program from the task of handling interrupts
from the terminal.
Similarly,
the hardware provides an unstructured disk.
The operating system provides a higher level structure consisting of files.