What kinds of things get stored in read-only memory, as opposed to storing them on the hard drive?
When you first turn on a typical computer, it must run an initial program that sets up the operating system. This initial program has to run even before the computer is able to interact with its hard drive, so the program must be available at the very instant the computer’s power becomes available. Read-only memory is used for this initial bootup operation. Unlike normal random access memory, which is usually “volatile” and loses its stored information when power is removed, read-only memory retains its information without power. When you turn on the computer, this read-only memory provides the instructions the computer uses to begin loading the operating system from the hard drive.