An operating system (OS) is like a facilitator, providing an environment for application programs to run in. It provides an interface between computer hardware and the user of the application programs. Application programs are a stored set of instructions for responding to a specific request. Hardware are the physical devices that make up the system such as the monitor, keyboard, printer, ect. The OS typically includes anywhere from tens to thousands of built-in subroutines called …showed first 75 words of 1082 total…

…showed last 75 words of 1082 total…each individual I/O device. Most operating systems like Windows95 come with dozens of different drivers for each I/O device. DOS also uses drivers, but they are often so primitive that the applications perform device I/O by relying on low-level routines encoded in ROM (Read Only Memory - allows the data to be read but not written) in the computer’s BIOS (Basic Input/Output System) or by talking directly to the hardware.