1.A device driver is a program that extends the operating system to support a device such as a disk or tape drive; or a program that enables an application to use a device such as a printer.Hardware devices such a sound cards, printers, scanner, and CD-ROM drive must each have the proper driver installed in order to run. 2.A line driver is a circuit that is used to increase the signal current in order to send data over long distances or to many circuit.