Device Drivers in UNIX, MS-DOS and Windows System
Though device drivers are in effect add-on modules they are however considered to be part of system because they are closely integrated with I/O Control System that deals with I/O related system calls.
In UNIX device drivers are typically linked onto object code of kernel (core of operating system). This means that when a new device is to be used that was not included in original construction of operating system, UNIX kernel has to be re-linked with new device driver object code. This scheme has advantages of run-time efficiency and simplicity however the shortcoming is the addition of a new device needs regeneration of the kernel. In UNIX every entry in /dev directory is associated with a device driver that manages communication with the related device. A list of few device names is as displayed below:
Device name Description
/dev/console system console
/dev/tty01 user terminal 1
/dev/tty02 user terminal 2
/dev/lp line printer
/dev/dsk/f03h 1.44 MB floppy drive