ABSTRACT
Computer programs communicate with the world by receiving inputs and delivering outputs through hardware such as your workstation keyboard and display, disk drives, tape drives, and network connections. FORTRAN programs do these input and output (I/O) operations by reading from and writing to logical I/O units. The actual transfers of data are performed by a set of subprograms that are part of FORTRAN, called the I/O library. When the FORTRAN compiler translates your source program into machine instructions, it inserts calls to library routines that execute any I/O statements you have used. The I/O library routines associate the logical I/O units mentioned in your source program with logical I/O devices such as file names and UNIX™ logical devices named in the directory /dev. These logical devices are in turn attached by UNIX™ to the appropriate physical I/O devices.
