Accessing Files Programmer's Guide (32650-90885)

14 Chapter1
Introduction
processed, and output as a single unit. Logically related records are grouped into sets
known to the file system as files, which may be kept in any storage medium or sent to any
input/output peripheral (as illustrated in Figure 1-2. below).
Figure 1-2. Records/Files Relationship
Since all input/output operations are done through the mechanism of files, you may access
very different devices in a standard, consistent way. It does not make much difference to
you whether you read your file from a disk or from a magnetic tape, because the file system
permits you to treat all files in the same way. This property of the file system gives your
program device independence; the name and characteristics assigned to a file when it is
defined in a program do not restrict that file to residing on the same device every time the
program is run. You, the user, need only reference the file by the file name assigned to it
when it was created, and the file system determines the device or disk address where the
file is stored and access the file for you. (Of course, you should be aware of the properties of
the device you're using. For example, the MPE/iX file system permits you to read a file
from a line printer.)