Files serve as the connecting link between a program and the device used for I/O. Each file on the system has an associated file description which describes the file characteristics and how the data associated with the file is organized into records and fields.
In order for a program to perform any I/O operations, it must identify the file description(s) the program is referencing, what type of I/O device is being used, and how the data is organized. This chapter provides general information on:
Information on how to use externally and program-described files with different device types is found in subsequent chapters.