FILE SYSTEMS
The file system is one of the most visible facilities of an operating system. Since the early days of operating
systems, the OS has provided a permanent means to store information. A file collects related information
together and provides access to the information via the name of the file. Over time, many file types have been
developed to suit different purposes.
Just as files organize information, file directories organize files. Today it seems almost beyond question that
file directories should be of ???tree??? form, but that wasn??™t always true.
File Types
A widely used file type is the fixed-length record file. The file consists of records, or rows, each of which
contains values for each of the fields of a record. This form was natural, especially in the days of punched cards.
When one visualized a record, one saw in one??™s mind??™s eye a punched card. The card??™s 80 columns were divided
into sets of columns (fields), where the values of the fields were punched. Such a conception of information
storage seems natural for many purposes. Imagine your holiday greeting card list as a fixed-length record file,
where each record represents a person, and each person record has a field for name, for street address, for city, etc.
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