MECH 2301 Lecture Notes - Lecture 12: Filename Extension
20 May 2018
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MECH 2301 Lecture 12 Notes
Introduction
Windows Extension
• A file may be considered to be either binary or alphanumeric
• Although, of course, even alphanumeric characters are actually stored in binary form
• The file may be characterized by the way data is to be retrieved.
• A file might be temporary or permanent.
• A file might be writeable or write-protected. There are other possibilities.
• Files may also have such attributes as the date of origination, the most recent update,
and information about who has the right to access, update, and delete the file.
• Some systems allow a data file to specify the program it is to be used with.
• This property is called an association. In such a case, calling the data file automatically
loads and starts the associated program file.
• For example, Windows uses the file extension to create the necessary association.
• Other operating systems may store the association as a property of the data file.
• The previous discussion has focused on the logical view of a file, the meaning of its
contents
• Its attributes as viewed by the user, operating system utilities, and application
programs.
• All the files, plus all the attributes and information describing those files, are stored,
controlled, and manipulated by the file management system.
• The physical view of a file is the way in which the file is actually stored within the
computer system.
• We have already indicated that the physical view of a file may look very different from
the file’s logical view.
• Physically, the file on nearly every system is stored and manipulated as a group of
blocks.
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