MECH 2301 Lecture Notes - Lecture 10: Word Processor
20 May 2018
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MECH 2301 Lecture 10 Notes
Introduction
Stream of Bytes
• IBM z/OS represents the opposite extreme, providing detailed record management
within its file management system.
• There are good arguments for either approach.
• It would certainly be reasonable to interpret the program and word processing files
mentioned above as a single stream of bytes, for example.
• Furthermore, we note that the structure of files can be complex, and everyone is
different.
• Treating all files in a similar way simplifies the file management programs, while at the
same time adding flexibility to the application programs and utilities
• Since each application program can define the contents of its files in any way convenient
to meet its own needs. Input and output redirection is simplified
• Since all data is treated in the same way, as a stream of bytes.
• The same is true for the use of program pipes, as described
• Conversely, treating all files as a stream of bytes requires significantly more effort on
the design of application and utility programs.
• ‘etrieal of data i the iddle of the strea, for exaple, is ore difficult he the
application program must keep track of its position in the file.
• A file management system that imposes well-designed standards on its files can simplify
data storage and retrieval and simplify application program design, without severely
limiting application flexibility.
• As a practical matter, much of the data that is useful to a user is logically represented in
record form.
• Data files whose records are always retrieved in sequence from the beginning of the file
are known as sequential files.
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