Page 215 - DCAP103_Principle of operating system

Principles of Operating Systems

Notes Self Assessment
Multiple choice questions:
1. Which of the following systems software does the job of merging the records from two
files into one?
( a) Security software (b) Utility program
( c) Networking software (d) Documentation system
( e) None of the above
2. Which directory implementation is used in most Operating System?
( a) Single level directory structure (b) Two level directory structure
( c) Tree directory structure (d) Acyclic directory structure
Fill in the blanks:
3. A database system is more efficient to implement the ....................... in the operating system.
4. To select two or more separate file, hold down the ....................... key and click on each
filename.
5. We can rename a file or folder by choosing ....................... option.

6.3 File Access

• Sequential: Process files from beginning to end, in order, one record after the other. For
example, if we want to read a document from beginning to end, we typically start at the
beginning and read page, by page until we reach the end.

• Direct: Process file by accessing the content in no specific order. For example, if we only want
to read page 1013 it makes sense to reposition (seek) to page 1013 and read the page.

6.4 Access Methods

An access method defines the way processes read and write files. We study some of these below.
6.4.1 Sequential Access

Under this access method, the entire file is read or written from the beginning to the end
sequentially. Files in popular programming languages such as Pascal and Ada provide such
access. The file is associated with a read/write mark, which is advanced on each access. If several

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