Chap4_Sec_Storage_complete

Chap4_Sec_Storage_complete - Secondary Storage Chap_2 =>...

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1 Secondary Storage Chap_2 => Main Memory => Stores information (to be used by the CPU) temporarily . A need for a permanent storage => Secondary Storage Mainly: Hard Disk Floppy Disk External Storage (Tapes, Cartridges, …)
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2 Why organize Data? To easily fetch a piece of data (e.g a File), you should know its location in advance. Analogy: To fetch an item from a book, you consult the Index, you look for the Item, then you go to the specified page. Ε So, data need to be organized Ε The same applies for electronic data
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3 How Are Data Stored? The manner with which data is stored regulates the Access method 2 Main Access Methods: Sequential-Access Direct-Access
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4 Sequential-Access Data are stored in a sequential order Data are accessed sequentially Ε Access to any piece of data requires starting from the beginning. Analogy: To access a song in the middle of a cassette tape, you have to start (assuming you are at the beginning of the tape) from the first song.
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5 Direct-Access Also called Random Access Any piece of data can be accessed without
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This note was uploaded on 11/04/2009 for the course SSE CSC 1400 taught by Professor Mhamdi during the Spring '09 term at Al Akhawayn University.

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Chap4_Sec_Storage_complete - Secondary Storage Chap_2 =>...

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