STORAGE DEVICES

These are devices that hold data or information on a file when it is needed for processing.  Processed data may also be put onto external storage devices.  Most computers have a backing storage.  Backing storage is necessary because memory is volatile and usually limited.

ADVANTAGES OF MEMORY

➢    Memory is fast because it is accessed electronically and no mechanical components are involved.

Advantages of backing storage

➢    Backing storage is non-volatile and contents stored is relatively more permanent when compared with memory.

➢    Backing storage provides cheap and almost unlimited amount of storage.

Disadvantages of Memory

➢    Most memory (except ROM, flash memory, and CMOS) is volatile and contents must be transferred to backing storage before the computer is turned off.

➢    Memory is expensive and its storage size on a computer system is usually limited when compared with backing storage.

Disadvantages of backing storage

➢    Backing storage is slow because of the mechanical components involved.

N.B

(a)      A Storage Medium. This is a physical material on which a computer keeps data, instructions and information for future use.

(b)      Storage capacity. This is the number of bytes (i.e characters) a storage medium can hold.  Common types of storage media are:

-       Floppy disk

-       Hard disk

-       Compact disk

-       Tape

-       Zip drive

-        

Others include:

-       Mo card

-       PC card

-       Smart card

-       Micro film and microfiche

-       Online storage

          A storage device records and retrieves items to and from a storage medium.

(c)      Storage devices act as input devices when they read and act as output devices when they write.

(d)      Reading. This is the process of transferring data, instructions and information from a storage medium into memory.

(e)      Writing. This is the process of transferring items from memory to storage medium.

(f)       The speed of a storage device is defined by its access time, which the amount of time it takes to locate an item on a medium.