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Unformatted text preview: rage. Moreover, to protect the
data against natural calamities, it is suggest to store the backup media.with the backed up
data in a building that is away from the building where the computer system whose data
is backed up is located.
We saw that hard disks are used as on-line secondary storage devices in most computer
systems of today. However, the data access speed of a hard disk is much slower than that
of a semiconductor RAM (recall that RAM chips are used for main memory). This is
because hard disks involve mechanical movements, whereas semiconductor RAMs are
pure electronic devices. To make applications execute faster, in some computer systems a
block of semiconductor RAM chips (other than the RAM chips used for the main
memory) is used as a simulated disk. That is, an application to be executed is first loaded
from the hard disk into the simulated disk and then only its execution is started. The
application executes faster than normal in this case because the method avoids most of
the delay that might be caused by frequent calls to the hard disk for data loading during
The RAM chips used as a simulated disk are often referred to as a RAM disk, or a silicon
disk, or a pseudo disk. These RAM chips may be placed on an add-on circuit board that
fits inside the main computer box, or they may be housed in a separate cabinet. In either
case, these extra RAM chips look just like a disk drive to the control programs used in the
computer's operating system. Note that RAM disk is not really a disk at all.
A RAM disk greatly helps in enhancing the speed of the computer system because the
CPU can now access the desired data almost instantly from the RAM disk instead of waiting for few milliseconds to obtain the same data from the hard disk. However, RAM
chips are volatile and the data stored in them are lost when power is switched off. Thus,
programs and data files produced during a processing session must be stored on a
permanent storage device, such as a hard disk...
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This document was uploaded on 04/07/2014.
- Spring '14