Microsoft Office Tutorials and References
In Depth Information
Storage Media
Complementary metal oxide semiconductor CMOS , pronounced “SEE-moss”) (
memory is a chip installed on the motherboard that is activated during the boot process
and identifi es where essential software is stored. A small rechargeable battery powers
CMOS so its contents are saved when the computer is turned off. Unlike ROM, which
cannot be changed, CMOS changes every time you add or remove hardware; therefore,
CMOS is often referred to as semipermanent memory . CMOS stores the date and time
because it retains its contents when the computer is turned off.
Storage Media
On a computer, all data and instructions are stored as fi les. A computer fi le is a named
collection of stored data. An executable fi le contains the instructions that tell a computer
how to perform a specifi c task; for instance, the fi les used when the computer starts are
executable. A data fi le is created by a user; for instance, a report you write with a word
processing program can be saved as a data fi le.
Files you want to use later must be saved to a location where the computer can access
them when you want them. Because RAM retains data only while the power is on, your
computer must have a more permanent storage option. As Figure 9 shows, a storage
device receives data from RAM and stores it on a storage medium, such as a hard disk
drive, CD, or DVD. Later the data can be read and sent back to RAM to use again. The
information stored in RAM can be retrieved more quickly than information that is stored
permanently.
Figure 9
Storage and RAM
A storage device
receives information
from RAM, writes it on
the storage medium,
and reads and then
sends it back to RAM.
A storage device
receives information
from RAM, writes it on
the storage medium,
and then reads and
sends it back to RAM
DVD drive
storage medium
storage device
storage device
retrieve (read)
store (write)
RAM
 
 
 
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