Download Handout Storage functions and Output Functions What is a storage

Handout
Storage functions and Output Functions
What is a storage function?
This is the means by which information is saved permanently or temperately (until such time as
you wish to retrieve ordelete it). In a computer, storage is the place where data is held in an
electromagnetic or optical form for access by a computer processor. The memory is stored in
computer in in several different ways depending on how the information is used. There are two
broad storage media:

Primary storage – Random Access Memory (RAM) and Read Only Memory
(ROM)

Secondary Storage – which holds data on hard disks, tapes, and other devices
requiring input/output operations.
Primary storage alternatively referred to as internal memory, main memory, and primary
memory, a primary storage device is a medium that holds memory for short periods of time
while a computer is running. It’s much faster to access than secondary storage because of the
proximity of the storage to the processor or because of the nature of the storage devices. On the
other hand, secondary storage can hold much more data than primary storage.
Memory can be classified as volatile or non-volatile. An example of a volatile memory is
Random Access Memory (RAM); this means that information is stored only while there is an
electric current being applied to it (this storage is temporary). Non-volatile memory refers to
information that is permanently stored and cannot be lost if computer power is removed e.g.
Read Only Memory (ROM).
Secondary storage, sometimes called auxiliary storage or external storage, is non-volatile
storage that is not under the direct control of a computer's central processing unit (CPU) or does
not directly interact with an application.
Typically, secondary storage is used to back up primary storage through replication or
other data protection methods, which involves holding a secondary copy of the data. In a
business environment, an older network-attached storage (NAS) box, storage-area network
(SAN) or tape library may be used for secondary storage. Object storage devices can also be
used to implement secondary storage and lessen the demand on primary storage arrays. The
growth of corporate data has prompted many storage managers to move data to secondary
storage to ease the strain on primary storage systems to reclaim more expensive storage arrays
and maintain older data in an easily accessible form to satisfy business and regulatory
compliance requirements.
These secondary storage come in two form: Direct Access (DA) or Sequential Access (SA).
Sequential access means that a group of elements (such as data in a memory array or a disk file
or on magnetic tape data storage) is accessed in a predetermined, ordered sequence. Sequential
access is sometimes the only way of accessing the data, for example if it is on a magnetic tape or
tape reels.
Direct access is the ability to obtain data from a storage device by going directly to where it is
physically located on the device rather than by having to sequentially look for the data at one
physical location after another. A direct access storage device (DASD) has the electrical or
electromechanical means to be immediately positioned for reading and writing at any
addressable location on the device.
Examples of DA

Thumb drives

External Hard drives

Erasable Optical disks
What are output functions?
An output is when the computer communicates the results of the processed data. The data has
been transformed into useful information that we can see, hear and use. This processed data is
now information. As we have seen, computer output takes the form of screen or printer output.
Other forms of output include voice, microfilm, and various forms of graphics output.
These are place into various categories:
 Hard Copy – printed on paper or other permanent means.
 Soft Copy – displayed on screen or by other non-permanent means.
 Modem – allows computers to output information to telephone lines.
 Disk or tape – can have three uses: input, storage, and output.
Hard Copy
Hardcopy devices give the output in a tangible form like printed document on a paper. The
output is permanent. Printers, plotters are the examples of hardcopy O\P devices because they
print the output in hard paper.
A printer generate a hardcopy of output. E.g. of some printers are Dot Matrix, Inkjet printer,
Laser printer. Printers are the most popular hard copy output device. The purpose of the printer is
to put on paper the information displayed on the computer screen.
Plotters generates hard copies of drying such as lines, plants, machines, engineering maps,
building designs and graphics etc in a very accurate manner. Example graphs, charts, maps,
three-dimensional graphics. Vector plotters produce accurate drawings since they use absolute
coordinates to define an entity. Whereby Raster plotters produce images consisting of small dots.
Microfiche/Microfilm – the computer output produced are tiny images on rolls or sheets of
microfilm. Microfilm hold between 30 to 300 pages.
Softcopy
A soft copy is a document saved on a computer. It is the electronic version of a document, which
can be opened and edited using a software program. Softcopy output is information that is
intangible. The most common method of displaying a soft copy is through a computer monitor or
other display.
Soft Copy Output Devices included:
 Screen/Monitor/Video Display Unit (VDU)
 Audio-Output devices
 Video Output
 Sound Output Devices
 Voice Output Devices
Visual Display Units (VDU)
Monitors
This is the most common form of output devices. It resembles a television screen and is
commonly called a monitor. Like most early TVs, the early computer monitors were comprised
of a CRT (Cathode Ray Tube) and a fluorescent screen. Today, all monitors are created using flat
panel display technology.
Audio-Output devices includes those devices that output voice or voice-like sounds and those
that output music and other sounds.
Video Output- video Conferencing is a method whereby people in different geographical
locations can have a meeting seeing and hearing each other using computers and communication
software.
References
King, G., & Forbes, T. (2001). Information Technology Made Simple. Jamaica: Authors.
Leighton J. (2001). CXC lecture series information technology, revised Edition. Jamaica.
Rouse M, (n.d) Secondary storage definitions (para. 1 & 2). Retrieved from
http://searchstorage.techtarget.com/definition/secondary-auxiliary-storage
Rouse M, (n.d) Storage definition (para. 1). Retrieved from
http://searchstorage.techtarget.com/definition/storage
Primary Storage Device (n.d). Computer Hope (para. 1). Retrieved from
http://www.computerhope.com/jargon/p/primstor.htm