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Alternatively referred to as storage, storage media, or storage medium, a storage device is a hardware device capable of holding information. There are two storage devices used in computers; a primary storage device such as computer RAM and a secondary storage device such as a computer hard drive.For the primary storages their example are
a) RAM
RAM is an acronym for Random-Access Memory which means the data and program in RAM can be read and written.
Function of RAM
1. RAM is the main memory in a computer. The data in RAM can be read (retrieved) or written (stored)
2. It stores data and programs that can be accessed directly by the processor.
3. RAM stores data during and after processing.
b) ROM
ROM is an acronym for Read-Only Memory which means the data or program in ROM can just be read but cannot be written at all.
Function of ROM :
1. ROM is another type of memory permanently stored inside the computer. ROM is non-volatile. Its holds the programs and data when the computer is powered off.
2. Many complex functions, such as start up operating instructions, translators for high-level languages and operating systems are placed in ROM memory.
3. All the contents in ROM can be accessed and read but cannot be changed.
The secondary storage could be a removable, internal, or external storage. In the picture to the right, is an example of a Drobo, an external secondary storage device.
Types of computer
storage for secondary storages :
- Floppy Diskette
- CD-ROM disc
- CD-R and CD-RW disc
- Jump drive and USB flash drive
- Zip diskette
- Hard disk drive
Tip: Keep in
mind that although these drives do send and receive information, they
are not considered an input
or output
device.
Floppy
Disk Drive
CD-ROM
Interface
- IDE/ATA - One of the most commonly used interfaces for disc drives.
- Panasonic - Older proprietary interface.
- Parallel - Interface used with old external CD-ROM drives.
- PCMCIA (PC Card) - Interface sometimes used to connect external disc drives to laptop computers.
- SATA - Replacing IDE as the new standard to connect disc drives.
- SCSI - Another common interface used with disk and disc drives.
- USB - Interface most commonly used to connect external disc drives.
CD-R
Alternatively referred to asa cd
writer, CD-WO (Write once),
WORM (Write Once Read Many) drive. CD-R is short for CD-Recordable and
is a
writable disc and drive that is capable of having information written to
the
disc once and then having that disc read many times after that. If the
data is
not written to the disc properly, has errors, or has the incorrect
information
that disc or portions of that disc cannot be erased and is often
jokingly
referred to as a coaster.
A CD-R
disc is coated with a photosensitive organic dye that
allows a user to record information. Once the CD-R disc is placed within
the
computer, the recording process begins. The laser inside the drive heats
the
dye to reveal areas that diffuse the light like a traditional CD pit.
The CD-R
drive does not create pits on the CD; instead the burner creates
reflective
sections on the CD causing the computer's CD-ROM laser to interpret it
as a
pit. Once a CD-R disc is finished recording, the CD will be able to be
used in
any standard CD-ROM, CD-R, CD-RW, or DVD drive. Although, there were
issues
with the first revision DVD drives reading CD-R discs.
CD-Rs are a
low cost solution for backing up software. Each
CD-R often only costs a few cents (as of 2010 around 17-cents a disc)
and are
capable of holding up to 650 MB (74 minutes of music) or 700MB (80
minutes of
music). Although these are still a very popular solution for backing up
data,
more users are turning to USB thumb drives to backup and transfer their
data.
Jump drive and USB Flash Drive
Alternatively
referred to as a USB flash drive, data
stick, pen drive, keychain drive and thumb drive, a jump drive is a
portable
drive that is often the size of your thumb that connects to the computer
USB
port. Today, flash drives are available in sizes such as 256MB, 512MB,
1GB,
5GB, and 16GB and are an easy way to transfer and store information.
In the
picture to the right, is an example of the SanDisk
Cruzer Micro 16GB flash drive and a good example of what many flash
drives look
like. As can be seen in this picture, the drive has a small casing that
stores
the flash memory connected to a USB connection that is plugged into the
USB
port on your computer.
Unlike a
hard drive the flash drive only contains an
integrated circuit memory board capable of storing information and has
no
movable parts.
The term flash drive may also be used
to describe a SSD.
Zip drive
Hardware
data storage device developed by Iomega that
functions like a Standard 1.44" floppy drive. What makes the Iomega zip
drive unique is its capability to hold up to 100 MB of data or 250 MB of
data
on new drives. Iomega Zip Drives became very popular in late 1990s,
however,
became less popular as users needed larger storage capabilities. This
drive was
later replaced by larger and cheaper CD-R and CD-RW drives and discs. In
the
picture to the right, is an example of an Iomega Zip diskette. This
diskette is
bigger than the standard floppy diskette and is made out of a much
harder
plastic.
Hard disk drive
A hard disk drive (HDD) is a data
storage device used for
storing and retrieving digital information using rapidly rotating disks
(platters) coated with magnetic material. An HDD retains its data even
when
powered off. Data is read in a random-access manner, meaning individual
blocks
of data can be stored or retrieved in any order rather than
sequentially. An
HDD consists of one or more rigid ("hard") rapidly rotating disks
(platters) with magnetic heads arranged on a moving actuator arm to read
and
write data to the surfaces.
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