DATA STORAGE DEVICES
YUKI NAKA FLORES
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic
storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust
particles. They are read and written by a floppy disk drive (FDD).
Floppy disks, initially as 8-inch (200 mm) media and later in 5.25-inch (133 mm) and 3.5-
inch (89 mm) sizes, were a ubiquitous form of data storage and exchange from the mid-
1970s well into the first decade of the 21st century.
By 2010, computer motherboards were rarely manufactured with floppy drive support; 3
1⁄2" floppies could be used with an external USB drive, but 5 1⁄4", 8", and non-standard
drives could only be handled by old equipment.
While floppy disk drives still have some limited uses, especially with legacy industrial
computer equipment, they have been superseded by data storage methods with much
greater capacity, such as USB flash drives, portable external hard disk drives, optical
discs, memory cards, and computer network.
A DVD-RW disc is a rewritable optical disc with equal storage capacity
to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in
November 1999 and has been approved by the DVD Forum. The
smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.
The primary advantage of DVD-RW over DVD-R is the ability to erase
and rewrite to a DVD-RW disc. According to Pioneer, DVD-RW discs
may be written to about 1,000 times before needing replacement. DVD-
RW discs are commonly used to store data in a non-volatile format,
such as when creating backups or collections of files. They are also
increasingly used for home DVD video recorders. One benefit to using
a rewritable disc is if there are writing errors when recording data, the
disc is not ruined and can still store data by erasing the faulty data.
One competing rewritable format is DVD+RW. Hybrid drives that can
handle both, often labeled "DVD±RW", are very popular due to the lack
of a single standard for recordable DVDs.
The recording layer in DVD-RW and DVD+RW is not an organic dye,
but a special phase change metal alloy, often GeSbTe. The alloy can
be switched back and forth between a crystalline phase and an
amorphous phase, changing the reflectivity, depending on the power of
the laser beam. Data can thus be written, erased and re-written.
A tape drive is a data storage device that reads and
performs digital recording, writes data on a magnetic tape.
Magnetic tape data storage is typically used for offline,
archival data storage. Tape media generally has a
favorable unit cost and long archival stability.
A tape drive provides sequential access storage, unlike a
disk drive, which provides random access storage. A disk
drive can move to any position on the disk in a few
milliseconds, but a tape drive must physically wind tape
between reels to read any one particular piece of data. As
a result, tape drives have very slow average seek times.
For sequential access once the tape is positioned,
however, tape drives can stream data very fast. For
example, as of 2010[update] Linear Tape-Open (LTO)
supported continuous data transfer rates of up to 140
MB/s, comparable to hard disk drives.
Un CD-R es un formato de disco compacto grabable.(Compact Disc
Recordable = Disco Compacto Grabable). Se pueden grabar en varias
sesiones, sin embargo la información agregada no puede ser borrada
ni sobrescrita, en su lugar se debe usar el espacio libre que dejó la
sesión inmediatamente anterior.
Actualmente las grabadoras llegan a grabar CD-R a 52x, unos 7800
Para muchos ordenadores es difícil mantener esta tasa de grabación y
por ello la grabadoras tienen sistemas que permiten retomar la
grabación ante un corte en la llegada de datos.
La capacidad total de un CD-R suele ser:
• 650 MB = 681,57 millones de bytes
• 700 MB = 734 millones de bytes. El más común.
• 800 MB = 838 millones de bytes.
• 900 MB = 943 millones de bytes.
A CD-RW (Compact Disc-ReWritable) is a rewritable optical disc. It was introduced in
1997, and was known as "CD-Writable" during development. It was preceded by the
CD-MO, which was never commercially released.
CD-RW disc require a more sensitive laser optics. Also, CD-RWs cannot be read in
some CD-ROM drives built prior to 1997. CD-ROM drives will bear a "MultiRead"
certification to show compatibility. CD-RW discs need to be blanked before reuse.
Different blanking methods can be used, including "full" blanking in which the entire
surface of the disc is cleared, and "fast" blanking in which only meta-data areas are
cleared: PMA, TOC and pregap, comprising a few percent of the disc. Fast blanking is
much quicker, and is usually sufficient to allow rewriting the disc. Full blanking removes
traces of the former data, often for confidentiality. It may be possible to recover data
from full-blanked CD-RWs with specialty data recovery equipment; however,
this is generally not used except by government agencies due to cost.
CD-RW also have a shorter rewriting cycles life (ca. 1,000) compared to virtually all of
the previously exposed types storage of media (typically well above 10,000 or even
100,000), something which however is less of a drawback considering that CD-RWs
are usually written and erased in their totality, and not with repeated small scale
changes, so normally wear leveling is not an issue.
Their ideal usage field is in the creation of test disks, temporary short or mid-term
backups, and in general, where an intermediate solution between online and offline
storage schemes is required.
A zip disk is a computer hardware device that
stores data. A zip disk drive is somewhat like
floppy disk drive, only that the size of disks
inserted into the devices are different. Where a
normal floppy disk can hold about 1.44
megabytes of data, a zip disk can hold around
100 megabytes of data. This means that a zip
disk can hold a lot more data which is useful in
today's computer market where software
applications and files are becoming bigger.
Files such as mp3 music files usually need to
saved on 2 or more floppy disks whereas a zip
disks can hold numerous mp3 files.
Mini CDs, or “pocket CDs” are CDs with
a smaller diameter and one third the
Mini CDs, or “pocket CDs” are CDs with
a smaller diameter and one third the
Flash memory is a non-volatile computer
storage chip that can be electrically erased
and reprogrammed. It was developed from
EEPROM (electrically erasable
programmable read-only memory) and
must be erased in fairly large blocks before
these can be rewritten with new data. The
high density NAND type must also be
programmed and read in (smaller) blocks,
or pages, while the NOR type allows a
single machine word (byte) to be written or
Secure Digital (SD) is a non-volatile memory card format developed by the SD Card
Association (SDA) for use in portable devices. The SD technology is used by more than
400 brands across dozens of product categories and more than 8,000 models.
SD comprises several families of cards: the original, Standard-Capacity (SDSC) card,
a High-Capacity (SDHC) card family, an eXtended-Capacity (SDXC) card family, and
the SDIO family with input/output functions rather than just data storage.
SD also comprises three different form factors: the original size, the "mini" size, and the
"micro" size (see illustration). Electrically passive adaptors allow the use of a smaller
card in a host device built to hold a larger card. There are many combinations of form
factors and device families.
Host devices that comply with newer versions of the specification provide backward
compatibility and accept older SD cards, but older host devices do not recognize newer
cards. The SDA uses several trademarked logos to enforce compliance with its
specifications and assure users of compatibility. This article explains several factors
that can prevent the use of a newer SD card:
• A newer card may offer greater capacity than the host device can handle.
• A newer card may use a file system the host device cannot navigate.
• Use of an SDIO card requires the host device be designed for the input/output
functions the card provides.
• The organization of the card was changed starting with the SDHC family.
• Some vendors produced SDSC cards above 1 GB before the SDA had standardized a
method of doing so.
TRANSFLASH O MICRO
microSD is a kind of removable flash memory card used for storing information. SD is an abbreviation
of Secure Digital. The cards are used in cellular phones. They are also used in newer types of
handheld GPS devices, portable media players, digital audio players, expandable USB flash memory
drives, Nintendo DS flashcards, and digital cameras.
It is the smallest memory card that can be bought; at 15 mm × 11 mm × 1 mm (about the size of a
fingernail), it is about a quarter of the size of a normal-sized SD card. There are adapters that make
the small microSD able to fit in things that have slots for standard SD, miniSD, Memory Stick Duo and
even USB cards. But, not all of the different cards can work together. Many microSD cards sold on the
internet and in stores have a standard SD adapter, so that people can use them in things that take
standard SD but not microSD cards.
TransFlash and microSD cards are the same (they can be used in place of each other), but microSD
has support for SDIO mode, so that non-memory cards like Bluetooth, GPS, and Near Field
Communication devices to use the card also.
Some people have a hard time knowing the difference between the microSD and the newer
microSDHC format. The SD and SDHC act the same, but not all devices are able to be used with the
newer format. This is even true with devices that have been made by SanDisk like their e200 series of
MP3 players. Using 3rd party firmware, SDHC reading can sometimes be done.
TransFlash cards are sold in 16MB and 32MB sizes. microSD cards are sold in many sizes, from 64
MB to 2 GB, while microSDHC cards are sold in sizes between 4 GB to 64 GB. (This is the biggest
microSD card so far, and the microSDHC format can not store anything past that amount. microSD
cards with even more storage will be in microSDXC format.)
CompactFlash (CF) is a mass storage device format used in portable electronic
devices. Most CompactFlash devices contain flash memory in a standardized
enclosure. The format was first specified and produced by SanDisk in 1994. The
physical format is now used for a variety of devices.
CompactFlash became the most successful of the early memory card formats,
surpassing Miniature Card, SmartMedia, and PC Card Type I in popularity. Subsequent
formats, such as MMC/SD, various Memory Stick formats, and xD-Picture Card offered
stiff competition. Most of these cards are smaller than CompactFlash while offering
comparable capacity and speed. Proprietary memory card formats for use in
professional audio and video, such as P2 and SxS, are physically larger, faster, and
CompactFlash remains popular and is even supported in some new devices. For
example, in 2008, Sony chose CompactFlash as the recording medium for the HVR-
MRC1K tapeless video recorder over smaller MemoryStick cards or expensive SxS
cards. In 2010, Canon chose CompactFlash as the recording medium for its new
professional high-definition video cameras, and Ikegami devices record digital video
onto CompactFlash cards through an adaptor.
In November 2010, Sandisk, Sony and Nikon proposed a next generation card format
to the CompactFlash Association which would come in a similar form factor as
CF/CFast but be based on PCI Express instead of Parallel ATA or SATA.  The new
format is targeted at high-definition camcorders and high-resolution digital photo
cameras, would offer a target read and write speeds of 1 Gbps (125 Mbyte/s) and
storage capabilities beyond 2 TiB, and is not backward compatible with either
CompactFlash or CFast. The XQD card format has been announced by the
CompactFlash Association in December 2011.
The MultiMediaCard (MMC) is a flash memory memory card standard. Unveiled in
1997 by SanDisk and Siemens AG, it is based on Toshiba's NAND-based flash
memory, and is therefore much smaller than earlier systems based on Intel NOR-based
memory such as CompactFlash. MMC is about the size of a postage stamp: 24 mm ×
32 mm × 1.4 mm. MMC originally used a 1-bit serial interface, but newer versions of the
specification allow transfers of 4 or 8 bits at a time. It has been more or less
superseded by SD (Secure Digital) card, but still sees significant use because MMCs
can be used in most devices that support SD cards.
Typically, an MMC is used as a storage medium for a portable device, in a form that
can easily be removed for access by a PC. For example, a digital camera would use an
MMC for storing image files. With an MMC reader (typically a small box that connects
via USB or some other serial connection, although some can be found integrated into
the computer itself), a user could copy the pictures taken with the digital camera off to
his or her computer. Modern computers, both laptops and desktops, often have SD
slots, which can additionally read MMCs if the operating system drivers support them.
MMCs are available in sizes up to and including 128 GB. They are used in almost
every context in which memory cards are used, like cellular phones, digital audio
players, digital cameras and PDAs. Since the introduction of Secure Digital card few
companies build MMC slots into their devices (an exception is some mobile devices like
the Nokia 9300 communicator, where the smaller size of the MMC is a benefit), but the
slightly thinner, pin-compatible MMCs can be used in almost any device that supports
SD cards if the software/firmware on the device supports them.
SmartMedia is a flash memory card
standard owned by Toshiba, with
capacities ranging from 2 MB to 128
MB. SmartMedia memory cards are no
This table provides summary of
comparison of various flash memory
cards, as of 2011[update].
is a flash memory card format, used
mainly in older digital cameras. xD
stands for Extreme Digital.
xD cards are available in capacities of
16 MiB up to 2 GiB.
A USB flash drive is a data storage device that
includes flash memory with an integrated Universal
Serial Bus (USB) interface. USB flash drives are
typically removable and rewritable, and physically
much smaller than a floppy disk. Most weigh less
than 30 g. As of January 2012 drives of 256GB
were available, 512GB and 1 terabytes (TB) drives
were in planning,  and storage capacities as large
as 2 terabytes are planned, with steady
improvements in size and price per capacity
expected. Some allow up to 100,000 write/erase
cycles (depending on the exact type of memory chip
used) and 10 years shelf storage time.
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