1. Magnetic Disk
Description:
The primary computer storage device. Like tape, it is magnetically recorded and can be re-recorded over and over. Disks are rotating platters with a mechanical arm that moves a read/write head between the outer and inner edges of the platter's surface. It can take as long as one second to find a location on a floppy disk to as little as a couple of milliseconds on a fast hard disk.
Advantage:
- The ability to write or record and read data very rapidly.
- Data that is no longer needed can be erased to make space available for new data.
- Data can be read directly from any part of the hard disc (random access).
- The access speed is about 1000 KB per second.
- Cheap to buy
Example:
- floppy disk (diskette)
- hard disk
- zip removable disk
- removable cartridge
2. Optical Disk
Description:
A disk drive that uses laser light or electromagnetic waves near the light spectrum as part of the process of reading and writing data. It is a computer's peripheral device, that stores data on optical discs. Some drives can only read from discs, but commonly drives are both readers and recorders. Recorders are sometimes called burners or writers.
Advantage:
- Have a relatively large storage capacity because the optical recording process can form
very small bits on the surface of the disk.
- Provides a minimum of 650 megabytes (MB) of data storage. A double-layered an
double-sided DVD optical disk holds up to 15.9 gigabytes (GB) of data.
- Storage capacity increases with each new generation of optical media. Emerging
standards, such as blu-ray, offer up to 27 gigabytes (GB) on a single-sided 12-
centimeter disc. In comparison, a diskette, for example, can hold 1.44 megabytes (MB).
- The greater control and focus possible with laser beams (in comparison to tiny magnetic
heads) means that more data can be written into a smaller space.
- By using multiple disk many images can be stored or archived.
- They are relatively tough, data stored on them is relatively impervious to most
environmental threats, such as power surges, or magnetic disturbances as long as
the surface does not get too scratched.
- Inexpensive to manufacture.
- Compact, lightweight, durable and digital.
Example:
- CD
- CD-ROM’s
- DVD
- Blu-ray disk
A disk drive that uses laser light or electromagnetic waves near the light spectrum as part of the process of reading and writing data. It is a computer's peripheral device, that stores data on optical discs. Some drives can only read from discs, but commonly drives are both readers and recorders. Recorders are sometimes called burners or writers.
Advantage:
- Have a relatively large storage capacity because the optical recording process can form
very small bits on the surface of the disk.
- Provides a minimum of 650 megabytes (MB) of data storage. A double-layered an
double-sided DVD optical disk holds up to 15.9 gigabytes (GB) of data.
- Storage capacity increases with each new generation of optical media. Emerging
standards, such as blu-ray, offer up to 27 gigabytes (GB) on a single-sided 12-
centimeter disc. In comparison, a diskette, for example, can hold 1.44 megabytes (MB).
- The greater control and focus possible with laser beams (in comparison to tiny magnetic
heads) means that more data can be written into a smaller space.
- By using multiple disk many images can be stored or archived.
- They are relatively tough, data stored on them is relatively impervious to most
environmental threats, such as power surges, or magnetic disturbances as long as
the surface does not get too scratched.
- Inexpensive to manufacture.
- Compact, lightweight, durable and digital.
Example:
- CD
- CD-ROM’s
- DVD
- Blu-ray disk
3. Flash Memory
Description:
Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM (Electrically Erasable Programmable Read-Only Memory) that is erased and programmed in large blocks; in early flash the entire chip had to be erased at once. Flash memory costs far less than byte-programmable EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile, solid-state storage is needed.
Advantage:
- Flash memory is non-volatile, which means that no power is needed to maintain the
information stored in the chip.
- Offers fast read access times (although not as fast as volatile DRAM memory used for
main memory in PCs)
- Better kinetic shock resistance than hard disks. - When packaged in a "memory card," it
is enormously durable, being able to withstand intense pressure, extremes temperature,
and even immersion in water.
Example:
- USB-drive
- Memory Card
- Smart Card
Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM (Electrically Erasable Programmable Read-Only Memory) that is erased and programmed in large blocks; in early flash the entire chip had to be erased at once. Flash memory costs far less than byte-programmable EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile, solid-state storage is needed.
Advantage:
- Flash memory is non-volatile, which means that no power is needed to maintain the
information stored in the chip.
- Offers fast read access times (although not as fast as volatile DRAM memory used for
main memory in PCs)
- Better kinetic shock resistance than hard disks. - When packaged in a "memory card," it
is enormously durable, being able to withstand intense pressure, extremes temperature,
and even immersion in water.
Example:
- USB-drive
- Memory Card
- Smart Card
4. Magneto-Optical Disk
Description:
A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. Both 130 mm and 90 mm form factors exist. The technology was introduced at the end of the 1980s. Although optical, they appear as hard disk drives to the operating system and do not require a special filesystem (they can be formatted as FAT, HPFS, NTFS, etc.).
Advantage:
- It can be rewritten repeatedly without significant damage to the disk.
- The cases provide dust resistance, and the drives themselves have slots constructed in
such a way that they always appear to be closed.
- Magneto-optical drives by default check information after writing it to the disc, and are
able to immediately report any problems to the operating system.
- Capacities ranged from 128MB to 2.3GB.
Example:
- Quadrilayer
- Magnetic Optical Disk’s
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