1.1.3.2 The Use of Storage

Question 1

What is a Storage Device?

Answer 1

• Any medium on which data can be stored even when powered off.

Question 2

What is Magnetic Storage?

Answer 2

• They are devices which store information magnetically
• A high capacity and low cost means of storage.
• Relies on the polarization of magnetic particles to store bits on a magnetic material which is typically moved mechanically.
• Represent binary information using two magnetic states: polarized and unpolarized.
• If a portion of magnetic material is polarized, all magnetic poles align and can be read by a read/write head passing over the region.
• If an area is not polarized, magnetic poles are randomly scattered and produce a different reading on a read/write head.
• These two states can represent 1 and 0, allowing any information to be represented in binary form.

Question 3

What are some types of Magnetic Storage?

Answer 3

• Hard Disk Drive
• Magnetic Tape
• Floppy Disk

Question 4

What is a HDD?

Answer 4

• Hard Disk Drive
• They typically have high capacities of between 500GB and 5TB.
• They work by rotating magnetic platters at high speeds under a read/write head on an actuating arm.
• The combination of the arm and rotating platter allows the read/write head to access any part of the platter.
• Most HDDs will have multiple platters stacked on top of each other to maximize storage capacity.
• Disadvantages of HDDs include their somewhat slow data transfer speeds and their tendency to become damaged by movement.
• The combination of brittle platters and moving parts results in a delicate device.

Question 5

What is Magnetic Tape?

Answer 5

• First used to record computer data in the 1950s, magnetic tape was a popular storage medium right through to the 1980s.
• Wound onto reels, long stretches of tape were passed through readers which would check the polarity of the tape and read off a binary value.
• Tape was a bulky way to store data, and although improvements were made by reducing the width of the tape and writing in diagonal lines as opposed to horizontal tracks, the technology was superseded by more modern technology like ROM cartridges.

Question 6

What is a Floppy Disk?

Answer 6

• A floppy disk comprises a thin magnetic disk - which would have originally been flexible, hence the name - enclosed in plastic to protect the disk from dust and dirt.

They were incredibly portable, thanks to their thin size and low weight, so became popular for exchanging small amounts of data - in a similar way to how USB flash drives are used today.

Floppy disks had a typical storage capacity of 1MB although some later versions boasted as much as 200MB.

Question 7

What is Flash Storage?

Answer 7

• A solid state technology that stores data on a collection of memory chips.
• No moving parts as data is accessed by software.
• Flash storage is fast and compact.
• The technology makes use of silicon semiconductors forming the logic gates NAND and NOR to store electrical charge in one of two states: high or low.
• These two states represent the binary values True and False, which can be used to represent information.
• Information is stored in blocks, which are combined to form pages.
• The preferred logic gate used for storing small quantities of data, such as code to be executed, is NOR.
• For larger files, like photos and videos, NAND is the preferred technology.
• Flash memory can be erased and reprogrammed electronically, and is non-volatile, meaning it stores its data even when power is lost.
• These features make SSDs a good replacement for HDDs as they have the same functionality but improved performance.
• Although flash memory is similar to RAM, the two differ in that RAM is volatile - loses its content with loss of power - while flash memory retains its information.
• As a general rule, flash memory is more expensive per gigabyte than other methods of data storage, like magnetic and optical.

Question 8

What is a type of Flash Storage?

Answer 8

• Solid State Drive

Question 9

What is SSD?

Answer 9

• Solid State Drive
• Solid State Drives are currently one of the most popular forms of data storage.
• They are extremely light and portable, while having no moving parts - this makes them much more resistant to damage from movement than hard disk drives, which are packed with moving parts.
• Furthermore, SSDs are renowned for their high data transfer rates.
• The primary disadvantage of SSDs is their cost, which continues to decrease as they become more common.
• Another disadvantage is their limited lifespan.
• Every time a page is written to, the voltage required to write to it increases.
• Over time, this required voltage will become too high for the page to be written to.

Question 10

What is Optical Storage?

Answer 10

• Data is stored in the reflectivity of a surface, and is read and written to by a laser.
• Optical devices are read from and written to using lasers.
• Binary information is represented by portions of the disc which either reflect or scatter the incident laser light written in spiral tracks on the disc’s surface.
• The portions which are recessed, called pits, scatter light whereas the flat portions, called lands, reflect light.
• Pits represent a 0 and lands represent a 1.

Question 11

What are 3 types of Optical Storage?

Answer 11

• Compact Disc
• Digital Versatile Disc
• Blu-Ray

Question 12

What is a CD?

Answer 12

• Compact Disc
• They use optical technology to store small quantities of information.
• Most commonly used for audio files, CDs can also be used to store text and digital images.
• CDs are small, thin and light which makes them very portable.
• However, They are easily damaged by scratches, have limited storage capacity and relatively slow transfer speeds.
• Varieties of CD include:
  CD-R:
  Which can only be written to once

CD-RW:
Which can be written to more than once

And CD-ROM:
Which is written to during production and can then only be read from.

Question 13

What is a DVD?

Answer 13

• Digital Versatile Disc
• Similar to CDs, DVDs are also optical devices.
• They have a higher storage capacity than CDs, making them suited to storing digital videos which require more storage space than audio files or photos.

Question 14

What is Blu-Ray Disc?

Answer 14

• Blu-Ray discs have more than five times as much storage than traditional DVDs, making them useful for storing high-resolution films.