1.3 Storage Flashcards
What is secondary storage?
Storage location which permanently stores OS, programs and data.
What is the purpose of secondary storage?
To use the data later.
To use the software.
To interact with the computer.
How do optical drives work?
A laser light marks patterns into the disk which represent 0’s and 1’s.
Then the laser light detects where the marks are and translates them into a readable format.
How do magnetic drives work?
They read / write across the medium and change how magnetised that part of the medium is.
Each level of magnetism represents 0’s and 1’s.
What are the properties (made up of and characteristics) of solid state/flash drives?
They are made up of silicon microchips (switches).
They are fast but the most expensive and have no moving parts.
On = 1.
Off = 0.
How much data does one character represent?
1 byte per character.
What percentage overheads do you need when calculating data?
10%.
But only use if the question specifies.
True/False: Data can be stored on secondary storage devices
True
What are the three main types of storage device?
Magnetic discs, optical discs and solid-state (flash) memory
Data and programs are stored temporarily/permanently on secondary storage devices
permanently
Why must data stored on secondary storage devices be loaded into main memory?
They must be transferred to main memory because the CPU cannot access them directly
Secondary storage devices can be used to transfer what between computers?
Stored data
What is magnetic storage often used in?
Hard disc drives and digital tape drives
What does HDD stand for?
Hard Disc Drive
What are HDDs and digital tape drives often used for?
Backup up large computer systems
What do magnetic discs consist of?
Stacks of non-removable discs coated with magnetic materials
How is data encoded with magnetic storage?
As opposing magnetic polarities on the surface of the disc. Electromagnets in the read/write heads read and write data
With magnetic storage, electromagnets in the read/write heads…
read and write data
The cost of magnetic storage is very high/low
low
True/False: Hard disc drives in budget laptops have capacities of at least 1 terabyte
True
CDs, DVDs and Blu-ray discs are all examples of what type of storage media?
Optical
List DVD, CDs and Blu-ray discs in the order of how much data they can store up to, from smallest to largest
CDs, DVDs and Blu-ray discs
What do optical discs use to read and write data?
A laser
With optical discs, data is encoded as a…
series of pits in a spiral track, running from the inside to the outside of the disc
True/False: With optical discs, data is is encoded as a series of pits in a spiral track, running from the outside to the inside of the disc
False, the pits run from the inside to the outside of the disc, not the other way round
CD, DVD and Blu-ray drives write and read data onto discs using…
light from lasers
Unlike magnetic and optical storage, there are/are no moving parts in solid-state devices
are no
True/False: There are moving parts in solid state devices
False, there are not
Solid-state memory is made of what type of memory?
Flash memory
Flash memory is volatile/non-volatile storage
non-volatile
True/False: Flash memory can be electrically erased and reprogrammed
True
Flash memory uses arrays of…
transistors (switches)
How many states can transistors operate in?
2
What are the two states that transistors can operate in?
0 and 1
How are transistors switched between their two states?
Using electrical signals
How is data encoded with flash memory?
As sets of binary digits
True/False: 8 GB of solid-state storage require 32 billion transistors
True
In what devices is solid-state memory used for data storage?
Portable devices such as cameras and mobile phones
What does SSD stand for?
Solid State Drive
True/False: SSDs can provide secondary storage instead of magnetic discs
True
What does SD stand for?
Secure digital
In what devices are SD and microSD cards used?
Portable devices such as phones, cameras and tablets
USB flash drives are convenient compact forms of flash memory for…
sharing and transferring data
The different storage devices have different/the same properties
different
What is the capacity of magnetic drives like?
Very large
What is the capacity of optical drives like?
Low
What is the capacity of solid state drives like
Moderate
What is the speed of magnetic drives like?
Fast
Why is magnetic storage fast?
Data can be read instantly from any part of the disc and can find and supply required data in milliseconds
What is the speed of optical drives like?
Slow
What is the speed of solid state drives like?
Very fast - can access data in nanoseconds
What is the cost of magnetic drives like?
Very low
Magnetic drives storing terabytes of data are common in…
most home computers
What is the cost of optical drives like?
Very low
What is the cost of solid state drives like?
More expensive than magnetic drives and optical devices
Solid state storage is relatively old/new technology
new
As solid state storage is developed, storage capacity is rapidly increasing/decreasing and the cost is increasing/decreasing
increasing, decreasing
The different secondary storage each have benefits and drawbacks depending on…
the situation
What is the portability of magnetic drives like?
Not very portable
Why are magnetic drives not very portable?
Physical knocks may cause the read/write heads to hit the discs and corrupt data
How portable are optical storage devices?
More portable than a hard disc but discs are relatively large
How portable is solid-state storage?
Very portable. Small solid-state storage devices can be fitted inside cameras and mobile phones
What is the durability of magnetic drives like?
Very durable
What is the durability of optical storage like?
Low because they are easily scratched and data can be corrupted
Data stored on optical devices can/cannot be overwritten
cannot
With data stored on optical devices, what happens over time?
It can degrade
What is the durability of solid state devices like?
There is a limited number of erase/write cycles
There is a limited/unlimited amount of erase/write cycles with solid-state storage
limited
How reliable is magnetic storage?
Very reliable
How reliable is optical storage?
Very reliable if they are not scratched
How reliable is solid state storage?
Very reliable and data is not affected by magnetic fields (as they are in magnetic drives)
True/False: Data in magnetic drives can be affected by magnetic fields
True
True/False: Data in solid state storage can be affected by magnetic fields
False
List 3 benefits of magnetic storage
Any 3 from very large capacity, fast, very low cost, very durable and very reliable
What is the disadvantage of magnetic storage?
It is not very portable as physical knocks may cause the read/write heads to hit the discs and corrupt data
List 2 benefits of optical storage
Any 2 from it is very reliable, more portable than a hard disc drive and very low cost
Give 2 disadvantages of optical storage
Any 2 from low capacity, slow and not very durable as easily scratched and data can be corrupted
List 3 benefits of solid state storage
Any 3 from very portable, very reliable, very fast and pretty good capacity & durability
What is the disadvantage of solid state storage?
It is very expensive
