1.3 Storage COMPLETE
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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