1.1.3 Input Output Storage (new) Flashcards
List examples of input devices.
Keyboards
Webcams
Magnetic stripe readers (read data on cards)
Barcode readers
List examples of output devices.
Speakers
Printers
Projectors
Monitors
Give an example of a device that is both input and output.
Touch screen.
What factors should be considered for input output devices?
Speed, accuracy, cost, relevance to task.
What is used to read and write to optical devices?
Lasers.
How is binary info represented on optical devices?
Pits and lands written in spiral tracks on the disc’s surface.
On optical devices, what do pits and lands do to light, and what do they represent?
Pit: Scatters light and represents 0
Land: Reflects light and represents 1
What does CD stand for?
Compact disc.
CDs store small quantities of information. What technology do they use to do this?
Optical technology.
What kind of file are CDs most commonly used for?
What could they also store?
Audio files.
Could also store text and digital images.
What are benefits of CDs?
Very portable due to being small, thin and light
What are downsides of CDs?
Limited storage capacity
Slow transfer speeds
What does DVD stand for?
Digital video disc / Digital versatile disc
How are DVDs different to CDs?
DVDs have higher storage capacity
DVDs are suited to storing digital videos.
How are BluRays superior to DVD?
More than five times as much storage than traditional DVDs. This is useful for storing high resolution films.
How do magnetic devices represent binary information?
Using two magnetic states: Polarised and unpolarised.
If an area is polarised, magnetic poles are aligned, representing 1.
If an area is unpolarised, magnetic poles are randomly scattered and produce different readings, representing 0.
What is the most common type of magnetic device?
HDD
How do HDDs work?
Magnetic platters rotate at high speeds under a read/write head on an actuating arm.
To maximise storage capacity, what do most HDDs have?
Multiple platters stacked.
What are advantages of HDD?
High capacities between 500GB and 5TB
What are disadvantages of HDD?
Somewhat slow data transfer speeds
Many moving parts introduces tendency to be damaged by movement.
How does magnetic tape work?
Long stretches of tape wound onto reels passed through readers.
The readers would check the polarity of the tape and read a binary value.
What is the downside of magnetic tape?
Space consuming way to store data.
What is the history of magnetic tape?
First used to record computer data in 1950s
Popular storage medium through to the 1980s
What is a floppy disk?
A thin magnetic disk enclosed in plastic (to protect it from dust and dirt)
Floppy disk advantage
Extremely portable due to thin size and low weight.
Floppy disk disadvantage.
Typical storage capacity of 1MB
What is good about flash storage?
- It is fast and compact.
- It can be erased and reprogrammed electronically.
- It is non volatile
What is the downside of flash memory?
More expensive per gigabyte than other methods of data storage.
What is good about SSD?
Extremely light and portable
No moving parts
Much more resistant to damage from movement than HDD
High data transfer rates.
What is bad about SSD?
Expensive
Limited life span: When a page is written to, the voltage required increases. Over time this becomes too high.
What are the two types of primary storage?
RAM and ROM
What is RAM?
A type of fast, volatile main memory used to store data and programs that the computer is currently using.
What is good about RAM?
Speeds up the computer’s execution due to higher speeds than flash memory.
What is bad about RAM?
More expensive per gigabyte than secondary storage devices.
What is ROM?
A non volatile memory that cannot be modified. Once it is programmed, the state of the memory cells inside does not change.
What is ROM useful for?
Storing fixed sequences of instructions like the bootstrap.
What is virtual storage?
Remote storage of information that can be accessed by any computer with access to the same system (eg over the internet).
What are examples of virtual storage?
Cloud storage services such as Google Drive
Networked storage used in offices and schools. (Network Allocated Storage)
Virtual storage is becoming popular as a result of what?
Increasing internet speeds.
Virtual storage is often an abstraction of what?
Multiple drives acting like one.
While virtual storage is convenient to access and share, what are disadvantages?
Limitations of a user’s network speed.
High costs.
