1.1.3: Input, Output, Storage Flashcards
How does Optical Storage work?
- Read from and written to using lasers
- Binary information is represented by portions of the disc that either reflect or scatter the incident laser written in the spiral tracks on the disc’s surface
What are Pits in terms of Optical Storage?
- Indented portions of the Optical disc
- Scatter light
- Represent 0
What are Lands in terms of Optical Storage?
- Flat portions of the Optical disc
- Reflect light
- Represent 1
What are CDs used for?
- Compact Disc
- Storing small quantities of information, commonly audio files, or text and digital images
What are DVDs used for?
- Digital Versatile Disc
- Higher storage capacity than CDs, making them suitable to storing digital videos which require more storage than audio files or photos
What are Blu-Rays used for?
- More than 5 times more storage than DVDs, making them useful for storing high resolution films
How does Magnetic Storage work?
- Devices storing information magnetically represent binary using polarised and unpolarised magnetic states
What is Polarised in terms of Magnetic Storage?
- All magnetic poles align and can be read by a read/write head passing over the region
What is Unpolarised in terms of Magnetic Storage?
- Magnetic poles are randomly scattered and produce a different reading on the read/write head
How do HDDs work?
- Typically have high capacities and 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
How does Flash Storage work?
- Fast and compact
- Make use of silicon semiconductors forming NAND and NOR logic gates to store electrical charge in one of two states to represent the binary values (high or low)
What are the benefits of Flash Storage?
- Can be erased and reprogrammed electronically
- Is non-volatile
What is NAND used for?
- For storing large files such as photos and videos
What is NOR used for?
- For storing small quantities of data, such as code to be executed
How do the CAPACITIES of the Storage types compare?
- OPTICAL: Up to roughly 50GB per disc
- MAGNETIC: Up to and including 15TB
- SSD: Up to about 4TB
How do the SPEEDS of the Storage types compare?
- OPTICAL: 50 MB/s
- MAGNETIC: 100 - 200 MB/s
- No problems in overwriting data
- SSD: Very fast when writing data (Up to 3.5 GB/s)
- Finite read - write cycles
How do the PORTABILITIES of the Storage types compare?
- OPTICAL: Very portable
- MAGNETIC (Internal): Not very portable
_ MAGNETIC (External: Very portable - SSD: Very portable unless inbuilt
How do the RELIABILITIES of the Storage types compare?
- OPTICAL: Very reliable
- Can last many years (Eventually degrade after 30+ years)
- MAGNETIC: Very reliable
- Can last many years, if not decades
- SSD: Very reliable due to lack of moving parts
How do the DURABILITIES of the Storage types compare?
- Depends how stored
- OPTICAL: Fairly durable
- Easily scratched if maltreated and are sensitive to overexposure to light
- MAGNETIC: Fairly durable but contain moving parts that can break easily
- SSD: Extremely durable due to lack of moving parts
How do the PRICES PER BIT of the Storage types compare?
- OPTICAL: Cheap
- MAGNETIC: Cheap
- SSD: Most expensive
How do the SIZES of the Storage types compare?
- OPTICAL: Small
- MAGNETIC: 2.5 - 3.5 Inches
- SSD: Range
How do RAM and ROM compare?
- RAM is Volatile: ROM is Non-Volatile
- RAM is Read - Write: ROM is Read Only
- RAM stores programs currently in use: ROM stores BOOTSTRAP and BIOS
What is Virtual Storage?
- Storing information remotely so that it can be accessed by a computer with access to the same system, for example over the internet
- Often an abstraction of multiple drives acting like one: Information stored on the Cloud is actually stored on 100s of hard drives or SSDs formatted to act as a single piece of storage
What are some examples of Virtual Storage?
- Cloud storage services
- Networked storage used in offices and schools
