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Solid state disc drive

Computers have a (secondary) storage device called a disk drive, It is where all your apps are stored. There are currently two types of storage device, the magnetic hard disk drive and the solid state disk drive.

A computer (unopened)
Picture
A computer (opened) - SSD shown
Picture
SSD removed
Picture

How does a solid state drive work?

  1. When you take the cover off a solid state drive/USB memory stick, you will see NAND flash memory cells (as below)
  2. Inside NAND flash memory cells are billions of "Floating gate transistors" arranged as a grid
  3. Floating gate transistors (are a bit like cups that) trap electrons in a "pool"
Opening data from a SSD
  1. When opening data from a SSD, if one floating gate transistor contains electrons, the computer reads it as a "zero". If another floating gate transistor is empty of electrons, the computer read it as a "one"
Saving to a SSD
  1. When saving data to a SSD, an electrical charge (from the computer) is used to create binary string which is sent to the SSD. A charge causes electrons to move between two pools
Deleting/erasing data from a SSD 
  1. To erase data from a SSD, a high voltage removes electrons from the pools.

​NAND flash memory magnified

NAND flash (black chip)
​
Picture
NAND magnified (one small section shown)
Picture
NAND magnified further to show one of billions of the floating gate transistors
Picture

Examples of solid state media

Picture
Memory card and and smart phone memory
Picture
USB memory stick
Picture
Tablet computer memory
Loading Solid state drive
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  • Edexcel GCSE CS
    • Past papers >
      • 2020 Current spec (coming soon) >
        • Programming Language Subset (PLS)
      • Old 2016 SPEC >
        • Paper 1 (specimen1)
        • Paper 1 (specimen2)
        • Paper 1 (2018)
        • Paper 1 (2019)
        • Paper 2 (specimen1)
        • Paper 2 (2018)
        • Paper 2 (2019)
      • OLD 2013 SPEC >
        • Sample assessment 1 (old spec)
        • Sample assessment 2 (old spec)
        • June 2017 (old spec)
        • June 2016 (old spec)
        • June 2015 (old spec)
    • Paper 1 (by topic) >
      • Algorithms
      • Application software
      • Ascii
      • Binary
      • Cache
      • Client Server
      • Cloud
      • Compression
      • Computational thinking
      • CPU
      • Cyber security
      • Database
      • Fetch decode execute cycle
      • Embedded system
      • Encryption
      • File size
      • Flow chart
      • Hexadecimal
      • High Level language
      • ISP/Internet
      • Logic
      • Magnetic HDD
      • Networking
      • Open source
      • Operating system
      • Peer to peer
      • Images (Data representation)
      • Protocols
      • RAM
      • ROM
      • Run length encoding
      • Simulation software
      • Solid state HDD
      • Sound
      • Stored program concept
      • Utility software
    • Curriculum >
      • Binary
      • Hex
      • Data Representation
      • Compression
      • Encryption
      • What is a computer
      • How does a computer work
      • Hardware
      • Operating system
      • The CPU
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      • Emerging trends
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