Memory and Storage

Memory and Storage

1. Secondary Storage

   • Long term storage of:
     • Data
     • Files
     • Software
     • Operating Systems
   • Non-volatile
     • Does not get deleted when computer is powered down

2. Optical Storage

   • Surface of a CD is covered in microscopic dots
   • A laser skims over the surface and picks up the stored data
   • Laser burns pits into the disc to represent binary values
     • pit = 0 land = 1
   • Generally doesn't have much storage
     • Ordered Smallest To Largest
     • CD
       • 650-700 MB of storage
       • DVD
         • 4.7 - 8.5 GB of storage
         • Blue-Ray
           • 50 GB of storage

3. Read Only Memory

   • ROM
   • Retains information even when computer has been powered down
     • Non-volatile
       • Does not get deletes when computer is powered down
   • Encoded by the manufacturer
   • Stores basic information:
     • Load the operating systems into RAM
     • Power up information
   • Can not be re-written, can only be read
   • Directly connected to the CPU through busses

4. Random Access Memory

   • Hold data and instructions that the computer is currently using
   • Acts as a buffer to the secondary memory
   • RAM
   • Data is lost when computer powers down or resets
     • Volatile
       • Does get deletes when computer is powered down
   • When computer is left on for some time and lots being done, the computer slows down as RAM is full and working backwards to get the data back into secondary storage
   • Takes data from the programs out of secondary storage and moves it to be closer to the CPU and faster to access

5. Virtual Memory

   • Only used if RAM becomes full
   • Small section of Secondary Storage
   • Back up RAM designated by the operating system at the time it is needed
   • Temporary
     • Used until RAM becomes free again

6. Flash Memory

   • AKA: Flash Storage
   • Easy and fast information storage in:
     • computers
       • digital cameras
         • video game consoles
   • Non-volatile
     • Does not get deletes when computer is powered down
   • Erases data in units called blocks
   • Very common form of storage
   • re-writes data at byte level

7. Solid State Storage

   • USB
     • Universal Serial Bus
   • No moving parts
   • stores data using circuit chips
   • SSD