Unit 1.3 Storage

Unit 1.3 Storage

1. Types of storage

   • Optical
     • A laser light creates marks in a pattern on the disk. A laser light detects where the marks are and translates them into a readable format.
     • eg. Blu Ray, DVD ROM ,CD ROM
     • Durable through shock and water damage. Low cost per GB. Portable.
     • Slow to write to. Not as much capacity. Can be easily scratched and damaged.
   • Magnetic
     • eg. Hard disk drive, tape drives
     • Read/Write move across the medium and change how magnetised that part of the medium is. One level of magnetism could be a 1 and a second could be a 0.
     • Not very expensive. Portable and durable.
     • Don't have a lot of storage space. Slow and not too reliable.
   • Solid State
     • Made of microchip switches, the switches determine whether a 1 or a 0 is stored.
     • eg. USB memory stick, SD card, solid state drive
     • No moving parts, uses flash memory, removable storage
     • Flash memory
       • Non-volatile storage medium that can be electronically erased and reprogramed
       • Inserted part can become damaged and its more expensive than other mediums

2. 1 million bytes in a MB eg. 3MB = 3 million bytes

3. Secondary storage is needed to back up data and for larger amounts of data