1.3 storage

1.3 storage

1. Keywords

   • secondary storage
   • optical
   • magnetic
   • solid state
   • durabiltly
   • reliability
   • portability
   • capacity
   • speed
   • Storage
   • characteristic
   • estimate
   • overheads

2. secondary storage

   • long term storage of data, files and information
   • we need to store this so we can access it later and to use it later
   • we need secondary storage so programs wont reinstall every time we use it
   • when a device is not constantly connect connected to a computer
   • They are needed to back up data and for larger storage capacity
   • Advamtages
     • Memory is non-volitale
     • Data is not lost

3. Types of storage

   • Optical
     • a laser light creates mark in a pattern on the disk
     • advantages of optical
       • cost
       • portability
       • durability
       • capacity
     • Most suitable for distributing a movie
       • storage device for distributing for a movie is a DVD
   • Magnetic
     • read/write move across the medium and change how magnetised that part of the medium is
     • Advantages of magnetic
       • capacity
       • speed
       • portability
       • reliability
       • cost
   • Solid State
     • Made of microchips
     • The state of the switches determine if a 1, or 0 is stored
     • Advantages of solid state
       • Portable
       • Durable
       • Fairly reliable

4. Characteristics of storage devices

   • Capacity
     • how much data will it store
   • speed
     • how fast can the data be accessed
   • Portability
     • how easy is it to move it from one place to another
   • Durability
     • how well does it last e.g if it was to be dropped
   • Reliability
     • how consistently does it perform
   • Cost
     • How much does it cost per KB, MB or GB

5. CD-ROM

   • Suitable for distributing music
     • Can be read by other devices
     • is read only, cant be over written
     • cheap to produce

6. Magnetic tape

   • Slow to write and read
   • all the data has to be read before the data you want