secondary storage

• label best to worst (1-3) in terms of

  A) 1

  B) 2

  C) 3

  D) 1

  E) 2

  F) 3

  G) 1

  H) 2

  I) 3

  J) 1

  K) 2

  L) 3

  M) 1

  N) 2

  O) 3

  P) 1

  Q) 2

  R) 3

  
• • Cost - what is the cost per gigabyte (GB)?
  • Capacity - how much data can the medium hold?
  • Speed of access - how quickly can data be transferred to and from the medium? usually measured in megabytes per second.
  • Portability - how portable is the medium? Does it need to be portable?
  • Durability - how robust is the medium, and how robust will it need to be? Is it affected by extreme temperature?, what if it gets wet?, what if it is placed next to a large loudspeaker?
  • Reliability - how resilient and long-lasting is the medium?
• Why do you need secondary storage?

  • A computer needs secondary storage for long term storage of programs and data that are currently not in use
  • Secondary storage is needed as ROM is read only and RAM is volatile
  • Secondary storage holds the programs and data whilst the computer is turned off (non-volatile)
  • Performance of secondary storage is slower than primary storage but capacity is much higher which makes it perfect for backup & archive of data files
• Not all computers require secondary storage. Embedded computers, such as those found in a digital watch or central heating system, do not need to store data when the power is turned off. The instructions needed to run them are stored in ROM and any user data is held in RAM.
• Magnetic devices

  • Magnetic storage is a type of non-volatile media that uses magnets (polarity) to store binary 0s and 1s
  • can contain terabytes (TB) of data.
  • As the disk spins, a read/write head moves across its surface
  • They are vulnerable to magnetic fields - A strong magnet might possibly erase the data the device holds.

  A) high

  B) low

  C) moderate

  D) moving parts

  E) damaged

  F) dropped

  G) heavy

  H) bulky

  I) convenient

  J) mechanical failure

  K) loud

  L) spinning disks

  
• Optical devices

  Optical storage uses lasers to burn the surface of a disk, creating pits and lands suitable for storing binary 0s and 1s

  optical media types:

  • ROM media have pre-written data, cant be overwritten. Music, films, software, games often distributed this way.
  • R media r blank. optical device writes data to them by shining a laser onto the disc. only written to once, but read many times.
  • RW similar to R, but can be written to more than once.

  A) low

  B) moving parts

  C) small

  D) silent

  E) low

  F) slow

  G) scratches

  
• Solid state devices

  • Solid state storage is a type of non-volatile media that uses electronic circuits to store binary 0s and 1s.
  • expensive = smaller in capacity
  • Solid state devices require little power, making them ideal for portable devices where battery life is a big consideration

  A) high

  B) fast

  C) moving parts

  D) small

  E) silent

  F) high