Secondary Storage

• What type of storage do computers use to hold data that is being processed?

  Primary storage
• What is an example of primary storage?

  Random access memory (RAM)
• What is the nature of volatile memory?

  It loses its contents when the computer is switched off
• Why do general purpose computers need secondary storage?

  To store programs and data for later use or permanently
• What is the key fact about secondary storage?

  It is needed to store programs and data indefinitely
• What is the characteristic of secondary storage?

  It is non-volatile and long-term storage
• What happens to programs and data without secondary storage?

  All programs and data would be lost when the computer is switched off
• What is an example of a secondary storage device?

  Hard disk drive
• Why are different types of secondary storage devices suited to different applications?

  Because each type has its own characteristics
• What makes a hard disk drive suitable for everyday storage?

  It has a high capacity and reasonable access speed
• What is a characteristic of a USB memory stick?

  It is extremely fast and portable
• Do all computers require secondary storage?

  No, not all computers require secondary storage
• What type of computers do not need to store data when the power is turned off?

  Embedded computers
• Where are the instructions needed to run embedded computers stored?

  In read only memory (ROM)
• Where is user data held in embedded computers?

  In random access memory (RAM)
• What are the three types of secondary storage devices?

  Magnetic storage devices, optical storage devices, and solid state storage devices
• What is the key fact about data storage on secondary storage devices?

  • Data is stored in binary
• How do magnetic storage devices store data?

  They use magnetic fields to magnetise tiny sections of a metal spinning disk
• What does a magnetised section on a magnetic disk represent?

  A binary '1'
• What does a demagnetised section on a magnetic disk represent?

  A binary '0'
• What is the role of the read/write head in a magnetic disk drive?

  It moves across the disk to magnetise or demagnetise sections
• How is data accessed on a magnetic disk drive?

  By knowing the location of the data
• What are the two types of magnetic hard disk drives?

  Internal and external portable devices
• What is the primary use of tapes in data storage?

  For permanent storage of very large amounts of data
• How is data accessed on a tape?

  Sequentially (serially)
• What are the advantages of magnetic devices?

  They are low cost, high in capacity, and durable
• What are the vulnerabilities of magnetic devices?

  They can be damaged if dropped and are vulnerable to magnetic fields
• What technology do optical devices use to read data?

  A laser
• How is the surface of an optical disc divided?

  Into tracks with flat areas (lands) and hollows (pits)
• What does reflected light from lands on an optical disc represent?

  A binary '1'
• What does no reflection from pits on an optical disc represent?

  A binary '0'
• What are the types of optical media?

  • Read only (ROM) media: Data cannot be overwritten
  • Recordable (R) media: Can be written once, read many times
  • Rewritable (RW) media: Can be written to multiple times
• What is an example of a recordable optical disc?

  A CD-R
• What is an example of a read-only optical disc?

  A DVD-ROM
• What is solid state technology used in?

  Solid state drives (SSDs) and USB flash drives
• Why is it called solid state technology?

  Because it does not have any moving parts
• What are the advantages of solid state devices?

  They use low power, have high access speed, and are durable
• What is a common use for a USB flash drive?

  Moving small files from work to home