1.2

• what primary storages are there in a computer?

  Random access memory (RAM)

  Read only memory (ROM)

  Registers & Cache
• what is the purpose of primary storage?

  Holds data and instructions which the CPU needs access to while a computer is running
• Where can the CPU quickly access data from?

  from primary storage than secondary storage
• what is the purpose of the RAM?

  holds the operating system, programs and data that is in use by the CPU
• what is the purpose of ROM?

  Holds the first instructions for when the computer is first turned on (bootstrap) Programs may be stored in ROM in embedded systems.
• what is the meaning of volatile?

  contents lost when the power is turned off.
• Which is volatile, RAM or ROM?

  RAM
• which is larger, RAM or ROM?

  RAM is large in comparison to ROM
• why is virtual memory needed?

  when there is not enough physical RAM to store the open programs
• where is the virtual memory held?

  On the hard disk
• Where are programs transferred to when they are not currently being executed?

  Programs are transferred out to virtual memory from the RAM
• where do programs transferred to when they are being needed?

  back into RAM from virtual memory
• why is secondary storage needed?

  ROM is read only and RAM is volatile
• What is Secondary storage needed for? (4)

  • storage of programs and data when the power is turned off
  • Semi-permanent storage of data that can change
  • Backup of data files
  • Archive of data files
• What are the three common types of storage?

  Optical, Magnetic, Solid-state
• what are the examples of Optical?


  CD -R/RWDVD -R/RW Blu-Ray
• what are the examples of Magnetic?

  Hard disk drive

  magnetic tape
• what are the examples of Solid-State?

  SSD

  Memory sticks

  Flash memory

  cards
• what are the advantages of Optical?


  Thin, lightweight and portable
• what are the disadvantages of Optical?

  low capacity compared to other types

  slow to access data
• what are the advantages of Magnetic?

  high storage capacity

  Quick to access data
• what are the disadvantages of Magnetic?

  • hard disks perform better if they are fragmented
  • has moving parts, which eventually fail
• what are the advantages of Solid-state? (5)

  Very quick to access data,

  no moving parts,

  very reliable

  no noise,

  low power, no need to defragment
• how much is 1 byte?

  8 bits
• how can you convert from bits to a byte?

  divide by 8
• with just two states, electronic components are:


  Easier to manufacture,

  Therefore cheaper,

  More reliable
• what is the formula for size of a text file?

  Bits per character x number of characters
• What is the formula for Calculating sound file sizes?

  sample rate x Duration (s) x bit depth
• what is the formula of calculating image file sizes?


  colour depth x Image height (px) x Image width (px)
• what happens when u shift binary to the left once?

  it times by two
• what happens if you shift binary to the right?

  divide by two
• what is a character set?

  defined list of characters recognised by the computer
• each character is …

  represented by a unique binary number
• what are the well known character sets?

  ASCII - A 7 bit character set with 2^7 characters = 128

  extended ASCII - an 8 bit character set with w^8 characters = 156

  UNICODE - a 24 bit character set with 2^24 characters > 16 million
• what can images be stored in?

  bitmaps or vectors
• how are bitmap pictures constructed?

  from coloured squares called pixels
• what is the purpose of vector pictures?

  store the mathematics to draw coloured shapes.
• Each pixel of a bitmap is stored in...

  Binary
• the number of bits required for each pixel depends...

  on the number of colours required
• the number of colours can be calculated in.

  2 ^n