computing paper 1

• primary storage

  volatile memory

  hold the data programs and instructions currently in use
• Random Access Memory (RAM)


  volatile memory

  used to store information while data is processing

  when a computer is turned off everything stored in RAM is lost.
• read-only memory (ROM)


  non-volatile memory

  contains data that is can be retrieved but can not be changed.

  when a computer is turned off the contents are not lost
• volatile memory

  memory that is lost when the computer is turned off
• non-volatile memory

  Memory that is not lost when the computer is turned off
• virtual memory

  a section of secondary storage that is temporarily used as RAM.

  this is slower than the main memory
• optical storage

  reading and storing data from a disc using a laser.

  for example: CD, DVD.
• magnetic storage

  reading and storing data using magnets.
• solid state storage

  reading and storing data using electricity.

  no moving parts.

  Solid-state storage is likely to replace disk storage in the future.
• hard disk drive (HDD)


  a magnetic storage device that reads, writes, and stores digital data
• digital versatile disk (DVD)


  high capacity disk often used to store videos
• compact disk (CD)


  an optical storage disk often used to store music
• Solid Disk Drive (SDD)


  solid-state storage drive that carries out functions of a traditional HDD
• bit

  the smallest unit of data in a computer

  b

  value = 0 or 1
• nibble

  N

  value = 4 bits
• byte

  B

  value = 8 bits
• kilobyte

  KB

  value = 1000 bytes
• megabyte

  MB

  value = 1000 kilobytes
• gigabyte

  GB

  value = 1000 megabytes
• terabyte

  TB

  value = 1000 gigabytes
• petabyte

  PB

  value = 1000 terabytes
• binary

  number system used by computers which only contains 0 and 1.

  also known as base 2.
• denary

  number system used by people which contains numbers 0 to 9
• positive number

  a number greater than 0
• negative number

  a number below 0
• integer

  a whole number without a decimal or fraction
• overflow error

  Error from attempting to represent a number that is too big.
• hexadecimal

  The hexadecimal number system is base 16, using only digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F.
• binary shift

  moving the bits in a binary number left or right and filling gaps with 0
• most significant bit

  furthest left digit in a string of binary numbers
• Least Significant Bit

  The furthest right digit in a string of binary numbers
• character

  single symbol
• character set

  A list of the characters and the codes used to represent each one

  for example: ASCII and Unicode.
• ASCII

  American Standard Code for Information Interchange

  7 bit character set
• unicode

  A symbol that enables most of the languages in the world to be symbolized with a special character identification.
• pixel

  picture element

  pictures on a computer are divided into a grid each square being 1 pixel
• metadata

  data that describes other data
• colour depth

  the amount of bits available for colours in an image.

  the higher the bit depth the more available colours
• resolution

  the number of pixels an image is divided into.

  the higher the resolution the clearer the image will be.
• sample rate

  the number of samples taken per second